Full opinion text
FAY, Circuit Judge: If “[a]ll the world’s a stage” as Shakespeare wrote, this case demonstrates just how much the dimensions of that stage are shrinking with the advent of the internet, at least in regards to child pornography. We are concerned here with the fruits of a cooperative, multi-national criminal investigation directed at tracking a sprawling international child pornography ring, comprised of as many as 64 known individuals sharing more than 400,000 images and 1,000 videos of child pornography across at least six countries. Ultimately, a joint task force arrested fourteen members of the ring and charged them with offenses relating to child pornography, although we have before us only the appeals of the following seven defendants: Neville McGarity, Daniel Castleman, Gary Lakey, Marvin Lambert, Ronald White, James Freeman, and Warren Mumpower. Faced with a 40-count Superseding Indictment, each defendant was tried and convicted of engaging in a child exploitation enterprise (“CEE”), in violation of 18 U.S.C. § 2252A(g); conspiring to advertise, transport/ship, receive, and possess child pornography, and to obstruct an official proceeding, in violation of 18 U.S.C. §§ 371, 1512(k), 2251(d)(1) and (e), and 2252A(a)(l); receiving child pornography, in violation of 18 U.S.C. § 2252A(a)(2); and obstructing justice, in violation of 18 U.S.C. § 1512(c). Furthermore, all defendants but one, Ronald White, were tried and convicted of advertising the exchange of child pornography, in violation of 18 U.S.C. § 2251(d)(1) and (2); and knowingly transporting and shipping child pornography, in violation of 18 U.S.C. § 2252A(a)(l). Lastly, to compensate for harm to one victim depicted in the child pornography found in the defendants’ possession, the sentencing judge ordered restitution against only one of the defendants, James Freeman, in the amount of $3,263,758. The defendants raise numerous issues on appeal, although many require no discussion. In relevant part, the defendants challenge the constitutionality of the CEE statute; the sufficiency of the Superseding Indictment in regards to Count One and Count Forty; certain errors the district court purportedly made both pretrial and during trial, including the district court’s purported failure to issue a “unanimity” instruction regarding the CEE charge; the sufficiency of the evidence regarding Count Twenty and Count Forty; and an alleged Double Jeopardy violation based on the defendants’ convictions under Counts One and Two. The defendants also challenge their sentences. After review of the record and having had the benefit of oral argument, we vacate Ronald White’s CEE conviction under Count One; vacate the other six defendants’ convictions for conspiracy under Count Two; and vacate all of the defendants’ convictions for statutory obstruction of justice under Count Forty. We also vacate the restitution award against Freeman and remand for further proceedings. In all other regards, we affirm. I. We delineate below both the relevant factual and procedural background. As we must, we consider the factual background in the light most favorable to the Government. See United States v. Glen-Archila, 677 F.2d 809, 812 (11th Cir.1982). A. Discovery and Infiltration of Child Pornography Ring In 2005, an informant notified an Australian constable, Brenden Power, and others of the Queensland Police Service of the existence of a computer ring of child pornography users, which operated exclusively through internet newsgroups. The informant further notified Constable Power of which newsgroups the ring was using, the ring’s encryption method, and the informant’s own nickname within the ring, all of which permitted Constable Power to infiltrate the ring. When he began monitoring the ring, Constable Power discovered the sophisticated nature of the ring’s operations, both in its day-to-day operations and in its recruitment of new members. As to the former, the ring had a hierarchy in place, in which a “core” of leaders — “Yardbird,” “Helen,” “Soft,” and “Tex” — managed the ring, its operations, and its members. To assist the core leadership, the ring also had officers tasked with specific roles, like security and administration. Additionally, the ring had a formal process in place for gaining new members. The most involved leader, Yardbird, would identify potential members based on their online history of posting child pornography. He would subsequently invite those prospective members into the group upon completion of certain tests designed to weed out potential law enforcement infiltrators. For example, most invitees were required to find and post certain electronic files of child pornography, as well as pass a timed child pornography test that provided 48 hours for completion. Once accepted as a member, an invitee was provided with the accoutrements of membership: a PGP key that allowed him to decrypt group postings; several documents pertaining to membership; and an introduction, via online post, to the other group members. Perhaps the most telling proof of the ring’s sophistication, though, came from Constable Power’s investigation of the ring’s communications. The members utilized a maze of rotating newsgroups and parallel newsgroup postings not only to communicate with one another but also to hide their communications from outsiders. As noted above, members of the ring were given separate keys for encryption of newsgroup text posts and for binary uploads containing the images and videos. The encryption keys were subject to change at Yardbird’s discretion. Using those keys, the ring members employed a two-step process in communicating with one another and posting child pornography. First, a member would upload scrambled and encrypted binary files of child pornography to a newsgroup location determined by Yardbird. Each such file was posted under a specified subject line and attributed to the newsgroup nickname associated with the poster. The uploader would then text an encrypted message to another newsgroup in which the ring was active, advising of the upload, its location, and providing pertinent instructions. The recipient members could then download the encrypted message, decrypt and read it, and then follow the instructions contained therein to locate and download the files containing child pornography. The ring also employed other means of avoiding detection, like masking their headings when posting messages or files, or changing the nicknames by which they were known to each other. Ultimately, the international reach of the child pornography ring became apparent to Constable Power. An analysis of unmasked newsgroup posts in conjunction with information obtained from corresponding NSPs enabled Constable Power to determine just how far the ring reached: at its peak it had as many as 64 known members operating in at least six different countries. Therefore, in August 2006, Constable Power came to the United States, where he continued his investigation in conjunction with the Federal Bureau of Investigation’s Innocent Images Unit. The joint investigation continued for over one year. During that time, law enforcement identified 22 members of the child pornography ring, fourteen of whom became people of special interest. In all, the joint investigation detected the upload by ring members of over 400,000 images and more than 1,000 videos from August 31, 2006 through December 15, 2007. Although not all of those images and videos portrayed child pornography, many depicted the sexual abuse of minors in graphic and grotesque detail. Arrest of Members of Child Pornography Ring On or about February 28, 2008, law enforcement agents simultaneously executed search warrants at the defendants’ respective residences. Each search warrant was carried out with alacrity with but one exception: when agents sought to execute the warrant for Daniel Castleman by “knocking and announcing,” he ignored their request for approximately thirty minutes. When they finally gained entrance to Castleman’s home with the assistance of a locksmith, law enforcement agents found him in his living room, running a destructive “wipe” program on his computer. All the defendants except Castleman confessed their involvement with child pornography and with the child pornography sharing ring in question. PGP encryption keys of the type used by Constable Power to access the pertinent newsgroup postings were found in possession of every defendant except Neville McGarity. After being taken into custody and being incarcerated together, six of the seven also admitted to one another their membership in the child pornography ring. B. On February 21, 2008, a Northern District of Florida grand jury indicted twelve defendants on 35 counts of child-related offenses. Almost one month later, the Government filed a Superseding Indictment against fourteen defendants, including the original twelve first named, now alleging 40 counts of criminal offenses related to child pornography. At trial, after being presented with the evidence detailed above, a jury found the defendants guilty of various child pornography-related offenses, as noted above. Each of the defendants was sentenced to life imprisonment for engaging in a CEE, as well as other sentences based upon their specific convictions. This appeal ensued. II. Various standards of review apply to the amalgamated issues raised on this consolidated appeal. We review de novo the constitutionality of a statute. United States v. Spoerke, 568 F.3d 1236, 1244 (11th Cir.2009). A district court’s determination regarding sufficiency of the indictment is a question of law subject to de novo review. See United States v. Pendergraft, 297 F.3d 1198, 1204 (11th Cir. 2002). However, we review a district court’s evidentiary ruling for abuse of discretion. See United States v. Langford, 647 F.3d 1309, 1319 (11th Cir.2011) (citation omitted). “A challenge to a jury instruction presents a question of law subject to de novo review.” United States v. Ndiaye, 434 F.3d 1270, 1280 (11th Cir. 2006). While a district court has “broad discretion in formulating its charge as long as the charge accurately reflects the law and the facts,” Spoerke, 568 F.3d at 1244 (quotation marks omitted), we review for abuse of discretion a district court’s refusal to give a jury instruction. See United States v. Puche, 350 F.3d 1137, 1150 (11th Cir.2003). Whether the evidence is sufficient to sustain a defendant’s conviction is a question of law, which we review de novo. United States v. To, 144 F.3d 737, 743 (11th Cir.1998). The denial of a motion for a mistrial is reviewed for abuse of discretion. United States v. Campa, 529 F.3d 980, 992 (11th Cir.2008). Allegations of prosecutorial misconduct present mixed questions of fact and law that are reviewed de novo. United States v. Noriega, 117 F.3d 1206, 1218 (11th Cir.1997). A district court’s determination of facts that support enhancements under the Sentencing Guidelines are findings of fact subject to the clearly erroneous standard. See United States v. Singh, 291 F.3d 756, 763 (11th Cir.2002). The application of the Sentencing Guidelines to the facts as found by the district court is a question of law that we review de novo. See United States v. Yates, 990 F.2d 1179, 1182 (11th Cir.1993). A district court’s findings of fact for determining a base offense level are subject to the clearly erroneous standard of review. See United States v. Rummer, 89 F.3d 1536, 1544 (11th Cir.1996). Whether a particular guideline applies to a given set of facts is a question of law subject to de novo review. See United States v. Kirkland, 985 F.2d 535, 537 (11th Cir.1993). When a defendant fails to object to a decision by the lower court, the issue is reviewed for plain error. See United States v. Mitchell, 146 F.3d 1338, 1342 (11th Cir.1998). Otherwise, we review the issue de novo. United States v. Ferreira, 275 F.3d 1020, 1024 (11th Cir.2001). Now, we turn to the errors alleged by the defendants. III. All of the defendants challenge the constitutionality of the CEE statute, 18 U.S.C. § 2252A(g), on grounds that the statute is unconstitutionally vague and overbroad. Section 2252A(g) states, in relevant part: A person engages in a child exploitation enterprise ... if the person violates section 1591, section 1201 if the victim is a minor, or chapter 109A (involving a minor victim), 110 (except for sections 2257 and 2257A), or 117 (involving a minor victim), as a part of a series of felony violations constituting three or more separate incidents and involving more than one victim, and commits those offenses in concert with three or more other persons. 18 U.S.C. § 2252A(g)(2) (emphasis added). The defendants contend that the statute is unconstitutionally vague and overbroad because 1) the term “series” is ambiguous and lacks definition; 2) the phrase “three or more separate incidents” is ambiguous as to whether each incident must involve “more than one victim”; and 3) the statute does not specify whether the same three individuals must be involved in each of the predicate felonious incidents. Our precedent in Wayerski forecloses the defendants’ vagueness claims. In Wayerski, four members of the same child pornography-sharing ring in question here were convicted for similar offenses, including engaging in a CEE, in violation of § 2252A(g). Wayerski 624 F.3d at 1346. The Wayerski defendants argued that § 2252A(g) was unconstitutionally vague because the statute did not clarify how a “series of felony violations constituting three or more separate incidents” may occur, id. at 1347-48, and thus did not “provide fair notice of what conduct it proscribes,” id. at 1347. Our Court rejected those contentions, explaining that “[n]othing about § 2252A(g) is vague when applied in the context of the defendants’ actions.” Id. at 1348. Specifically, we noted in Wayerski: Section 2252A(g) defines the predicate offenses that must be committed. The defendants’ activity here satisfied the predicate offenses.... The offenses involved much more than three separate instances and more than one victim, and they occurred in concert with more than three people. Id. Accordingly, we rejected the .defendants’ vagueness challenge because “[o]ne to whose conduct a statute clearly applies may not successfully challenge it [facially] for vagueness.” Id. (quoting Bama Tomato Co. v. U.S. Dep’t of Agric., 112 F.3d 1542, 1547 (11th Cir.1997)) (alteration in original). Identical reasoning applies here. The defendants participated in the same child pornography ring as the Wayerski defendants. And like the Wayerski defendants, the CEE predicate offenses for which the defendants here were convicted all fall within Chapter 110 of Title 18 of the U.S.Code and are thus specifically identified as predicate offenses in the text of § 2252A(g). Moreover, like the Wayerski defendants’ crimes, the defendants’ crimes here “involved much more than three separate instances and more than one victim, and they occurred in concert with more than three people.” Wayerski, 624 F.3d at 1348. As we explained in Wayerski: [T]he defendants participated in a sophisticated group of approximately 45 individuals who advertised and exchanged over the Internet thousands of images and videos of child pornography involving numerous minor children.... During the course of the group’s existence over 400,000 images and videos ... were advertised, transported, and/or received by its members. Id. The defendants’ actions clearly fall within the intended reach of the CEE statute, so their complaints of vagueness are unavailing. Hoffman Estates v. Flipside, Hoffman Estates, Inc., 455 U.S. 489, 495, 102 S.Ct. 1186, 71 L.Ed.2d 362 (1982) (“A [defendant] who engages in some conduct that is clearly proscribed cannot complain of the vagueness of the law as applied to the conduct of others.”). Even assuming, arguendo, that the defendants could facially attack the statute for vagueness, the Wayerski Court rejected this exact claim. In Wayerski, we concluded that § 2252A(g) survived a facial vagueness challenge because it was “clear what the [statute] as a whole prohibits.” Wayerski, 624 F.3d at 1349 (quotation marks and citation omitted). Specifically, we explained that it is clear to a person of ordinary intelligence that § 2252A(g)’s plain language prohibits “the commission of specified child pornography offenses that occur as a series of three or more separate instances, involving two or more victims, and three or more persons acting in concert with the defendant.” Id. at 1349; see United States v. Williams, 553 U.S. 285, 304, 128 S.Ct. 1830, 170 L.Ed.2d 650 (2008) (explaining that a criminal statute is void for vagueness where it “fails to provide a person of ordinary intelligence fair notice of what is prohibited, or is so standardless that it authorizes or encourages seriously discriminatory enforcement”). In this regard, we add to Wayerski’s reasoning the fact that § 2252A(g)’s plain language 1) does not legislate new offenses, but instead relies on established offenses as predicates; and 2) facially limits almost entirely those predicates to offenses involving a minor, with only two of the specified sections not being so delimited: § 1591 and chapter 110. See 18 U.S.C. § 2252A(g)(2). Nonetheless, both § 1591 and chapter 110 also criminalize sexual offenses against children. Section 1591 is entitled “Sex trafficking of children or by force, fraud, or coercion.” 18 U.S.C. § 1591. By its terms, it prohibits anyone from: recruiting], entic[ing], harbor[ing], transporting], providing], obtaining], or maintaining] by any means a person ... [for the purpose of causing] the person to engage in a commercial sex act, or that the person has not attained the age of 18 years and will be caused to engage in a commercial sex act.... Id. § 1591(a)(1)-(2) (emphasis added). Likewise, chapter 110 is entitled “Sexual Exploitation and Other Abuses of Children,” and criminalizes activity relating to the “selling or buying of children,” 18 U.S.C. § 2251A, sexual exploitation of minors, id. § 2252, and other similar offenses. See, e.g., id. §§ 2251, 2260. Thus, the main thrust of both § 1591 and chapter 110 is to prevent harm to minors. Cf. Grayned v. City of Rockford, 408 U.S. 104, 110-11, 92 S.Ct. 2294, 33 L.Ed.2d 222 (1972) (holding antinoise ordinance in question was not -impermissibly vague where “it is clear what the ordinance as a whole prohibits ... ”). We recognize that defendants posit certain hypothetical that they argue demonstrate the vagueness of the CEE statute. So, for instance, § 2252B(a) within chapter 110 prescribes a criminal offense punishable by up to two years in prison for using a misleading domain name with the intent to deceive a person into viewing obscenity. Section 2252B(a) does not require that either the person deceived or the material viewed must involve a minor. Id. Assuming there were three such offenses otherwise meeting the requirements of § 2252A(g), an individual could be prosecuted for engaging in a CEE, regardless of whether any minors were involved in any of the three predicate offenses. To the defendants, this statutory uncertainty “fails to provide a person of ordinary intelligence fair notice of what is prohibited, or is so standardless that it authorizes or encourages seriously discriminatory enforcement.” We disagree. Even if there may be some instances in which certain crimes could be swept into a CEE violation, the only predicates under the CEE statute are nonetheless criminal statutes found elsewhere in the United States Code and there can be no doubt that the CEE statute properly notifies average citizens of what is prohibited, and limits any arbitrary enforcement. Accordingly, the defendants’ purportedly absurd constructions of § 2252A(g) do not require us to invalidate the statute wholesale. Wayerski 624 F.3d at 1349 (“[Speculation about possible vagueness in hypothetical situations not before the Court will not support a facial attack on a statute when it is surely valid in the vast majority of its intended applications.”) (quotation marks and citation omitted). IV. Next, some of the defendants, whom we identify below with specificity, challenge the sufficiency of the Superseding Indictment in regards to two counts: Count One, which charged a violation of the CEE statute under 18 U.S.C. § 2252A(g); and Count Forty, which charged statutory obstruction of justice under 18 U.S.C. § 1512(c). When analyzing such challenges, we “give the indictment a common sense construction, and its validity is to be determined by practical, not technical, considerations.” United States v. Poirier, 321 F.3d 1024, 1029 (11th Cir.2003) (quotation marks and citations omitted). Such a common sense construction is satisfied through consideration of three factors: whether the indictment “1) presents the essential elements of the charged offense, 2) notifies the accused of the charges to be defended against, and 3) enables the accused to rely upon a judgment under the indictment as a bar against double jeopardy for any subsequent prosecution for the same offense.” United States v. Woodruff, 296 F.3d 1041, 1046 (11th Cir.2002) (quotation marks and citations omitted). These factors ensure the provision of constitutional notice and due process. United States v. Fern, 155 F.3d 1318, 1325 (11th Cir.1998); see also United States v. Yonn, 702 F.2d 1341, 1348 (11th Cir.1983) (“To pass constitutional muster, an indictment must be sufficiently specific to inform the defendant of the charge against him and to enable him to plead double jeopardy in any future prosecutions for the same offense.”). Ultimately, “the appropriate test ... is not whether the indictment might have been drafted with more clarity, but whether it conforms to minimal constitutional standards.” United States v. Varkonyi, 645 F.2d 453, 456 (5th Cir.1981). However, “[ejven when an indictment tracks the language of the statute, it must be accompanied with such a statement of the facts and circumstances as will inform the accused of the specific offense, coming under the general description, with which he is charged.” United States v. Schmitz, 634 F.3d 1247, 1261 (11th Cir.2011) (quotation marks and citations omitted). A. After unsuccessfully challenging the sufficiency of the Superseding Indictment as to Count One prior to trial, Castleman, Lakey, Mumpower, Lambert, and McGarity again argue that Count One is insufficient as a matter of law for two reasons: 1) it fails to allege that the defendants acted “in concert with three or more persons”; and 2) it is “hopelessly vague” and “provide[s] no detail” regarding the three predicate offenses under § 2252A(g). Count One of the Superseding Indictment alleges as follows: [0]n or about August 31, 2006, through the date of the return of this superseding indictment, in the Northern District of Florida and elsewhere, the defendants ... did knowingly and willfully engage in a child exploitation enterprise, that is, the advertisement, transportation and shipment of child pornography, as defined in Title 18, United States Code, Section 2256(8)(A), in interstate and foreign commerce by means of a computer, as a series of three or more separate incidents and involving more than one victim, in violation of Title 18, United States Code, Section 2252A(g). We examined this same indictment in Wayerski and concluded that Count One “was plainly sufficient” because it “provided a general description of the facts and predicate offenses” relevant to the CEE charge, specifically, that the defendants advertised, transported, and shipped child pornography. Wayerski, 624 F.3d at 1350. In addition, we found this indictment sufficient as to Count One because it “tracked the language of the statute on which it was based, i.e. § 2252A(g), and provided notice to the defendants of the charges to be defended.” Id.; see United States v. Fern, 155 F.3d 1318, 1325 (11th Cir.1998) (“If an indictment specifically refers to the statute on which the charge was based, the reference to the statutory language adequately informs the defendant of the charge.”). We are bound by our precedent in Wayerski and therefore hold that Count One of the indictment sufficiently alleged a violation of § 2252A(g). Even were we not bound by our decision in Wayerski we would reach the same conclusion. The defendants’ arguments that the indictment did not sufficiently allege a CEE offense are unavailing. In support of their challenge, the defendants cite United States v. Gayle for the contention that a conviction will be overturned where “the indictment upon which it is based does not set forth the essential elements of the offense.” 967 F.2d 483, 485 (11th Cir.1992) (en banc) (citation omitted). But Gayle did not require that an indictment specify each element of an offense with particularity. Rather, Gayle evidences our refusal to require such specificity in certain contexts. In Gayle, two men were arrested for impersonating a federal officer and acting as such, in violation of 18 U.S.C. § 912. After conviction, they appealed, contending that the underlying indictment was insufficient because 1) it “failed to allege that the defendants acted with an ‘intent to defraud’ and consequently did not set forth an essential element of the offense”; and 2) it “fail[ed] to allege that defendants engaged in overt acts beyond the mere impersonation of a federal officer.” Id. at 485, 487. Sitting en banc, we rejected both bases for appeal, holding that the indictment in question sufficiently alleged the relevant elements of a § 912 violation. The linchpin of our holding was that the indictment provided sufficient notice of the allegations against the Gayle defendants. Here, Count One satisfies that same requirement. It alleges knowing and willful involvement in a child exploitation enterprise, which § 2252A(g)(2) defines as a violation of certain sections and chapters of the United States Code, “as a part of a series of felony violations constituting three or more separate incidents and involving more than one victim.” Id. The fact that Count One does not specifically state that the defendants acted “in concert with three or more persons” does not render the indictment insufficient; the indictment’s explicit reference to § 2252A(g) put the defendants on notice as to all of the elements of the CEE offense, including the “in concert” requirement. See Poirier, 321 F.3d at 1029 (“Minor deficiencies that do not prejudice the defendant will not prompt this Court to reverse a conviction.”) (citation omitted). Given that the sufficiency of a charge must be given “a common sense construction,” id., we have no difficulty here finding Count One sufficient as charged. Just as in Gayle, where an “intent to defraud” was presumed from a charge for impersonation of a federal officer, so, too, is acting “in concert with three or more persons” presumed from a charge of engaging in a child exploitation enterprise that explicitly refers to § 2252A(g). As to the defendants’ contention that each predicate offense for a child exploitation enterprise must be pled with specificity in an indictment, we note that we have previously rejected such a claim in a similar context. See United States v. Alvarez-Moreno, 874 F.2d 1402, 1408-11 (11th Cir.1989) (holding predicate offenses for a continuing criminal enterprise prosecution need not be charged in an indictment); United States v. Valencia-Trujillo, 573 F.3d 1171, 1181 (11th Cir.2009) (approving Alvarez-Moreno). In Alvarez-Moreno, we considered whether uncharged criminal offenses could serve as predicate offenses for a prosecution under 21 U.S.C. § 848, which prohibits engaging in a continuing criminal enterprise (“CCE”). There, the question arose in the context of a massive drug conspiracy that involved a Colombian defendant, Carlos Alvarez-Moreno, who was extradited to the United States. At trial, Alvarez-Moreno was convicted of, among other crimes, engaging in a CCE within the meaning of 21 U.S.C. § 848. Id. at 1407. On appeal, Alvarez-Moreno argued that each predicate violation for a CCE offense should have been charged in the indictment. Reviewing relevant, contemporaneous case law, we rejected that contention and held that predicate offenses “need not be charged or even set forth as predicate acts in the indictment.” Id. at 1408 (citation omitted). Instead, “[t]he law only requires evidence that the defendant committed three substantive offenses to provide the predicate for a section 848 violation, regardless of whether such offenses were charged in counts of the indictment....” Id. at 1408-09. We see no reason to vary from this holding for a conviction under 18 U.S.C. § 2252A(g), which the parties (and at least one of our sister circuits) agree should be interpreted similarly to § 848. See United States v. Daniels, 653 F.3d 399, 412 (6th Cir.2011) (“Given the similar language [in the two statutes] we believe that interpretations of § 848 should guide our interpretation of § 2252A(g).”). Accordingly, we hold that, in a CEE indictment, predicate offenses under 18 U.S.C. § 2252A(g) need not be identified with specificity. We therefore reject the defendants’ challenges to the sufficiency of Count One as charged in the Superseding Indictment. B. All of the defendants also challenge the sufficiency of the Superseding Indictment with regard to Count Forty, which charged them with statutory obstruction of justice, in violation of 18 U.S.C. § 1512(c). Prior to trial, they moved for dismissal on the same basis, which was denied. Citing a ruling by the First Circuit in United States v. Murphy, 762 F.2d 1151 (1st Cir.1985), the defendants allege error. They contend that an indictment charging a defendant with statutory obstruction of justice under § 1512(c) must identify which official proceeding was obstructed and otherwise provide sufficient notice to the defendant of the factual predicate for the charge. Given the nature of the charge against the defendants, we must agree. First, we consider the relevant language within the Superseding Indictment. In relevant part, Count Forty alleges as follows: That between on or about October 1, 2005, through the date of the return of this [Superseding [Ijndictment, in the Northern District of Florida and elsewhere, the defendants ... did corruptly obstruct, influence and impede and attempt to corruptly obstruct, influence and impede the due administration of justice in an official proceeding, in violation of Title 18, United States Code, Section 1512(c)(2). By its terms, Count Forty tracks the relevant portions of § 1512(c). Nonetheless, the defendants rely upon Murphy in arguing that some factual notice is required in charging obstruction of justice under the statute. In Murphy, the First Circuit considered whether an indictment must specify which official proceedings were allegedly obstructed by a defendant. There, a man named Richard Watson was a drug informant for local, state, and federal law enforcement agencies. 762 F.2d at 1152. In the course of his role as an informant, Watson introduced many people to an undercover state police officer, as well as purchased cocaine in his informant capacity from a man named Haythem Dawlett. Dawlett was subsequently arrested on federal charges of distributing cocaine. Separately, several other individuals acquainted with Watson — Patrick Murphy, Kevin Deyo, and Steven Quinlivan — were also the subject of another DEA investigation being conducted in the same locale. Id. Those individuals were eventually charged and indicted. They appeared at the Springfield federal courthouse for their arraignment at 10 a.m. on the day in question. Unfortunately, that same day Watson also had a meeting around the same time at the Springfield federal courthouse, where he was supposed to meet with his DEA handler. As he approached the courthouse, Watson spotted Murphy, Deyo, and Quinlivan exiting. Watson, believing they had identified him, turned and headed back in the direction from whence he had come. He testified that Murphy, Deyo, and Quinlivan followed him and threatened bodily harm, presumably because of his role as an informant. Id. at 1158. The Government subsequently filed a one-count indictment against Murphy, Deyo, and Quinlivan for violation of 18 U.S.C. § 1512(c). In its indictment, the Government “parroted the statute” and identified only the date the offense occurred, without identifying which official proceeding the defendants obstructed. The defendants were found guilty. Reversing the conviction, the First Circuit stated as follows: The indictment in the instant case did not identify any proceeding in which defendants were allegedly attempting to influence Watson’s testimony. It is wholly unclear from the indictment whether the grand jury was charging that defendants tried to influence Watson’s testimony in the proceeding against Dawlett, or in the proceeding against them, or in some other proceeding altogether. Crucial to preparation of any defense to a charge under the statute is at least some indication of the identity of the proceeding in which the defendant tried to influence testimony. The indictment at issue here presented no such indication.... Id. at 1154 (emphasis in original). Therefore, finding that “the indictment was defective because it did not adequately apprise the defendants of the charges against them,” the First Circuit vacated the conviction and remanded with instructions to dismiss the underlying indictment. Id. at 1155. In the instant case, the Government concedes that Count Forty does not specify which official proceeding was obstructed. It argues such vagueness is necessary, however, because of the nature of the defendants’ obstruction, which sought to impede “any possible proceeding that might exist.” It further urges that we have upheld similar charges in other indictments. See United States v. Bascaro, 742 F.2d 1335, 1348-49 (11th Cir.1984) (upholding indictment that charged criminal conduct by specifying defendants involved and relevant time span, among other factors), abrogated on other grounds by United States v. Lewis, 492 F.3d 1219 (11th Cir.2007); Ndiaye, 434 F.3d at 1299. Without addressing either Bascaro or Ndiaye, both of which are distinguishable, we note that the Government has not cited any Eleventh Circuit law— nor have we found any upon independent review — that would permit an indictment charging a violation of § 1512(c) under these circumstances. Although Murphy is of course not binding on us, we similarly recognize that an indictment must “sufficiently apprise [ ] the defendants] of what [charges they] must be prepared to meet.” Murphy, 762 F.2d at 1154 (alterations in original) (quoting Russell, 369 U.S. at 763, 82 S.Ct. 1038). Even under a “common sense construction” of an indictment charge, Poirier, 321 F.3d at 1029, the only notice provided here is that the defendants obstructed an unknown official proceeding at some time in some place by some action. This lack of notice does not satisfy Woodruff. Although Count Forty tracks the statutory language of § 1512(c) and therefore satisfies the first consideration, it wholly fails to satisfy either the second or third Woodruff factor. Without some factual predicate anchoring Count Forty’s charge, the Superseding Indictment provides insufficient constitutional notice, both as to what charges must be defended against and as to the possibility of future prosecutions on the same basis. Without some indication of either, the Superseding Indictment cannot be said to “notif[y] the accused of the charges to be defended against.” Woodruff, 296 F.3d at 1046. Although we will not upset a conviction for “minor deficiencies,” Poirier, 321 F.3d at 1029 (quotation marks omitted), these deficiencies cannot be considered minor. As a result, we must vacate all of the defendants’ convictions thereunder. V. Certain defendants also allege error regarding certain rulings both prior to trial and during trial. We consider these alleged errors in turn. A. First, McGarity, Castleman, Lakey, Lambert, Freeman, and Mumpower contend that the district court erred in permitting Warren Weber, a co-defendant, to testify regarding their failure to proclaim their innocence while incarcerated together following their arrests. At trial, the jury heard the following inquiry of Weber by the prosecutor: Prosecutor: Please tell the ladies and gentlemen of the jury which one of these defendants, when charged with a child exploitation enterprise, while locked up, said, “Oh my God, it’s not me I didn’t do any of this----” Which ones denied it? Weber: No one actually ever said that they were innocent. We never discussed that, no. Prosecutor: No one stood up and said, I didn’t do this? Weber: No, sir. Contending that the prosecutor’s inquiry improperly solicited comment on the defendants’ right to remain silent, the defendants objected during and after the Government’s inquiry. The objections were overruled. After the Government rested, the defendants moved for a mistrial on the same basis. The district court denied the motion with the statement that the defense can “tell them in [their] argument.” Now, the defendants again allege error. A prosecutor impermissibly comments on a defendant’s right to remain silent where: “(1) the statement was manifestly intended to be a comment on the defendant’s failure to testify; or (2) the statement was of such a character that a jury would naturally and necessarily take it to be a comment on the failure of the accused to testify.” United States v. Knowles, 66 F.3d 1146, 1162-63 (11th Cir. 1995) (quotation marks and citation omitted) (emphasis in original). “[T]he question is not whether the jury possibly or even probably would review the remark in this manner, but whether the jury necessarily would have done so.” United States v. Swindall, 971 F.2d 1531, 1552 (11th Cir.1992) (quotation marks and citation omitted) (emphasis in original). Although the Government concedes that “eliciting] testimony or argufing] to the jury that a defendant’s decision not to testify is evidence of his guilt” is improper, citing Griffin v. California, 380 U.S. 609, 609-15, 85 S.Ct. 1229, 14 L.Ed.2d 106 (1965), here it argues that the context of the comment made it innocuous and that there was an equally plausible explanation for the remark. United States v. Calderon, 127 F.3d 1314, 1338 (11th Cir.1997). In the Government’s view, Weber’s earlier testimony had touched upon the child pornography ring’s operations and attempts at avoiding law enforcement. On cross-examination, the defense elicited testimony that Weber “only knew other group members by their nicknames and did not personally know other group members.” So, the Government’s argument goes, the testimony in question was not elicited to comment on the defendants’ refusal to testify or decision to remain silent, but rather to demonstrate membership within the child pornography group. Although Weber’s testimony related to the defendants’ failure to proclaim their innocence outside of court rather than commenting on their failure to testify, we nonetheless find the Government’s explanation troubling. Even with the additional context in which the Government places Weber’s testimony, it is unclear how such testimony could have supported an inference of group membership. Instead, the relevant portion of Weber’s testimony was pertinent only to the defendants’ failure to protest their innocence in jail. The inescapable conclusion is therefore that the prosecutor’s line of questioning was intended to elicit exactly the information that it did. However, we need not resolve this issue because any such error did not constitute prejudicial harm. Where error can be remedied by subsequent instruction by the trial court or mitigated by the overwhelming weight of the evidence, it may be considered harmless so long as it does not affect the “substantial rights of the parties.” See United States v. Dulcio, 441 F.3d 1269, 1275 (11th Cir.2006) (quoting United States v. Cameron, 907 F.2d 1051, 1059 (11th Cir.1990) (holding that “error in the admission or exclusion of evidence is harmless if it does not affect the substantial rights of the parties”)). This principle applies here. Any error in admitting Weber’s testimony was overridden by both the overwhelming evidence of the defendants’ guilt, and by the court’s subsequent jury instructions. See United States v. Turner, 871 F.2d 1574, 1582 (11th Cir.1989) (detailing factors to be considered in assessing existence of harmless error). As to the former, the Government produced overwhelming evidence of the defendants’ guilt. Numerous witnesses, including Constable Power and various FBI special agents, testified regarding the types of child pornography shared amongst the defendants over the course of the investigation. Most newsgroup posts — both text and binary — were saved by Constable Power to his hard drive, processed by the FBI, and admitted into evidence at trial. The binary posts admitted into evidence contained thousands of images and videos of abhorrent child pornography, posted on request and cavalierly bandied back and forth between the defendants. Similarly, the text posts demonstrated not only knowledge of the nature of the videos and images being shared, but also an utter disregard for the health or welfare of the children being abused and exploited in the pornography being shared. The Government also introduced supporting records, which traced the ownership and control of the NSP accounts used to access the newsgroups utilized by the far-flung child pornography ring. Payment records, credit card invoices, IP addresses, proof of service by the respective internet providers, computer drives, and other hard evidence found at each defendant’s residence all confirmed the defendants’ involvement. Moreover, PGP encryption keys, nickname spreadsheets detailing the various nicknames used by each group member in each newsgroup, and the like literally littered the defendants’ homes. On top of that evidence, all but one defendant confessed to his involvement, informing law enforcement of his respective screennames, the types of pornography in which he traded, and the lengths to which the ring members went to avoid detection. Given such voluminous evidence of guilt and combined with the defendants’ own admissions, the Government’s solicitation of Weber’s testimony must be considered harmless. See, e.g., United States v. Cano, 289 F.3d 1354, 1360-64 (11th Cir.2002) (concluding admission of testimony was harmless error because of other overwhelming evidence of guilt). The district judge’s instructions also militate against finding prejudicial error here. He instructed the jurors to consider the totality of the evidence and, if appropriate, to base their findings of the defendants’ guilt upon “proof of such a convincing character that [the jurors] would be willing to rely and act upon it without hesitation in the most important of your affairs.” More pointedly, he emphasized that the testimony of such witnesses as Weber “must be considered with more caution than the testimony of other witnesses.” The district judge’s instruction regarding the caution with which Weber’s testimony must be treated was further strengthened by another warning that any testimony regarding “statements or admissions to someone after being arrested or detained ... [must be considered] with caution and great care.” In addition, the district court expressly instructed the jury that the defendants’ failure to testify could not be used as evidence of guilt. The cumulative effect of these instructions was to limit the impact of testimony such as Weber’s upon the jury’s findings. Accordingly, both on the basis of the overwhelming evidence of the defendants’ guilt and the district court’s jury instructions, any alleged error resulting from the prosecutor’s improper solicitation of testimony was harmless. B. Next, McGarity contends that a typed statement he had made prior to trial was improperly admitted at trial. He had provided the typed statement on or about February 28, 2008, when law enforcement agents arrived at his house with a search warrant. In the statement, McGarity detailed his sexual attraction to children between ages two and five, his failures in resisting those attractions, and his prior fondling, touching, and molestation of his two-year-old daughter some nine years earlier (although he also said that he had “never once ... penetrate[d] her, hurt her or demeanfed] her in any way whatsoever....”). When the Government sought to admit his statement and publish it to the jury, McGarity objected that it was inadmissible pursuant to Federal Rules of Evidence 403 and 404(b) because of the “overwhelming evidence of guilt.” The district court overruled that objection, but nonetheless issued a limiting jury instruction. Now, McGarity alleges error in the admission of his statement. McGarity relies upon a former Fifth Circuit case, United States v. San Martin, 505 F.2d 918 (5th Cir.1974), which he contends set the threshold requirements for admission of prior criminal acts. In San Martin, the Fifth Circuit considered whether evidence of prior criminal acts for resisting or opposing a police officer could be used at trial for a similar crime. In disallowing the evidence at issue, the court noted several prerequisites to the admission of any such evidence: 1. Proof of the prior similar offenses must be “plain, clear and convincing”; 2. The offenses must not be too remote in time to the alleged crime; 3. The element of the prior crime for which there is a recognized exception to the general rule, such as intent, must be a material issue in the instant case; [and] 4. There must be a substantial need for the probative value of the evidence provided for by the prior crimes. Id. at 921-22. Here, McGarity argues that neither the third nor fourth prongs of the San Martin test were met. While we recognize the factors laid out by the San Martin court, we find that those factors are now largely subsumed within a trial court’s inquiry under the Federal Rules of Evidence. So, for instance, the Rules generally prohibit the admission of propensity evidence. See Fed.R.Evid. 404(b) (“Evidence of other crimes, wrongs, or acts is not admissible to prove the character of a person in order to show action in conformity therewith.”). Nonetheless, they provide a specific exception for “child molestation” cases. Specifically, Federal Rule of Evidence 414(a) provides: In a criminal case in which the defendant is accused of an offense of child molestation, evidence of the defendant’s commission of another offense or offenses of child molestation is admissible, and may be considered for its bearing on any matter to which it is relevant. The phrase “offense of child molestation” includes “any conduct proscribed by chapter 110 of title 118, United States Code.” Fed.R.Evid. 414(d)(2). Advertising, transporting, and receiving visual depictions of child pornography, in violation of 18 U.S.C. § 2252(a)(4)(B), and receiving visual depictions of child pornography, in violation of 18 U.S.C. §§ 2251(d), 2252A(a)(l) and 2252A(a)(2), are offenses within chapter 110 of title 18. It thus follows that McGarity’s written confession could be properly admitted against him, so long as its admission satisfied other relevant Rules of Evidence. Our primary concern is therefore whether the admission of McGarity’s written confession was proper under Rule 403. We find that it was. Rule 403 provides that “evidence may be excluded if its probative value is substantially outweighed by the danger of unfair prejudice, confusion of the issues, or misleading the jury, or by considerations of undue delay, waste of time, or needless presentation of cumulative evidence.” Fed.R.Evid. 403. To make such a determination, the context of both the evidence and its admission must be considered. United States v. Lopez, 649 F.3d 1222, 1247-48 (11th Cir.2011) (considering context of admission of evidence under Rule 403 inquiry) A review of the factual and procedural context at trial supports the district court’s decision to admit the written statement, as it provided necessary context to the plethora of evidence introduced against McGarity by the Government. The weight of the evidence introduced against McGarity was substantial. For example, the Government presented the jury evidence of McGarity’s screennames, which he used in posting over 800 messages to the pornography ring, as well his NSP identification, his NSP address, and his payment information for those services. Nonetheless, the nature of McGarity’s crime was intended to avoid detection. It took a lengthy and expensive investigation to understand and to trace the type of activity in which McGarity participated. In such a context, we will not find improper the district court’s admission of McGarity’s written confession, where it could have been used not only to make the Government’s case “believable but also understandable.” Lopez, 649 F.3d at 1248. The fact that the district court considered McGarity’s objections contemporaneously during a sidebar — as well as offering a limiting instruction to the jury — only further supports the court’s decision to admit the written statement. As such, the admission of McGarity’s written statement was not error. C. Defendants McGarity, Lakey, Lambert, White, and Mumpower also contend that a mistrial was warranted because of three allegedly improper prosecutorial arguments. We find that only one of the defendants’ challenges necessitates discussion. During its closing argument, the Government argued as follows: Prosecutor: The market for it [child pornography] is sitting directly behind me. These children would not be raped— Defense: Objection, improper argument. Court: Sustained. Prosecutor: The victims in these videos and images, they’re the children. They’re our daughters and granddaughters, neighbors, friends. Sometimes at night when I’m sitting in my house and everyone is asleep and even the puppy is down, it’s awfully quiet, I can’t fall asleep, sometimes you can hear the crying. Defense: Objection, improper argument. Court: Sustained. Prosecutor: You saw it on the video. I don’t have to state it. I can’t protect all the kids. At some point when the ■ evidence is there, which is overwhelmingly here, there needs to be a verdict as to the Defendants who amass all this stuff, who work together to get all this stuff, who write over and over again how much they enjoy all this stuff, how these kids being penetrated arouse them and they like it. The evidence is overwhelming. It’s not complex. It’s good old fashioned police work. Please return a verdict of guilt on all counts. Notwithstanding that their objections were sustained, the defendants contend a curative instruction was required but not issued. As noted above in Section V(A), supra, when we review an issue of prosecutorial misconduct, we must determine (1) whether the challenged comments were improper and (2) if so, whether they prejudiced the defendant’s substantial rights. United, States v. Paul, 175 F.3d 906, 909 (11th Cir.1999). “A defendant’s substantial rights are prejudicially affected when a reasonable probability arises that, but for the remarks, the outcome of the trial would have been different.” United States v. Eckhardt, 466 F.3d 938, 947 (11th Cir.2006); see also United States v. Bailey, 123 F.3d 1381, 1400 n. 25 (11th Cir.1997) (“For a prosecutor’s closing argument to violate due process, the remarks must be improper and a reasonable probability must exist that, but for the offending remarks, the defendant would not have been convicted.”) (quotation marks and citation omitted).We find that the first prong of our inquiry is satisfied, but that the second is not. As to the first prong, by telling the jury that the victims of the child pornography are “our daughters and granddaughters, neighbors, friends,” the prosecutor here crossed the line between “demarcating permissible oratorical flourish from impermissible comment.” United States v. Kopituk, 690 F.2d 1289, 1342 (11th Cir.1982). Here there is no doubt of the impropriety of the emotional appeal to the jurors to recognize that the victims depicted in the thousands of images and videos were the jurors’ own “daughters and granddaughters” and that “you can hear the crying.” Nonetheless, the improper argument did not so prejudicially affect the defendants’ rights that a different outcome might have been achieved in its absence. In determining the level of prejudice stemming from a prosecutor’s comment, we examine that comment in the context of the entire trial and in light of any curative instruction. Wilson, 149 F.3d at 1301; see also United States v. Hernandez, 145 F.3d 1433, 1438 (11th Cir.1998). As listed above, the district court sustained objections to the offending prosecutorial statements and thrice provided curative instructions admonishing that the jury “must consider only the evidence that has been admitted in the case,” “anything the attorneys said is not evidence in the case,” and “[w]hat the attorneys say is not binding upon you.” See Bailey, 123 F.3d at 1402 (“[A]ny possible prejudice to Bailey resulting from the prosecutor’s closing argument was cured by instructions from the district judge that the lawyers’ arguments were not evidence and that the jury was to decide the case solely on the evidence presented at trial.”). As we have already noted, supra, the weight of the evidence against the defendants was overwhelming. We need not delineate that evidence again. Instead, we only reaffirm that the weight of the evidence here was so overwhelming that the impropriety of the prosecutor’s argument could have had no bearing on the jury’s determination. See Eckhardt, 466 F.Sd at 947 (finding that prosecutorial statements, even if improper, were not so cumulative as to demonstrate substantial error, and also that weight of evidence would have led to conviction even in the absence of those statements). At a minimum, the defendants have not carried their burden to show a reasonable probability that but for the remarks, the outcome of the trial would have been different. Therefore, we deny the defendants’ challenge on the basis of improper prosecutorial argument. D. The defendants also challenge the district court’s failure to issue a “unanimity” instruction in regard to the CEE charge of the Superseding Indictment. All seven defendants were charged in Count One with violating the CEE statute. In relevant part, § 2252A(g) prohibits engaging in a “child exploitation enterprise ... as a part of a señes of felony violations constituting three or more separate incidents .... ” Id. (emphasis added). The jury subsequently convicted each defendant. Now, the defendants contend both that 1) the district court was required to instruct the jury that any determination of predicate acts under § 2252A(g) had to be unanimous; and 2) that failure to administer such an instruction constitutes substantial and prejudicial harm. 1. In its response and at oral argument, the Government concedes that the district court was required to give a unanimity instruction. Notwithstanding this concession, we nonetheless analyze this requirement below because of its relevance to subsequent discussion. The need for a unanimity instruction arises out of § 2252A(g)’s “series” requirement. During trial, some of the defendants requested a unanimity instruction as to Count One of the Superseding Indictment. For example, Freeman’s proposed jury instructions requested that each juror be instructed to “unanimously agree about which three [or more predicate] violations the Defendant committed.” Id. Similarly, he later proposed the following, additional instruction: Regarding the substantive counts charging a defendant with the advertisement of child pornography, the transportation and shipment of child pornography, and the receipt of child pornography, if there was evidence presented showing more than one incident that could constitute a violation of the respective statute, you must unanimously agree on at least one specific incident that would constitute a violation of the statute in order to find the defendant guilty. (emphasis added). The Government’s own proposed jury instruction as to Count One contained no such requirement for unanimity. On the recommendation of the Government, the defendants’ proposals were rejected and the district court’s jury instructions made no reference to unanimity. The defendants now appeal that jury instruction, claiming that “it [is not only] impossible to conclude beyond a reasonable doubt that the jury would have unanimously found that [they] committed three or more specific violations, [but] it is also impossible to conclude beyond a reasonable doubt that the jury determined [they] acted in concert with the same three persons.” The Supreme Court has considered this same issue in a similar context. In Richardson v. United States, 526 U.S. 813, 119 S.Ct. 1707, 143 L.Ed.2d 985 (1999), the Court was faced with a district court’s refusal to issue a unanimity instruction in the context of the CCE statute, 21 U.S.C. § 848, which prohibits “engaging] in a continuing criminal enterprise.” Id. at 815, 119 S.Ct. 1707. Section 848 states: [A] person is engaged in a continuing criminal enterprise if— (1) he violates any provision of [the federal drug laws, ie.,] this subchapter or subchapter II of this chapter the punishment for which is a felony, and (2) such violation is a part of a continuing series of violations of [the federal drug laws, i.e.] this subchapter or sub-chapter II of this chapter— (A) which are undertaken by such person in concert with five or more other persons with respect to whom such person occupies a position of organizer [or supervisor or manager] and (B) from which such person obtains substantial income or resources. § 848(c). In Richardson, the United States prosecuted a man named Eddie Richardson for his involvement in organized crime and related criminal activity. At trial, the Government presented evidence that Richardson had organized a Chicago street gang that distributed heroin, crack cocaine, and powder cocaine for a number of years. Also, the Government’s evidence showed that Richardson had run the gang. After the close of evidence, Richardson requested the district court instruct the jury that they must “unanimously agree on which three acts constituted [the] series of violations” within the meaning of § 848(c). Richardson, 526 U.S. at 816, 119 S.Ct. 1707 (alteration in original). The district court denied that request, instead instructing the jury only that “they must unanimously agree that the defendant committed at least three federal narcotic offenses,” while adding that they did not “have to agree as to the particular three or more federal narcotics offenses committed by the defendant.” Id. The Seventh Circuit upheld the district court’s jury instruction. United States v. Richardson, 130 F.3d 765 (7th Cir.1997). On review, the relevant issue before the Richardson Court was whether each violation constituted an element of the crime for engaging in a CCE, or instead whether predicate offenses for a CCE violation were simply a “means” of violating the statute. Noting that the statutory language was fairly ambiguous as to intent, nonetheless the Supreme Court found that the plain meaning of “violation” seemed to imply a requirement for individual proof. Id. at 818-19, 119 S.Ct. 1707. Similarly, the breadth of any activity that could be defined as a “violation” counseled in favor of finding that Congress had intended each violation to be proven individually. Id. at 819, 119 S.Ct. 1707. As a fina