Full opinion text
TORRUELLA, Chief Judge. After a nine-day trial, Appellant Gerard DiSanto (“Appellant”) was convicted for attempted arson in violation of 18 U.S.C. § 844(i), the federal arson statute, which makes it a federal crime to destroy by means of fire property used in or affecting interstate or foreign commerce; and for conspiracy to commit arson in violation of 18 U.S.C. § 371. Appellant appeals his conviction as well as his sentence on a number of grounds. For the following reasons, we affirm the district court’s judgment and sentence in all respects. FACTUAL AND PROCEDURAL BACKGROUND Presenting the facts in the light most hospitable to the jury’s verdict, see United States v. Staula, 80 F.3d 596, 599 (1st Cir. 1996); United States v. Ortiz, 966 F.2d 707, 711 (1st Cir.1992), cert. denied, 506 U.S. 1063, 113 S.Ct. 1005, 122 L.Ed.2d 154 (1993), the evidence presented during the nine-day trial tended to show the following. The Galleria II was a family-style restaurant and pub serving Italian food and pizza, located in Westport, Massachusetts (the “restaurant”), which was owned by three partners: Appellant, Robert Ashness (“Ashness”) and Dr. Louis Aguiar (“Dr. Aguiar”). The restaurant was located in a building which Appellant and Ashness leased from Dr. Aguiar and Fernando Lopes (“Lopes”). The lease agreement provided, among other things, for a monthly rent of $3,600 and an option for the restaurant owners to purchase Lopes’ share in the property. The restaurant received natural gas and food supplies that moved through interstate commerce. Although very successful during the summer months of 1991, its first year of operation, the Galleria II’s business proved to be seasonal and business slowed considerably after the summer. In addition to the slow business, there were significant problems with the building’s water and septic systems and the relationship between Appellant and Dr. Aguiar deteriorated over who was responsible to pay for the required improvements: the restaurant, as tenant, or Dr. Aguiar and Lopes, as landlords. Among the Galleria II’s employees, Randy Schaller (“Sehaller”) served as chef and as kitchen manager; and Shelley McKenna (“McKenna”) served as the bar manager and hostess and was also responsible for the cash and bookkeeping. Both Schaller and McKenna had longstanding business relationships with Appellant and considered him a friend. Beginning in the fall of 1991, Appellant began discussing with Schaller the need for renovating the restaurant. In addition to correcting the water and septic systems, Appellant proposed that an outside roof-top deck be installed for the purpose of increasing liquor sales during the peak summer season. Appellant told Schaller that he wanted to finance the renovations by burning the top of the restaurant above the second floor as the insurance proceeds from the fire would provide funds for the renovations. As part of his plan, Appellant increased the Galleria II’s existing insurance coverage (building, contents, and premises liability) by purchasing $90,000 of business interruption insurance, which became effective December 3, 1991, two months before the arson attempts. The proceeds from the business interruption coverage could have been used for any purpose, including for the repair of the water and septic systems. On or about February 19, 1992, after unsuccessfully attempting to hire someone else to bum the top of the restaurant, Appellant attempted to set a fire himself by igniting a stack of papers in the attic of the restaurant. The fire burned out, however, before it could fully ignite the exposed wood frame. Both Schaller and McKenna, who had been drawn to the attic because of the open attic door, discovered Appellant standing over the burning stack of papers and refused to get involved. During the days following his first failed attempt, Appellant asked Schaller if he would help by pouring gasoline on the attic rafters as part of a plan whereby Appellant would return later to ignite the gasoline. After repeatedly declining to get involved, Schaller finally agreed to assist Appellant. Shortly after noon on February 23, 1992, Schaller poured gasoline, as Appellant had requested, onto the exposed attic rafters and insulation and informed Appellant that he had done so. About mid-afternoon, Appellant and Schaller left the restaurant. At approximately 4:00 p.m. that same afternoon, the Westport Fire Department responded to a complaint from the restaurant that there was' a strong odor of gas, which both patrons and employees at the restaurant had detected. After evacuating the building, the firefighters discovered the gasoline-soaked boards and insulation as well as evidence of charring on the attic floor and ceiling. According to the fire department, the charring was unrelated to the much larger area of the attic that was saturated with gasoline, representing a separate, previous attempt to start afire. A few days later, Schaller admitted to the police that he had poured the gasoline. Although Appellant told law enforcement officials that he would fire Schaller when they informed him of Schaller’s confession, Appellant never fired Sehaller, and Schaller worked at the restaurant until it closed. On December 6, 1993, Schaller entered a plea of guilty to the federal indictment charging him with the second attempted arson. Pursuant to his plea agreement, he agreed to cooperate with law enforcement officials. As part of that cooperation, Schaller engaged in four conversations — three in person and one by telephone — with Appellant that were recorded by law enforcement agents. In July 1994, a two count indictment was returned by the federal grand jury charging Appellant with attempted arson of a building affecting interstate commerce under 18 U.S.C. § 844(i) and conspiracy to commit arson under 18 U.S.C. § 371. Prior to trial, Appellant filed a motion in limine to exclude from evidence the four recorded conversations between Appellant and Schaller, which included incriminating statements made by Appellant. After a hearing, the court denied the motion and admitted the tapes after certain portions were excised. During a nine-day trial on the merits, in which nine witnesses testified for the prosecution (including Schaller, pursuant to his plea agreement), the prosecution presented its theory that Appellant attempted to bum the restaurant in order to recover insurance proceeds to finance renovations and improvements of the restaurant. The defense called three witnesses, including McKenna. Among other matters, the witnesses testified that Schaller’s reputation for truthfulness was “zero;” that the business interruption insurance was purchased as a result of significant storms which had caused the Galleria II to close; that, after leaving with Schaller during the afternoon of February 22, Appellant had no intention of returning to the restaurant; and that Appellant was with McKenna during the evening of February 22, planning their next day’s business trip. During the trial, Appellant moved for a mistrial, which was denied, on the grounds that improper testimony regarding his ownership of a “gay night club” was prejudicial. Both at the close of the government’s casein-chief and at the close of all the evidence, Appellant moved for judgment of acquittal on the ground that the evidence was insufficient to establish that the Galleria II was a building affecting interstate commerce. The district court denied both motions. Based on the foregoing and other evidence, the jury convicted Appellant on February 10, 1995, on both counts of attempted arson and conspiracy to commit arson. Appellant subsequently moved for a new trial which the district court denied. On May 25, 1995, the district court sentenced Appellant to a term of seventy-eight (78) months’ imprisonment, imposed a fine of $12,500, restitution to the Westport Police Department in the amount of $886, and ordered supervised release for three (3) years. Appellant appeals both his conviction and his sentence. We have jurisdiction pursuant to Bule 4(b). of Federal Buies of Appellate Procedure. DISCUSSION I. Appellant’s Motions for Judgment of Acquittal Appellant claims reversible error in the denial of his motions for judgment of acquittal. See Fed.B.Crim.P. 29. Below, Appellant based his motions for acquittal on sufficiency of the evidence grounds, which included the argument that there was insufficient evidence to prove the requisite nexus to interstate commerce under the federal arson statute. On appeal, he raises new arguments based on the Supreme Court’s decision in United States v. López, — U.S. -, 115 S.Ct. 1624, 131 L.Ed.2d 626 (1995), which struck down the Gun Free School Zone Act, 18 U.S.C. § 922(q), as exceeding Congress’ authority under the Commerce Clause to regulate interstate commerce. Appellant now argues that, in light of López, the federal arson statute is unconstitutional and that, accordingly, the district court lacked subject matter jurisdiction. In the alternative, Appellant argues that under López there is insufficient evidence to prove that the Galleria II was a building that “substantially affected” interstate commerce. Specifically, Appellant now claims that this is a simple state arson case which Congress has no power under the Commerce Clause to federalize and thereby undercut Massachusetts’ power to prosecute Appellant under its own arson statute, Mass.Gen.Laws Ann. ch. 266, § 1. In support of this argument, Appellant insists that López effectively overruled the Supreme Court’s earlier decision in Russell v. United States, 471 U.S. 858, 859, 105 S.Ct. 2455, 2456, 85 L.Ed.2d 829 (1985), which concluded that the federal arson statute expresses Congressional intent to exercise its full power under the Commerce Clause. Id. (holding that rental property was property used in an activity affecting interstate commerce within the meaning of the federal arson statute). Consequently, Appellant challenges the “continuing viability” of United States v. Medeiros, 897 F.2d 13 (1st Cir.1990), in which we held that after Russell rental property is per se “unquestionably sufficiently connected to interstate commerce to confer jurisdiction” and satisfy the jurisdictional element of the federal arson statute. Id. at 16-17. Appellant, thus, urges us to reexamine our holding in Medeiros in light of López’ “substantially affect” nexus requirement between the illegal activity and interstate commerce, and reverse his convictions on the grounds that the evidence does not prove that the attempted arson of the Galleria II “substantially affects” interstate commerce. A. The Constitutionality of Section 844(i) 1. Standard of Review Although Appellant failed to raise his López-based challenge below, a claim that a statute is unconstitutional or that the court lacked jurisdiction may be raised for the first time on appeal. United States v. Seuss, 474 F.2d 385, 387 n. 2 (1st Cir.), cert. denied., 412 U.S. 928, 93 S.Ct. 2751, 37 L.Ed.2d 155 (1973); see also, Fed.R.Crim.P. 12(b)(2) (lack of jurisdiction may be noticed by the court at any time). We review a determination of the constitutionality of a federal statute de novo. See United States v. Díaz-Martínez, 71 F.3d 946, 953 (1st Cir. 1995) (applying, without explicitly stating so, de novo review to López-based constitutional challenge not raised during pre-Lopez proceedings); United States v. Sherlin, 67 F.3d 1208, 1213-14 (6th Cir.1995) (applying de novo review to López-based constitutional challenge to the federal arson statute), cert. denied, — U.S. -, 116 S.Ct. 795, 133 L.Ed.2d 744 (1996); United States v. Aguilar-Aranceta, 957 F.2d 18, 21 (1st Cir.1992) (reviewing de novo questions of constitutional law). But see United States v. Spires, 79 F.3d 464, 465 (5th Cir.1996) (reviewing only for plain error López-based constitutional challenge not raised below during pre-López proceedings); United States v. Dupaquier, 74 F.3d 615, 619 (5th Cir.1996) (same); Daigle v. Maine Medical Center, Inc., 14 F.3d 684, 687-88 (1st Cir.1994) (“The raise-or-waive rule applies with full force to constitutional challenges.”). Regardless of what standard of review we apply, the result is the same since even under the more favorable de novo standard, we reject Appellant’s constitutional and jurisdictional challenges, finding that López in no way provides grounds for reversal in this case. 2. Discussion As with the federal arson statute at issue here, Congress has often invoked its authority under the Commerce Clause to federalize criminal activity. Appellant points to López and its invalidation of the Gun Free School Zone Act as evidence that the Supreme Court’s present position is to restrictively interpret the Commerce Clause when it is used as a foundation for a criminal statute. See López, — U.S. at-n. 3, 115 S.Ct. at 1631 n. 3 (“Under our federal system, the ‘States possess primary authority for defining and enforcing the federal law.’ ” (quoting Brecht v. Abrahamson, 507 U.S. 619, 635, 113 S.Ct. 1710, 1720, 123 L.Ed.2d 353 (1993))). The López Court recognized three categories of activity which Congress may regulate under the Commerce Clause: (i) “the use of the channels of interstate commerce”; (ii) “the instrumentalities of interstate commerce, or persons or things in interstate commerce, even though the threat may come only from intrastate activities”; and (in) “those activities that substantially affect interstate commerce.” López, — U.S. at---, 115 S.Ct. at 1629-30. After López, the Court explained in United, States v. Robertson, — U.S. -, 115 S.Ct. 1732, 131 L.Ed.2d 714 (1995) (per curiam), that these three bases of congressional authority are analytically distinct, reaffirming the distinction between activities engaged in interstate commerce and purely intrastate activities having a substantial effect on interstate commerce. See Robertson, — U.S. at -, 115 S.Ct. at 1733. The Court stated that the “ ‘affecting commerce’ test was developed in our jurisprudence to define the extent of Congress’ power over purely intra state commercial activities that nonetheless have substantial inter state effects.” Id. at-, 115 S.Ct. at 1733 (emphasis in original) (concluding that transporting equipment and workers from out of state fell within 18 U.S.C. § 1962(a)’s alternative criterion without regard to the “affecting commerce” test). We consider the federal arson statute and the Court’s pre-López holding in Russell in light of this framework, concluding that López does not invalidate 18 U.S.C. § 844(i). First, by its plain language, Section 844(i) clearly falls under both the second and third López categories in that it protects property that is either “used in interstate or foreign commerce or in any activity affecting interstate or foreign commerce.” 18 U.S.C. § 844(i) (emphasis added). Second, the federal arson statute contains the requisite “jurisdictional element” and thus is readily distinguishable from the provision invalidated in López. As we recently noted in Diaz-Martinez, the Supreme Court in López “found significant that the statute in that case, 18 U.S.C. § 922(q) [the federal firearms possession statute], ‘contain[ed] no jurisdictional element which would ensure, through case-by-ease inquiry, that the firearm possession in question affects interstate commerce.’ ” Diaz-Martinez, 71 F.3d at 953 (quoting López, — U.S. at-, 115 S.Ct. at 1631). We held that, unlike López, the jurisdictional element was present in 18 U.S.C. § 922(k) because it contains a specific requirement that the firearm with the obliterated serial number have been “shipped or transported in interstate or foreign commerce.” 18 U.S.C. § 922(k); Diaz-Martinez, 71 F.3d at 953 (holding that “[w]hatever the reach of López, it does not invalidate 18 U.S.C. § 922(k)”). Here, too, the federal arson statute contains the requisite jurisdictional element which similarly ensures that, case-by-case, the property damaged by the arson must have been “used in interstate ... commerce or in an activity affecting interstate ... commerce.” 18 U.S.C. § 844(i). Third, while the federal arson statute is similar to that struck down in López in that it does not regulate commercial or economic activity, see United States v. Pappadopoulos, 64 F.3d 522, 526-27 (9th Cir.1995), it does regulate the damage or destruction of business property that satisfies the requisite interstate nexus, see Russell, 471 U.S. at 860-62, 105 S.Ct. at 2457 (“Congress at least intended to protect all business property”); United States v. Flaherty, 76 F.3d 967, 974 (8th Cir.1996). Particularly in the absence of any mention of Russell in the majority opinion of López, we can find no reason to conclude that López invalidates Russell’s analysis of Section 844(i)’s purpose and legislative history or its conclusion that the federal arson statute constitutionally regulates arson of business property that satisfies the requisite jurisdictional element. Russell, 471 U.S. at 860-62, 105 S.Ct. at 2456-58. After all, whatever López ’ reach, it certainly did not purport to overrule cases upholding application of the Commerce Clause power to wholly intrastate activities satisfying the requisite nexus to interstate commerce. See United States v. Genao, 79 F.3d 1333, 1336 (2d Cir. 1996). Furthermore, we reject Appellant’s argument that Section 844(i) is unconstitutional because it improperly intrudes into Massachusetts’ primary authority for defining and enforcing the criminal law. By virtue of the fact that the federal arson statute is a criminal law it indeed intrudes upon states’ traditional dominion over the criminal law. López, — U.S. at-n. 3, 115 S.Ct. at 1631 n. 3 (“Under our federal system, the ‘States possess primary authority for defining and enforcing the criminal law.’ ” (quoting Abrahamson, 507 U.S. at 685, 113 S.Ct. at 1720)). However, “not every federal foray into criminal law is invalid.” United States v. Bishop, 66 F.3d 569, 584 (3d Cir.1995) (rejecting López-based challenge to the constitutionality of the federal carjacking statute, 18 U.S.C. § 2119). Where, as here, the criminal statute satisfies the constitutional limits of the Commerce Clause, it withstands the challenge that it interferes with the states’ ability to define and enforce the criminal law. See Russell, 471 U.S. at 860-62, 105 S.Ct. at 2456-58. Finally, we note that we join our fellow circuits in arriving at the conclusion that 18 U.S.C. § 844(i) passes constitutional muster under López. See, e.g., Flaherty, 76 F.3d at 974; United States v. Denalli, 73 F.3d 328, 329 (11th Cir.1996); Sherlin, 67 F.3d at 1213-14; Pappadopoulos, 64 F.3d at 526. Because we find no basis to question the presumed validity of 18 U.S.C. § 844(i), we conclude that the district court properly had subject-matter jurisdiction conferred by virtue of the fact that Appellant was charged with an “offense against the United States.” 18 U.S.C. § 3231. See United States v. Ryan, 41 F.3d 361, 363-64 (8th Cir.1994) (noting that “if [the jurisdictional] element is not satisfied, then [defendant] is not guilty; but the court is not by the failure of proof on that element deprived of judicial jurisdiction.”). B. Sufficiency of the Evidence With respect to Appellant’s claim that there was insufficient evidence to sustain his convictions, Appellant “faces an uphill climb,” United States v. Valle, 72 F.3d 210, 216 (1st Cir.1995). “If the evidence presented, taken in the light most agreeable to the govemment, is adequate to permit a rational jury to find each essential element of the offense of conviction beyond a reasonable doubt, then [Appellant’s] claim fails.” Id. (citations omitted). As the district court’s disposition of a motion for judgment of acquittal is subject to de novo review, we, “like the trial court, must ‘scrutinize the evidence in the light most compatible with the verdict, resolve all credibility disputes in the verdict’s favor, and then reach a judgment whether a rational jury could find guilt beyond a reasonable doubt.’ ” Id. (quoting United States v. Taylor, 54 F.3d 967, 974 (1st Cir.1995)). After thoroughly reviewing the record and applying these straightforward rules, we are convinced that a rational jury could have found beyond a reasonable doubt that the government had successfully proved each of the elements — including, as we discuss more thoroughly below, the requisite nexus to interstate commerce — of both Appellant’s attempt and conspiracy convictions. Credibility determinations are uniquely within the jury’s province; and, we defer to their determinations and the verdict if the evidence can support varying inferences. See, e.g., United States v. Cruz-Kuilan, 75 F.3d 59, 62 (1st Cir.1996); United States v. Gonzalez-Torres, 980 F.2d 788, 790 (1st Cir. 1992). Here, the record clearly supports the verdict. That the jury chose to believe the testimony presented by the government, particularly that of Schaller, and disbelieve that presented by the defense was well within its province. As part of our sufficiency of the evidence review, we must determine whether the requisite jurisdictional element is met. Because it constitutes a jurisdictional predicate of the substantive offense, this “jurisdictional element,” like other elements of the offense, must be proved to the jury beyond a reasonable doubt. See Pappadopoulos, 64 F.3d at 524; Medeiros, 897 F.2d at 15-17 (stating that the government need only show a de minimis connection to interstate commerce in order to satisfy this element). Thus, in order for Appellant to be found guilty under the federal arson statute, the government had to prove, among other things, that the property was either “used in” or “used in an activity affecting” interstate commerce. 18 U.S.C. § 844(i). This involves identifying for what activity or purpose the building is “used.” Cf. Medeiros, 897 F.2d at 16 (focusing on the character of a fictitious building in determining whether it was sufficiently connected to interstate commerce). On appeal, Appellant argues that there is insufficient evidence to prove that the Galleria II was a building used in or affecting interstate commerce, because under López the evidence does not prove that the building “substantially affects” interstate commerce. Because Appellant did not raise this López argument below, we review only for plain error the district court’s ruling on the sufficiency of the evidence regarding the jurisdictional element. United States v. Ola-no, 507 U.S. 725, 732, 113 S.Ct. 1770, 1777, 123 L.Ed.2d 508 (1993) (“There must be an ‘error’ that is ‘plain’ and that ‘affect[s] substantial rights.’”); United States v. Brand, 80 F.3d 560, 567-68 (1st Cir.1996) (discussing Olano). We find no plain error. At the time of the district court’s decision, López had not yet been decided and there was no reason for the district court to question the viability of Russell or Medeiros. Under Medeiros, the government need only show, and the jury need only find, a de minimis connection to interstate commerce in order to sustain a conviction under 18 U.S.C. § 844(i). Medeiros, 897 F.2d at 16-17. Here, the government presented uncontested evidence that the object of the attempted arsons was a “building” that was being “used” as a commercial establishment, the Galleria II restaurant. The jury was presented with evidence that Appellant and his partners rented the building; that the building was supplied with natural gas which traveled in interstate commerce; and that the restaurant received food supplies for its operation which traveled in interstate commerce. Indeed, Appellant conceded at oral argument that the building was used as a commercial establishment which received food supplies and natural gas for its operation that travelled in interstate commerce. The district court correctly instructed the jury that the government had to prove beyond a reasonable doubt that the Galleria II was property “used in or [sic] affected interstate or foreign commerce.” Viewing the evidence in the light most favorable to the jury verdict, this evidence more than satisfies Medeiros ’ de minimis requirement, and we therefore reject Appellant’s insufficiency of the evidence argument. See, e.g., Ryan, 41 F.3d at 364 (the de minimis standard “is easily met, even when the property is temporarily closed or vacant”); U.S. v. Menzer, 29 F.3d 1223, 1229 (7th Cir.) (finding interstate commerce connection where building used partly as commercial business received natural gas and items purchased for resale that moved in interstate commerce), cert. denied, — U.S. -, 115 S.Ct. 515, 130 L.Ed.2d 422 (1994); Medeiros, 897 F.2d at 16 (holding that rental property is per se property used in an activity affecting interstate commerce). We only add this: Even assuming López requires more than a de minimis showing, we nonetheless find that the jury was presented with sufficient evidence to support its finding that the Galleria II was a building either “used in” or “used in an activity affecting” interstate commerce. Above, we found no reason to think that López in any way undercut Russell’s conclusion that Congress has the authority to regulate arson of business property. Similarly, we find no basis to conclude that López in any way undercuts Russell’s holding that “rental property is unquestionably” an “activity” that affects interstate commerce within the meaning of 18 U.S.C. § 844(i). Russell, 471 U.S. at 862, 105 S.Ct. at 2457 (‘We need not rely on the connection between the market for residential units and the ‘interstate movement of people,’ to recognize that the local rental of an apartment unit is merely an element of a much broader commercial market in rental properties.” (quoting McLain v. Real Estate Board of New Orleans, 444 U.S. 232, 245, 100 S.Ct. 502, 510-11, 62 L.Ed.2d 441 (1980))); cf. Sherlin, 67 F.3d at 1213 (finding that building used in educational business of college was building used in an activity affecting interstate commerce). We, thus, reaffirm our holding in Medeiros that rental property is per se sufficiently connected to interstate commerce to confer federal jurisdiction under Section 844(i) and to satisfy the jurisdictional element. See Medeiros, 897 F.2d at 16. Because uncontested evidence was presented that, at the time of the attempted fires, Appellant and his partner rented the building in which the Galleria II was operated, the jury was presented with sufficient evidence to find that the building was “used in an activity affecting” interstate commerce within the meaning of 18 U.S.C. § 844(i)’s second category. Even assuming further that López undermines Russell and Medeiros’ holding regarding rental property, we would nonetheless affirm the jury’s finding. Because uncontested evidence was presented below that the building was used as a commercial establishment which received food supplies and natural gas for its operation that travelled in interstate commerce, the Galleria II also falls within 18 U.S.C. § 844(i)’s “real or personal property used in interstate ... commerce.” Because the Galleria II was property used in interstate commerce, we need not address whether its activities “substantially affect[ed]” interstate commerce. Cf. Robertson, — U.S. at -, 115 S.Ct. at 1733. In sum, because we are convinced that a rational jury could have found beyond a reasonable doubt that the government had successfully proved each of the elements, we affirm the district court’s denial of Appellant’s motions for acquittal. II. Appellant’s Motion for Mistrial Appellant also appeals the denial of his motion for a mistrial on the grounds that improper testimony was prejudicial. We review the district court’s decision for abuse of discretion. United States v. Rivera-Gómez, 67 F.3d 993, 998 (1st Cir.1995) (“The trial judge is best situated to make a battlefield assessment of the impact that a particular piece of improper information may have on a jury.”); United States v. Sepúlveda, 15 F.3d 1161, 1184 (1st Cir.1993) (“Granting or denying a motion for mistrial is a matter committed to the trial court’s discretion.”), cert. denied, — U.S. -, 114 S.Ct. 2714, 129 L.Ed.2d 840 (1994). Appellant argues that the district court abused its discretion when it denied his motion for a mistrial which he made after Schaller testified that Appellant owned “a gay night club.” The trial transcript shows that SchaUer testified on direct as follows: Q: Now, in the beginning of the restaurant when it first opened, how often did you speak with the defendant about the Galleria II Restaurant? A: On a daily basis. Q: When you say “daily basis,” was that on the phone or in person? A: Usually in person. Q: Where was that? A: At the club that he owns in Providence, Gerardo’s. Q: What type of club is that? A: A gay night club. (Transcript, Vol. 4 at 98-99). At this point, Appellant objected to the comment and moved for a mistrial on the grounds that the “comment was completely gratuitous ... [a]nd it was designed specifically to, solely to[,] inflame the passions and prejudice of this jury.” (Transcript, Vol. 4 at 99). Although the court seemed to agree with the government that the information was offered as “strictly background information,” the court was nonetheless concerned about the possibility that some jurors “may have a view that someone who runs a gay bar may not be an upstanding citizen.” (Transcript, Vol. 4 at 99-100). The court decided to speak with the jurors individually to ascertain (i) whether the juror was affected by the testimony in any way; (ii) whether the juror would remain impartial; and (iii) whether the juror would be able to render a verdict based on the evidence and the law as instructed by the court, without regard to the fact that Appellant operated a gay night club. After every juror responded that he or she would not be affected by the testimony in rendering his or her verdict, (Transcript, Vol. 4 at 101-12), the court concluded, “All right. I’m satisfied.” (Transcript, Vol. 4 at 113). At this point, and without further comment by counsel, testimony resumed. At the end of trial, Appellant did not request any additional questions be asked of the jurors or that any additional instructions be given. Based on the record, and under the guiding principle that a district court may declare a mistrial only as a “last resort,” Sepúlveda, 15 F.3d at 1184, we find that the district court’s decision “was well within the broad range of its discretion.” Rivera-Gómez, 67 F.3d at 999. The district court properly weighed the claim of impropriety and determined that it was unfounded based on his voir dire of the jurors. United States v. Hahn, 17 F.3d 502, 508 (1st Cir.1994) (“A mistrial need not be allowed absent a clear showing of prejudice.”). Moreover, the district court acted swiftly by polling the jurors immediately after the improper testimony. Sepúlveda, 15 F.3d at 1185 (“Swiftness in judicial response is an important element in alleviating prejudice once the jury has been exposed to improper testimony.”). The government argues that this polling effectively provided a curative instruction that the jurors were not to consider evidence that Appellant operated a gay night club in determining guilt or innocence. Given the questions asked and the responses received, we agree that the district court “efficaciously dispelled” any prejudicial effect of Schaller’s statement by its immediate and thorough response. See United States v. Bello-Pérez, 977 F.2d 664, 672 (1st Cir.1992) (affirming denial of motion for mistrial where “[a]ny prejudicial effect of the remark was efficaciously dispelled”). Finally, given the overwhelming evidence of guilt presented during the trial, the challenged testimony was innocuous. Bello-Pérez, 977 F.2d at 672 (denying mistrial where evidence of guilt was overwhelming). III. Appellant’s Motion for a New Trial and Motion in Limine Third, Appellant appeals the denial of his motion for a new trial, arguing that the district court abused its discretion in denying his motion in limine to exclude from evidence four tapes of recorded conversations between himself and Schaller in February, March and May 1994. As the motion for a new trial is not properly before us on appeal, we only address Appellant’s motion in limine. Appellant argued below, as he does now, that the tapes should have been excluded in their entirety from evidence because (i) their probative value was substantially outweighed by their prejudicial effect under Fed.R.Evid. 403, even after certain portions were redacted; (ii) they were improperly admitted as evidence of “other crimes, wrongs, or acts” under Fed.R.Evid. 404(b); and (iii) portions of them were partially or wholly unintelligible which thereby rendered them more misleading than helpful. Here, the court listened to the four tapes, reviewed their respective transcripts, and heard arguments of counsel on the admissibility of both the tapes and the transcripts. In denying Appellant’s motion in limine to exclude the tapes in their entirety under Fed.R.Evid. 403 and 404(b), the district court found that they were admissible as probative of the issues raised in the case and that they were “overall more relevant” than prejudicial. (Transcript, Vol. 2 at 12-13). The district court, however, did allow Appellant to make specific objections of undue prejudice. (Transcript, Vol. 2 at 13-15). After hearing argument from counsel, (Transcript, Vol. 4 at 4-47), the district court agreed with most of Appellant’s specific objections and excluded those portions. With respect to Appellant’s audibility argument, the district court only found the March 1, 1994, tape troubling in that it “seems ... just woefully inadequate for any reasonable person to understand.” (Transcript, Vol. 2-17). The district court’s concern was that the only way to understand the tape was to read the transcript which resulted in the transcript — and the Government’s view — being given too much weight. After considering alternatives and hearing arguments from counsel, the district court decided to admit the tape and allow the transcript because both parties had stipulated to the accuracy of the transcript as a true rendition of the recording. (Transcript, Vol. 2 at 4; Vol. 4 at 4). Finally, the district court gave cautionary instructions to the juxy that the tapes were evidence but that the transcripts were not. The district court also ruled that the transcripts would not be permitted during deliberations. (Transcript, Vol. 4 at 4-5). We turn to Appellant’s arguments, reviewing the district court’s decision to admit or exclude evidence under Fed.R.Evid. 403 and 404(b) for abuse of discretion. See, e.g., United States v. Frankhauser, 80 F.3d 641, 648 (1st Cir.1996); United States v. Cruz-Kuilan, 75 F.3d 59, 61 (1st Cir.1996). The same standard of review applies regarding the district court’s decision to admit the tapes over Appellant’s audibility argument. See United States v. Jadusingh, 12 F.3d 1162, 1167 (1st Cir.1994) (“As we have held on numerous occasions, a trial judge’s ruling on the admission of recordings is afforded ‘broad discretion,’ even where portions of the taped conversation are unintelligible.”). A. The Tapes’ Relevancy Evidence is excludable under Fed.R.Evid. 403 “if its probative value is substantially outweighed by the danger of unfair prejudice.” After reviewing the transcript, we find no abuse of discretion in the district court’s decision to not exclude the tapes in their entirety. In support of his argument, Appellant claims that (i) none of Appellant’s statements prove any element of the alleged crimes or show consciousness of guilt; (ii) the recorded conversations took place two years after the predicate offenses occurred; (iii) many of Appellant’s arguments were made in response to questions instigated by the government witness; and, (iv) any relevant conversations were intertwined with others that were not relevant. We find none of these arguments persuasive. As the district court found, the tapes included highly probative evidence regarding Appellant’s consciousness of guilt, including admissions. The tapes were directly relevant to the government’s theoxy regarding both Appellant’s involvement in the attempted arson and the conspiracy. Indeed, we note that Appellant’s counsel conceded as much during the hearing on the tapes’ admissibility: “I concede, Judge, that there were parts that, given the Government’s position and its interpretation, are relevant.” (Transcript, Vol. 2 at 12). For example, the Febniary 24, 1994, tape includes a conversation regarding the payment of Schaller’s legal fees. Not only did it corroborate Schaller’s testimony that Appellant assisted in the payment of Schaller’s legal fees, this conversation included evidence from which the jury could draw an inference “that this money is being paid because these gentlemen were in on the deal together.” (Transcript, Vol. 4 at 9). The March 1,1994, tape includes an admission by Appellant that he threw matches to light the fire during the first attempt: “You weren’t there when I threw the [expletive] matches the first time.” The March 4, 1994, tape includes an adoptive admission by Appellant regarding his attempts to burn the restaurant during a conversation about whether Appellant had told anyone about those efforts. While Appellant denies telling anybody else about his efforts, he responds to Sehaller’s questions directly without ever disputing the veracity of what Sehaller’s questions imply — that Appellant “tried to burn it.” The May 25, 1994, tape provides evidence of the conspiracy between Schaller and Appellant. The conversation demonstrates that, although they were confused as to their recollection of what they believed to be their respective roles, they clearly had conspired to bum the restaurant. This sampling of each of the four tapes clearly shows that, contrary to Appellant’s claims, the recordings include statements by Appellant that are directly probative of both attempts and the conspiracy. Appellant also points to the fact that the recorded conversations occurred two years after the alleged offenses, arguing that the recordings are neither closely intertwined with the charged offenses nor helpful in establishing Appellant’s intent to commit the crimes charged. Appellant cites to three cases addressing the admissibility of evidence under Fed.R.Evid. 404(b). See United States v. Huff, 959 F.2d 731, 736 (8th Cir. 1992); United States v. Brookins, 919 F.2d 281, 286 (5th Cir.1990); United States v. Hodges, 770 F.2d 1475, 1480 n. 4 (9th Cir. 1985). We agree with these cases that proximity in time is a factor to be considered in determining relevancy under Fed.R.Evid. 404(b) of “other crimes, wrongs, or acts.” See, e.g., United States v. Fields, 871 F.2d 188, 197 (1st Cir.1989) (“Probative value must be considered in light of the remoteness in time of the other act and the degree of the resemblance to the crime charged.”); United States v. Currier, 836 F.2d 11, 17 (1st Cir. 1987) (noting that the prior bad acts were both close in time and in nature to the crime charged). In addition, Appellant also points out that the tapes here are distinguishable from those admitted in Currier, based on the fact that the recorded conversations in that case occurred immediately prior to and after the crime charged and were, thus, found to “help[] establish appellant’s intent to commit the crime charged.” Id. Because the conversations here occurred two years after the predicate offenses, Appellant contends that the tapes cannot be said to be so “closely intertwined” with the predicate offenses so as to help establish Appellant’s intent to commit the crimes charged. We are unswayed by Appellant’s arguments. Here, as we discuss below, no evidence of prior bad acts was admitted in this ease; and, because Appellant has not cited to any cases holding that proximity in time is a prerequisite for determining relevance under Fed.R.Evid. 403, and because we have not found any, we are unconvinced that the timing of the conversations is of any consequence or otherwise undermines their strong relevance. See, e.g., United States v. Perkins, 926 F.2d 1271, 1279-80 (1st Cir.1991) (finding no error in admission of post-conspiracy statements made to a government informant where court found statements were an admission corroborating trial testimony and reflected complicity and consciousness of guilt). Even assuming, arguendo, that proximity must be considered in determining relevance, we nonetheless find that even though the conversations occur two years after the attempt and conspiracy, they are “closely intertwined with the charged offense[s] ... [and] [ ] provid[e] ... significant contextual material” for the jury. Currier, 836 F.2d at 17 (citations omitted). As discussed above, while they do not necessarily show Appellant’s intent to commit the attempted arson or to enter into a conspiracy, they do show Appellant’s consciousness of guilt and complicity as well as the existence of a conspiracy. See Perkins, 926 F.2d at 1279-80. While not all evidence with probative value is admissible, we do not find that its value is “substantially outweighed by the danger of unfair prejudice.” Fed.R.Evid. 403. In reviewing the balancing undertaken by the district court, we give great deference to the district court’s judgment, and “[o]nly in exceptional circumstances will we reverse the exercise of a district court’s informed discretion vis-a-vis the relative weighing of probative value and unfairly prejudicial effect.” Currier, 836 F.2d at 18 (quoting United States v. Griffin, 818 F.2d 97, 101-02 (1st Cir.), cert. denied, 484 U.S. 844, 108 S.Ct. 137, 98 L.Ed.2d 94 (1987)). Based on our review of the record, we do not find that the probative value of the tapes — as edited— was outweighed by unfairly prejudicial evidence. See, e.g., United States v. Muñoz, 36 F.3d 1229, 1233 (1st Cir.1994) (noting that the question under Rule 403 is one of unfair prejudice, not prejudice alone); Currier, 836 F.2d at 18 (“Unfairly prejudicial evidence is evidence ... that ‘triggers [the] mainsprings of human action [in such a way as to] cause the jury to base its decision on something other than the established proposition in the case.’ ”) (quoting 1 Weinstein’s Evidence § 403[03], 36-39 (1986)). Neither the fact that many of Appellant’s remarks were made in response to questions or comments by the government witness, nor that relevant conversations were intertwined with non-relevant ones, persuades us to reach a different conclusion. Even the fact that the recordings reveal that Appellant had initially wanted to hire “a guy from organized crime so to speak” to bum the restaurant, (Transcript, Vol. 4 at 32), or that Appellant tells Schaller what to say about pouring the gasoline, (Transcript, Vol. 4 at 44), does not make them unfairly prejudicial. Finally, we do not find that any “exceptional circumstances” exist which warrant reversal of the district court’s rulings. B. The Tapes’ Prior Bad Act Evidence We find Appellant’s reliance on Fed. R.Evid. 404(b) to be irrelevant on appeal. While the transcript of the pre-trial hearing regarding the admissibility of the tapes shows that there were references to previous fires which arguably fall within Fed.R.Evid. 404(b), the record shows that these references were excised by agreement of the parties. (Transcript, Vol. 4 at 21). Not only does Appellant not specify on appeal what “other crimes, wrongs, or acts” under Fed. R.Evid. 404(b) were erroneously admitted into evidence, we find no mention of any in the portions that were admitted into evidence. Accordingly, we do not address this argument further. C. The Tapes’ Audibility Lastly, as to Appellant’s audibility argument, in exercising its broad discretion in ruling on the admissibility of tape recordings, even where portions are unintelligible, Font-Ramírez, 944 F.2d at 47, the district court “must decide whether ‘the inaudible parts are so substantial as to make the rest more misleading than helpful.’ ” Id. (citations omitted) (quoting Gorin v. United States, 313 F.2d 641, 652 (1st Cir.), cert. denied, 374 U.S. 829, 83 S.Ct. 1870, 10 L.Ed.2d 1052 (1963)). While the district court found that there were segments of poor audio and static, the district court nonetheless decided to admit them. The district court was swayed by the fact that the parties stipulated to the accuracy of the transcript as a true recording of the tapes. We are similarly swayed and find no abuse of the court’s broad discretion, even as to the March 1, 1994, tape about which the district court was most concerned. Based on our review of the transcript, we disagree with Appellant’s claim that the inaudible parts, when taken as a whole, were so substantial as to make the rest more misleading than helpful, because the transcript clearly evidences that sufficient portions of the tapes, including statements by both Schaller and Appellant, are audible. As discussed earlier, these segments are relevant because they include, inter alia, admissions by Appellant, tending to show consciousness of guilt and corroborate trial testimony. Furthermore, the district court gave a cautionary instruction to the jury that not only informed them that the tapes, but not the transcript, were evidence, but also that the jurors had to draw their own conclusions regarding their content and probative value based on what they themselves heard on the tapes. United States v. Carbone, 798 F.2d 21, 26 (1st Cir. 1986) (finding that the judge’s handling of the transcript was in accord with the law where the record shows that the judge carefully instructed the jurors that the tapes, not the transcripts, were evidence and that any differences between the two must be resolved in favor of what was heard on the recording). Based on the record, and particularly in light of Appellant’s stipulation to the accuracy of the transcript as a true recording of the tapes, we find no abuse of discretion by the district court in admitting the tapes over Appellant’s audibility objection. IV. Appellant’s Sentence Finally, Appellant appeals his sentence imposed by the district court pursuant to the federal arson guidelines. See U.S.S.G. § 2K1.4(a)(l)-(4). The arson guidelines provide, in pertinent part: (a) Base Offense Level (Apply the Greatest): (1) 24, if the offense (A) created a substantial risk of death or serious bodily injury to any person other than a participant in the offense, and that risk was created knowingly; ... (2) 20, if the offense (A) created a substantial risk of death or serious bodily injury to any person other than a participant in the offense; ... (3) 2 plus the offense level from § 2F1.1 (Fraud and Deceit) if the offense was committed in connection with a scheme to defraud; or (4) 2 plus the offense level from § 2B1.3 (Property Damage or Destruction). U.S.S.G. § 2K1.4; see U.S.S.GApp. C, Amendment 330 (restructuring the arson guidelines). New language in the Commentary, Application Note 2, provides that “[c]reating a substantial risk of death or serious bodily injury includes creating that risk to firefighters and other emergency and law enforcement personnel who respond to or investigate an offense.” See, e.g., United States v. Turner, 995 F.2d 1357, 1365 (6th Cir.1993) (finding that endangering firefighters is an appropriate factor); United States v. Grimes, 967 F.2d 1468, 1471 (10th Cir.), cert. denied, 506 U.S. 927, 113 S.Ct. 355, 121 L.Ed.2d 269 (1992) (noting that several other circuits had come to the same conclusion). Appellant challenges the district court’s sentence on three separate grounds. We address them in turn, reviewing findings of fact for clear error, mindful that they need only be supported by a preponderance of the evidence, and reviewing questions of law de novo, including the scope and applicability of a relevant guideline. See 18 U.S.C. § 3742(e); United States v. Martínez-Martínez, 69 F.3d 1215, 1224 (1st Cir.1995); United States v. Thompson, 32 F.3d 1, 4 (1st Cir.1994). A. The “Fraud or Deceit” Base Offense Level First, Appellant contends that the district court should have applied U.S.S.G. § 2K1.4(a)(3), which requires computation of the base offense level as 2 plus the base offense level for “Fraud and Deceit.” Appellant argues that the overwhelming evidence at trial established that his primary purpose was to defraud the insurance company and that Appellant, while creating some risk of death or serious bodily injury by pouring gasoline, did not knowingly create a substantial risk. While the record does indicate that Appellant participated in a scheme to defraud the insurance company, we conclude that the district court properly chose subparagraph § 2K1.4(a)(l) based on its specific finding — -which, as we discuss below, was not clearly erroneous — that Appellant knowingly created a substantial risk of death or serious bodily injury to persons other than the participants in the attempted arson. See Grimes, 967 F.2d at 1472 (holding that district court properly rejected application of fraud guideline, § 2K1.4(a)(3), and properly applied § 2K1.4(a)(2) in ease involving defendant’s effort to obtain insurance through arson where defendant created substantial risk of injury or death). The arson guideline instructs that the base offense level is determined by selecting the highest level from among four choices. Section 2K1.4(a)(l)-(4); United States v. Mizrachi, 48 F.3d 651, 655 (2d Cir.1995). The Government contends that applying § 2K1.4(a)(3) would only yield a base offense level of 19, less than that under § 2K1.4(a)(l), which is 24. Appellant does not dispute this calculation or otherwise present his own § 2K1.4(a)(3) calculation, nor was there any discussion of this issue during the sentencing hearing. Assuming, without deciding, that calculation under § 2K1.4(a)(3) would have yielded only a base offense level of 19, we conclude that the. district court correctly applied § 2K1.4(a)(l) because it yielded the highest base offense level based on its finding that Appellant knowingly created a substantial risk of bodily injury. Cf. Mizrachi, 48 F.3d at 656 (affirming district court’s application of § 2K1.4(a)(3) in sentencing defendant for arson, mail fraud, and money laundering offenses where facts yielded an initial base offense level of 35). B. Knowing Creation of a Substantial Risk Second, Appellant argues that the district court’s finding that Appellant knowingly created a substantial risk of death or serious bodily injury to any person other than a participant in the offense is not supported by a preponderance of the evidence. Whether a defendant knowingly created a substantial risk of death or serious bodily injury within the meaning of section 2K1.4 of the Guidelines raises an issue of first impression in that this court has not previously determined what level of knowledge is required under § 2K1.4(a)(l)(A). At the outset, we note that this determination involves a two-step inquiry. A court must first ask whether the defendant’s actions created a substantial risk of death or serious bodily injury and then decide whether the defendant acted knowingly in creating that risk. See United States v. Karlic, 997 F.2d 564, 568-69 (9th Cir.1993) (stating that the first inquiry is objective and the second is subjective). 1. The Substantial Risk ... Leaving'aside the question of knowledge for the moment, we conclude first that the district court did not clearly err in finding that Appellant created a substantial risk of death or serious bodily injury to any pérson other than a participant in the offense. The district court based its finding primarily on the PSR, which indicated, inter alia, that the presence of gasoline created the potential for a fire or explosion. According to the PSR, a fuel air explosion could have occurred had “a heat source been introduced within a specific danger range between the place where thé gasoline was poured and anyplace within the building where the odor of gasoline was detected,” (PSR, at 22), and that “because the gasoline was poured in a confined area which contained electrical outlets, an electrical spark or other heat source could have ignited the vapors in the confined area at any time,” (PSR, at 23). Although the evidence indicates that Appellant only planned to ignite the fire after the restaurant closed, the district court concluded that the potential for a fuel air explosion or for a fire to start accidentally created a substantial risk of death or serious bodily injury to the occupants of the building at the time of the pouring of the gasoline in the attic as well as to firefighters and others who would respond to the incident. We find no clear error in this finding of substantial risk to patrons and firefighters. It was properly based on both the PSR and the sentencing judge’s common sense understanding — which Appellant conceded during the sentencing hearing was appropriate — of the risks associated with pouring an accelerant to start a fire in an occupied building where there was the potential for a fuel air explosion to occur or for a fire to start accidentally. See Medeiros, 897 F.2d at 20 (relying on common sense in finding under earlier arson guidelines that defendant conspired “to cause the kind of fire that recklessly would endanger others.”). As the district court correctly noted in response to Appellant’s insistence that there was no risk created because no fire actually occurred, (Sentencing Transcript, pages 19-22), the Guidelines speak of “risk.” “The fact that fortuitously no one was injured and extensive damage did not result [because no fire or explosion actually occurred] does not further [A]ppellant’s contention that he did not ... create a substantial risk of death or serious bodily injury.” United States v. Honeycutt, 8 F.3d 785, 787 (11th Cir.1993). Furthermore, in light of the federal arson guidelines’ commentary, see U.S.S.G. § 2K1.4, Application Note 2, we find no clear error in the district court’s finding of substantial risk given its finding that firefighters “could have been blown to smithereens” had a spark ignited the gasoline vapors (Sentencing Transcript, at 20). See, e.g., Turner, 995 F.2d at 1365; Grimes, 967 F.2d at 1471. While “all fires present some danger to firefighters required to extinguish -it, ... [w]here a spectacular fire is planned near an occupied building, a finding of reckless endangerment to firefighters would be based on a common sense understanding of the risks of putting out a major fire when rescue attempts are likely to be necessary.” Medeiros, 897 F.2d at 20. Similarly, here, although there is no evidence that Appellant planned a “spectacular fire,” the sentencing judge’s finding of substantial risk in this ease was based on his — and, again, our — common sense understanding of the risks associated with using an accelerant in an occupied building to start a fire where there was the potential for a fuel air explosion to occur or for a fire to start accidentally. 2. ... Knowingly Created Next, we must decide whether the district court clearly erred when it found that Appellant knowingly created this substantial risk. While we review the court’s factual finding for clear error, the definition of a Guidelines term is a question of law which we review de novo. Martínez-Martínez, 69 F.3d at 1224. Looking first to the statute, we note that the two highest base offense levels in the federal arson guidelines, § 2K1.4(a)(l) and § 2K1.4(a)(2), contain almost identical language. The latter, for which there is a base offense level of 20, applies to the creation of a substantial risk of death or serious bodily injury. The former, for which there is a base offense level of 24, applies to the knowing creation of such a risk. This structure clearly suggests that there must be a meaningful distinction between the two sections. See Honeycutt, 8 F.3d at 787 (noting that “[c]learly it was intended for there to be a distinction between the two sections”). Given the structure of the arson guidelines, we conclude that § 2K1.4(a)(l)(A) requires that the district court make a specific finding that the defendant “knowingly” created a substantial risk of death or serious bodily injury, as opposed to merely finding that defendant recklessly (or negligently) created such a risk which would more appropriately trigger application of § 2K1.4(a)(l)(B). Apart from this rather straightforward observation, no guidance is gleaned from the Sentencing Guidelines, as “knowingly” is not defined. In addition, the usual rule of giving an undefined statutory term its plain meaning provides little direction given that “ ‘[k]nowledge’ means different things in different contexts.” United States v. Spinney, 65 F.3d 231, 236 (1st Cir.1995). Our own precedent is of little help because, while this court has addressed the application of the federal arson guidelines, see Medeiros, 897 F.2d at 18 (applying former U.S.S.G. § 2K1.4(b)(2) and affirming district court’s finding that defendant “recklessly endangered the safety of another”); see also, United States v. Flowers, 995 F.2d 315, 316 (1st Cir.1993) (involving but not discussing application of § 2K1.4); United States v. Johnson, 952 F.2d 565, 585 (1st Cir.1991) (same), it has never addressed what level of knowledge is required under the highest offense level where the substantial risk was created knowingly by the defendant. Turning to our fellow circuits, we note that the Ninth Circuit, and later the Eleventh Circuit, adopted the definition of “knowingly” as used in the Model Penal Code (the “MPC”) when applying § 2K1.4. See Honeycutt, 8 F.3d at 787; United States v. Karlic, 997 F.2d 564, 569 (9th Cir.1993). Drawing from the MPC’s definition, the,Ninth Circuit held that “a defendant can be found to have ‘knowingly' created a substantial risk of death or serious bodily injury under § 2K1.4 only if the defendant was aware that a substantial risk of death or serious bodily injury was ‘practically certain’ to result from the criminal act.” Karlic, 997 F.2d at 569; accord, Honeycutt, 8 F.3d at 787. We note that other courts have neither explicitly defined “knowingly” nor adopted the MPC’s definition, apparently finding it unnecessary where the district court could clearly conclude from the facts whether the defendant knew his actions created a substantial risk of death or serious bodily injury. For example, in United States v. Markum, 4 F.3d 891 (10th Cir.1993), the court found that a fire set with gasoline during business hours which put firefighters in severe jeopardy because of the ferocity of the fire and the risk of explosion constituted “circumstances [which] more than justified the district court’s finding that [defendant], as a co-conspirator, knowingly created a substantial risk of death or serious bodily injury.” Id. at 896-97. Similarly, in United States v. Turner, 995 F.2d 1357 (6th Cir.), cert. denied, 510 U.S. 904, 114 S.Ct. 282, 126 L.Ed.2d 232 (1993), the district court concluded that defendant’s actions could fit under either § 2K1.4(a)(l)(A) or (B). As to the defendant’s knowledge, the court found that defendant knowingly created the substantial risk given that people in the residence adjacent to the burning building were likely to be asleep and windy conditions would cause the fire to spread quickly. Id. at 1365. The court in Turner also found that defendant “should have known” that he was placing firefighters at a substantial risk by committing the arson in weather conditions that would make extinguishing the fire extremely difficult. Id. As this relevant case law provides at least two distinct approaches, we find it helpful when considering the question of “knowledge” to recall that “the length of the hypothetical knowledge con