Full opinion text
TORRUELLA, Chief Judge. This appeal arises from a sixty-six count criminal indictment charging the eight appellants — Rafael Collazo-Aponte, Heriberto Ortiz-Santiago, Andrés Colón-Miranda, Edwin Ortiz-Figueroa, David S. Martínez-Vélez, Jorge Merced-Morales, Ramón A. Ríos-Ríos, and Edwin Rosario-Rodrí-guez — with numerous offenses related to a decade-long, multi-drug-dealing conspiracy based in the Virgilio Dávila public housing project in Bayamón, Puerto Rico. In addition to the drug conspiracy charges, the indictment also charged that between April 1993 and June 1994 over a dozen of the originally named co-conspirators engaged in a war of revenge, triggered by the February 23, 1993 murder of Richard Muñoz-Candelaria. This' drug war resulted in the murder of at least seven individuals. On February 16, 1998, a jury returned guilty verdicts as to all appellants on all counts. This appeal followed. After carefully examining the record and the law, we affirm in part and reverse and remand in part. PROCEDURAL HISTORY On June 26, 1997, a grand jury empaneled in the United States District Court for the District of Puerto Rico returned a third superseding indictment in criminal case number 95-029(JAF). Count 1 charged appellants with conspiracy to possess with intent to distribute cocaine base, cocaine, and heroin. See 21 U.S.C. §§ 841, 846. Count 65 charged appellants with using and carrying a firearm during and in relation to a drug conspiracy. See 18 U.S.C. § 924(c). Count 51 charged appellants Colón-Miranda, Ortiz-Santiago, Ortiz-Figueroa, and Martínez-Vélez with conspiring to Mil while engaged in a drug conspiracy. See 21 U.S.C. §§ 846, 848(e)(1)(A). Additional counts charged appellants Rosario-Rodríguez (Count 52), Colón-Miranda (Counts 53-59 and 62), Ortiz-Santiago‘ (Count 53), Ortiz-Figueroa (Count 53), and Martínez-Vélez (Counts 57 and 58) with intentionally killing or attempting to kill while engaged in a drug conspiracy. See 18 U.S.C. § 2; 21 U.S.C. §§ 846, 848(e)(1)(A). These charges also alleged liability pursuant to Pinkerton v. United States, 328 U.S. 640, 66 S.Ct. 1180, 90 L.Ed. 1489 (1946). Finally, Counts 60-64 charged Colón-Miranda with attempting to kill and then killing Rafael Cotto-Fuentes in order to prevent him from (1) communicating with law enforcement officers and (2) testifying for the prosecution. See 18 U.S.C. §§ 2,1512(a)(1)(A), (C). On November 5, 1997, the prosecution moved the district court to empanel an anonymous jury. On November 13, 1997, the court conducted a “Jury Orientation” without the parties or counsel being present and excused several prospective jurors. The court then granted the government’s request for an-anonymous jury over the objection of Colón-Miranda. Prior to trial, the court also denied motions to sever filed by appellants Ríos-Ríos and Collazo-Aponte. Trial commenced on November 17, 1997. At that time, the district court ruled that all rulings applied to all defendants and motions joining co-defendants’ motions were unnecessary. The court also denied a motion to reconsider its decision to empanel an anonymous jury. On February 16, 1998, the jury returned guilty verdicts as-to all appellants on all counts. The court sentenced Ortiz-Santiago, Ortiz-Figueroa, and Martínez-Vélez to concurrent terms of life imprisonment on multiple counts and a consecutive ten-year term on Count 65; Colón-Miranda to concurrent terms of life imprisonment on multiple counts, a concurrent twenty-year term on Count 66, and a consecutive ten-year term on Count 65; Rosario-Rodrí-guez to concurrent terms of life imprisonment on Count 1 and twenty years on Count 52, as well as a consecutive ten-year term on Count 65; Collazo-Aponte, Ríos-Ríos, and Merced-Morales to 151, 293, and 360 months imprisonment, respectively, on Count 1 and, with respect to Collazo-Aponte and Merced-Morales, a consecutive ten-year term on Count 65. FACTUAL BACKGROUND We review the facts in a criminal case in the light most favorable to the verdict. See, e.g., United States v. Bartelho, 71 F.3d 436, 438 (1st Cir.1995). I. Overview At trial, the prosecution offered evidence of a drug distribution organization led by Israel Santiago-Lugo that began in the Virgilio Dávila housing project in Bayam-ón, Puerto Rico, and later expanded to several drug distribution points in northern Puerto Rico. The government’s evidence included the testimony of five cooperating witnesses: brothers Wilfredo and David Martinez-Matta, Billy Ramos-Rod-ríguez, José Ibáñez-Maldonado, and Marcos Hidalgo-Meléndez. These witnesses testified that in the mid-1980s Santiago-Lugo cultivated a group of employees who processed and packaged cocaine and heroin at apartments, known as “mesas,” for delivery to various drug distribution points. The evidence indicated that trusted operatives managed the distribution points and lower level employees handled the street-level distribution. On February 28, 1998, the Santiago-Lugo drug organization splintered into rival factions when the Rosario-Rodríguez brothers murdered Richard Muñoz-Candelaria. A series of retaliatory murders ensued as Santiago-Lugo and those loyal to him engaged in hunting expeditions (“cacerías”) to kill the Rosarios. II. Drug Packaging at the Mesas At trial, the witnesses for the prosecution testified as to their and the appellants’ involvement in the Santiago-Lugo drug mesas. Wilfredo Martinez-Matta stated that in 1986 and 1987 he worked at two drug mesas located in hotels. At that time, he also packaged cocaine at his mother’s house. Ramos-Rodríguez and David Martinez-Matta testified that they also packaged drugs at the Martinez-Matta house, and David Martinez-Matta stated that Santiago-Lugo, Colón-Miranda, and brothers Ortiz-Santiago and Ortizr-Figuer-oa participated. Wilfredo Martinez-Matta and Ramos-Rodríguez testified that in 1989 a condominium in Reina del Mar served as a mesa. Hidalgo-Meléndez testified that Colón-Miranda, Ortiz-Santiago, and Ortiz-Figueroa packaged drugs there in the early 1990s. Wilfredo Martinez-Matta stated that he packaged cocaine there once in 1989, and further stated that Ortiz-Santiago, a drug user, “tested” drug quality at this location. Ramos-Rodríguez, who rented the Reina del Mar mesa for four to five months, indicated that the drug organization packaged one-eighth-kilogram quantities of cocaine at each session in the Reina del Mar mesa and that he or Santiago-Lugo would transport the drugs to Dá-vila for storage and distribution. In the early 1990s, Wilfredo Martinez-Matta worked at two mesas in the Costa del Mar condominium complex. At these locations, he processed cocaine with Ramos-Rodríguez and heroin with Ríos-Ríos. Wilfredo Martinez-Matta also stated that (1) the organization packaged kilogram quantities of cocaine and one-eighth kilograms of heroin at each session and (2) Ríos-Ríos once obtained one kilogram of cocaine for Santiago-Lugo from a supplier. Ramos-Rodríguez recalled that the organization used the Costa del Mar mesas from 1990 to 1991, that he processed heroin and cocaine once or twice a week for four or five months there, and that he was paid $150 for each one-eighth kilogram of cocaine packaged. He added that Ortiz-Santiago delivered drugs to the mesa, occasionally with Santiago-Lugo. Ortiz-Santiago also procéssed drugs and tested their purity. Wilfredo Martinez-Matta, David Martinez-Matta, and Ramos-Rodríguez also testified that Ríos-Ríos rented a mesa at the Los Pinos condominium complex in Isla Verde. All three witnesses, in addition to Colón-Miranda, Ortiz-Santiago, Ortiz-Figueroa, and’ Ríos-Ríos, processed heroin there. According to the testimony presented at trial, the organization processed quarter-kilogram quantities of heroin and kilogram quantities of cocaine there on a weekly basis. Hidalgo-Melén-dez also recalled packaging drugs at Los Pinos and once saw Ríos-Ríos deliver cocaine there. Further, the rental agreements for the Los Pinos mesa indicated that Ríos-Ríos rented the apartment and listed Santiago-Lugo as his employer and reference. Defense witness Marta Arron-do-Diaz, who owned the-Los Pinos apartment, stated that she rented the apartment to Ríos-Ríos and Santiago-Lugo for a one year term in March 1991. The trial testimony identified three additional mesas: an apartment in Condado where Wilfredo Martinez-Matta worked with Ortiz-Santiago, a condominium in the Villa del Mar complex in Isla’Verde, and a Coral Beach condominium rented by Co-lón-Miranda. Wilfredo Martinez-Matta recalled seeing Santiago-Lugo, Colón-Mi-randa, Ramos-Rodríguez and others packaging heroin in bags marked with the name “cristal” at the Coral Beach condominium. Ramos-Rodríguez testified that Santiago-Lugo moved operations to the Coral Beach condominium in 1991. There, Santiago-Lugo, Colón-Miranda, Ortiz-Santiago, and others packaged two or three ounces of heroin two or three times each week. III. Drug Distribution Points Wilfredo Martinez-Matta testified that by the time the drug operation was located at the Coral Beach mesa in 1991, the organization had drug points in Manatí, Vega Baja, Arecibo, Campo Alegre, and Sabana Seca. Wilfredo Martinez-Matta worked at the Vega Baja drug point where he sold fifty packages of heroin every ten days; each package, obtained for $75 and sold for $100, contained ten “decks” of heroin. Co-lón-Miranda and Richard Muñoz-Candela-ria occasionally supervised the Vega Baja drug point. Later, Wilfredo Martinez-Matta supervised a drug point in Manatí where he sold approximately one hundred packages of heroin every three days and also sold marijuana and vials of crack. David Martinez-Matta supervised one of the Arecibo drug points where he sold heroin, cocaine, crack, and marijuana from 1991 to 1995. He testified that Colón-Miranda would deliver the drugs for distribution. He also stated that on two occasions he saw Colón-Miranda make deliveries to Luis Rosario-Rodríguez. In 1990, José Ibáñez-Maldonado began to accompany Colón-Miranda on drug deliveries to the drug distribution points; later, Ibáñez-Maldonado also assisted with packaging drugs at Colón-Miranda’s Dora-do home and at a mesa in the King’s Court condominium. After the Santiago-Lugo/Rosario-Rodri-guez conflict erupted in February 1993, the exchange of drugs and money moved from an apartment in the Dávila housing project to Merced-Morales’ bar, “Chom-pa,” in Monacillos. Both Wilfredo and David Martinez-Matta testified that on numerous occasions they delivered money there and obtained drugs from Merced-Morales and Collazo-Aponte, including kilogram quantities of crack. IV. The Rosario-Rodríguez Brothers The Rosario-Rodríguez brothers, Richard, Edwin, and Luis, controlled a drug distribution point at the Dávila housing project outside of Building 17. By mid-1991, the brothers were selling Santiago-Lugo’s heroin. In August 1991, Santiago-Lugo granted the Rosario brothers exclusive distribution rights for his cocaine at Dávila. Ramos-Rodríguez testified that Edwin Rosario-Rodríguez controlled the crack cocaine distribution at Dávila and was responsible for getting heroin to the street dealers. He further stated that during this time he saw Edwin Rosario-Rodríguez in possession of a firearm at Dávila. Similarly, Hidalgo-Meléndez testified that Edwin Rosario-Rodríguez went to Rosa Morales-Santiago’s apartment to pick up drugs, and identified numerous drug transactions in the drug ledgers under Edwin’s nickname “Indio.” By 1992, however, Edwin Rosario-Rod-ríguez’ ability to run the drug point was in question, and Santiago-Lugo removed him from his position as a “point owner.” Nevertheless, the Rosarios were still allowed to sell packages of heroin and cocaine. Hidalgo-Meléndez testified that the agreement between Santiago-Lugo and the Rosario brothers continued until February 28, 1993, when the Rosario brothers murdered Richard Muñoz-Candelaria. The prosecution also offered evidence of the following incident involving Edwin Rosario-Rodríguez. On July 3,1992, a police officer witnessed Edwin Rosario-Rodrí-guez holding a Calico pistol in the Dávila housing project. The officer followed him into Building 17. Edwin Rosario-Rodrí-guez discarded the weapon by the entrance, and the officer seized it. In the stairway, the officer also seized a white bag that had been carried by a second individual that contained transparent plastic vials commonly used to package crack cocaine. The bag field-tested positive for cocaine. Edwin Rosario-Rodríguez ran into an apartment with a metal door (the other apartments on the floor had wooden doors), and the officer heard the toilet flushing. The officer entered the' apartment by using a balcony and later seized over $1,000 in cash. V. Drug Ledgers Both Wilfredo and David Martinez-Mat-ta testified about drug transactions at the Dávila apartment of Rosa Morales-Santiago. In his testimony, Wilfredo Martinez-Matta stated that Morales-Santiago would count the heroin proceeds and record them in a notebook. Similarly, Hidalgo-Melén-dez testified that Morales-Santiago recorded drug transactions in a black school notebook and, later, a brown notebook. After examining two notebooks seized from Morales-Santiago’s Dávila apartment in 1991, Hidalgo-Meléndez stated that units marked “c” in the-.notebooks represented “cristal” and that each package contained ten bags of heroin. An expert witness testified that the notebooks were consistent with those kept by an illicit drug organization. He opined that the “product” was calculated in units and that the “c” units sold for $75. He noted that together the notebooks reflected sales of at least $3.5 million during one year. VI. The Murder of Richard Muñoz-Candelaria At trial, witnesses for the prosecution offered the following account of the February 28, 1993 murder of Richard Muñoz-Candelaria. Wilfredo Martinez-Matta testified that he, Muñoz-Candelaria, and an individual named Jerry were at the Rosario drug point in Dávila the day Muñoz-Candelaria was killed. Santiago-Lugo had sent Muñoz-Candelaria to inform “Liquio” (Luis Rosario-Rodríguez) that he wanted his heroin and his money back. Liquio was “upset” and told .Muñoz-Candelaria to “forget about it.” Edwin Rosario-Rodrí-guez was there, holding an automatic pistol. Colón-Miranda and a co-conspirator identified as “El Gato” arrived, and Colón-Miranda sent Wilfredo Martinez-Matta to deliver some money to Santiago-Lugo. When Wilfredo arrived at Santiago-Lugo’s house, Santiago-Lugo answered a ringing telephone. He heard gun shots over the telephone, and he ordered, Wilfredo. to return to the Rosario drug point. Santiago-Lugo then paged Wilfredo and directed him to pick up Colón-Miranda at a bus stop. When he arrived, Colón-Miranda told him that Liquio killed Muñoz-Cande-laria. Ramos-Rodríguez testified that he was in Dávila on the afternoon of the murder. He stated that he had declined to join Colón-Miranda and Muñoz-Candelaria when they went to talk to Liquio, going instead to his mother-in-law’s apartment. There, he heard a gunshot, and then a few seconds later, he heard two different series of shots. He ran out onto a balcony, saw people running away, and heard some people shout, “Liquio killed him” and “whoever talks, I’ll kill them.” Later that day, Colón-Miranda told David Martinez-Matta that El Gato and Muñoz-Candelaria were talking to Liquio. Muñoz-Candelaria attempted to hand Li-quio his phone when Liquio started to shoot him. Colón-Miranda and El Gato did not have time to draw their weapons, so they ran away. At that time, “Indio” (Edwin Rosario-Rodríguez) came over to where Muñoz lay, and both Edwin and Luis Rosario-Rodríguez shot Muñoz-Candelaria again. Officer Sánchez-Ramos testified that he found the victim lying on top of a cellular telephone that was still turned on. The autopsy report showed that Muñoz-Cande-laria was shot twenty-nine times. Blood and urine tests indicated the presence of alcohol, and urine and nasal swab tests were positive for cocaine and a cocaine metabolite. A forensics expert testified that the victim had been shot with two types of bullets, indicating that two' guns were used in the murder. After the murder, Colón-Miranda and Wilfredo Martinez-Matta attended the first of several meetings to discuss “going to war” over the Dávila drug point. At these meetings, members of the Santiago-Lugo organization discussed and planned cacerías to kill the Rosarios. At a second meeting in Isla Verde, Santiago-Lugo and Colón-Miranda prepared weapons for the cacerías. VII. The Hunting Expeditions (“Cace-rías”) A. The Murder of Reynaldo Pacheco-Aponte At a subsequent meeting held in an apartment in Dorado, the Martinez-Matta brothers, Hidalgo-Meléndez, El Gato, Santiago-Lugo, and Colón-Miranda planned how they would enter Dávila and kill the Rosarios. During the meeting, Colón-Mi-randa telephoned Ortiz-Santiago, and it was agreed that Ortiz-Santiago and Ortiz-Figueroa would keep Colón-Miranda informed as to the Rosarios’ precise location within Dávila. On April 19, 1993, the group drove to Dávila after receiving a call from Ortiz-Santiago. Colón-Miranda and El Gato, armed with AR-15 rifles, entered the housing project through the back door of a business while the others drove into the complex. When they all returned to their cars, and at a later meeting, Colón-Mi-randa talked about how he killed “El Pacheco.” At the scene of the crime, law enforcement officers recovered 100 casings fired from AR-15 rifles. A distressed resident informed an officer at the scene that “they ran off through Paradero 23” and “they had masks.” He also said that one of those who ran off was injured and wearing white pants and a mask. The officer located Ortiz-Santiago and Ortiz-Figueroa walking together on a side street near the Paradero and arrested and searched them. Ortiz-Figueroa had a bag containing firearms and ammunition, a rock of heroin or cocaine, a cellular telephone, a glove, two masks, and a firearm on his person. The officer saw blood on one of the masks and on the clothes of Ortiz-Figueroa who appeared to have a hand injury. Wilfredo Martinez-Matta was not at the cacería; instead, he was obtaining three pounds of marijuana from Merced-Mor-ales’ business. Some of those involved, however, later met at his house. There, Colón-Miranda admitted to participating in the hunt and El Gato admitted killing Pacheco-Aponte. At yet another meeting, the co-conspirators discussed David Martinez-Matta shooting haphazardly during the cacería and that, as -a result, “Erick [Ortiz-Santiago] could not come out.” Hidalgo-Meléndez learned of the murder on the news. He was informed of the details at a meeting with Colón-Miranda and the Martinez-Matta brothers at the Las Villas apartments in Dorado. Hidal-go-Meléndez testified, “[El Gato] was just like bragging about the way he had killed Pacheco and explaining, like, he sewed with bullets the person of Pacheco.... ” In addition, El Gato told Hidalgo-Melén-dez that “Erick [Ortiz-Santiago] and his brother [Ortiz-Figueroa] had not been able to come downstairs from the building ... because one of the persons that had entered the project to kill the Rosario brothers were shooting at them.” B. The Murders of Ricardo Rivera-Dide and Samuel Serrano-Bermú-dez Wilfredo Martinez-Matta. began the next cacería with Santiago-Lugo by driving through the Bayamón area armed and looking for the Rosarios. After Colón-Miranda joined them, they found and followed Rivera-Dide and Serrano-Bermú-dez, known associates of the Rosarios. Wilfredo and Colón-Miranda shot. and killed both men as they sat in a car. Hi-dalgo-Meléndez testified that he later learned that Wilfredo had killed “Sammy” and Colón-Miranda had killed Sammy’s passenger. C. The Murders of Wilfredo Rivera-Rodríguez and Wilfredo Guzmán-Morales A third cacería occurred around Easter in 1994. At that time, Ibáñez-Maldonado, Colón-Miranda, and Martínez-Vélez met at the King’s Court mesa. There, they planned a cacería in search of the Rosarios “because of the drug point war.” They drove a stolen white van to look for the Rosarios. While driving, they came across two people on a motorcycle. They recognized someone they were looking for, and Colón-Miranda and someone else began shooting at the individuals on the motorcycle. Ibáñez-Maldonado testified that he had a Taurus 9mm firearm, Colón-Mi-randa had an AK-47 or an AR-15, and Martínez-Vélez had an M-14 that jammed. There were three other Taurus pistols in the van. After they shot the driver and the motorcycle crashed, Martínez-Vélez and Raúl Ortiz-Miranda exited the van and killed the victims. When a police scanner alerted them that the police were in pursuit, they fled to a mountainous area, abandoned the van, and hid some of the weapons under leaves. Ibáñez-Maldonado also testified that Martínez-Vélez had darker skin than Ortiz-Miranda and that Ortiz-Miranda was wearing a white cap. A police officer was following the white van as it pursued the motorcycle. After driving over the crest of a hill, the officer saw the bikers on the ground being shot by a tall, dark person and a tall, white person with a cap. A second officer responded to the shooting incident and chased the white van, which he eventually found near a hill. The police found several firearms near the van and a cap. Officers also seized casings for AR-15 and 9mm firearms within the van. VIII. The Murder of Rafael Cotto-Fuentes In 1994, Cotto-Fuentes was arrested for the murder of José Cruz-Rodríguez. He agreed to cooperate with authorities and was released on bond. At a meeting with Officer Rodriguez in late April or early May 1994, Cotto-Fuentes described the Santiago-Lugo drug organization. His testimony linked Colón-Miranda to the organization’s activities, including the Cruz-Rodríguez murder. Based on the information it received from CottoTFuentes, the Puerto Rico U.S. Attorney’s Office initiated an investigation. Cotto-Fuentes subsequently reported that Colón-Miranda, among others, had tried to kill him on May 20. Based on Cotto-Fuentes’ account of the attempted murder, a judge issued warrants for the arrest of Ortiz-Miranda, Co-lón-Miranda, and a co-conspirator. While Ortizh-Miranda was in custody, he and Co-lón-Miranda reviewed the complaint, and an officer heard Ortiz-Miranda comment that Cotto-Fuentes was a “snitch.” Cotto-Fuentes was murdered in June 1994. On July 27, 1994, Colón-Miranda was arrested. A forensics expert testified that the 9mm Taurus firearm seizéd from Colón-Miranda’s vehicle at the time of his arrest had an obliterated serial number; its barrel had been hollowed out to prevent identifying marking from forming on the bullet; and its firing pin had been filed down to disguise markings. However, the gun still produced identifying marks on the casing from the breach face, which is located at the rear of the gun, and these marks matched the twenty-four shell casings’ recovered from the murder scene. IX. The Arrests of Martínez-Vélez, Col-lazo-Aponte, and Merced-Morales On November 22, 1993, police officers stopped a stplen vehicle. The passengers fled, but the police arrested the driver, Martínez-Vélez, and seized a loaded “sub-machine gun,” two portable radios, and approximately $1,300 in currency. On September 29, 1994, a police officer observed Collazo-Aponte standing beside a car. The officer announced himself, and Collazo-Aponte threw a bag containing more than 1,000 decks of heroin into the car. He later stated that the ear was his. At the time Merced-Morales was arrested, law enforcement officers seized a scale, small ziplock bags, and additional drug paraphernalia from his residence as well as a list of high-powered firearms from his vehicle. DISCUSSION This case involves eight appellants, each raising a plethora of arguments. Not surprisingly, several arguments are raised by more than one appellant. Accordingly, in the interest of clarity, we have organized this opinion by issue and not by individual appellant. We begin with the arguments concerning pretrial motions and then proceed in a rough chronology through sentencing. I. Severance of the Cases of Ríos-Ríos, Collazo-Aponte, and Merced-Morales Severance motions made pursuant to Federal Rule of Criminal Procedure 14 are addressed to the sound discretion of the trial judge. This Court will interfere with the exercise of that discretion “only upon a demonstration of manifest abuse.” United States v. Boylan, 898 F.2d 280, 246 (1st Cir.1990); see also United States v. Cresta, 825 F.2d 538, 554 (1st Cir.1987); United States v. Talavera, 668 F.2d 625, 630 (1st Cir.1982). Accordingly, in order to prevail, appellants must “make a strong showing of prejudice.” Boylan, 898 F.2d at 246 (quoting United States v. Porter, 764 F.2d 1, 12 (1st Cir.1985)). In this context, “prejudice means more than just a better chance of acquittal at a separate trial.” United States v. Martinez, 479 F.2d 824, 828 (1st Cir.1973). As we have previously stated: This is a difficult battle for a defendant to win. There is always some prejudice in any trial where more than one offense or offender are tried together — but such “garden variety” prejudice, in and of itself, will not suffice. Even where large amounts of testimony are irrelevant to one defendant, or where one defendant’s involvement in an overall agreement is far less than the involvement of others, we have been reluctant to seeondguess severance denials. Boylan, 898 F.2d at 246 (citations omitted); see also Cresta, 825 F.2d at 554-55 (“[T]he fact that the defendant plays a minor role and that a substantial portion of the evidence is not directly related to the defendant, does not make it ‘automatically unlawful to try him with more important figures.’ ” (quoting United States v. Mahomud Rawwad, 807 F.2d 294, 295 (1st Cir.1986))). Here, Ríos-Ríos, Collazo-Aponte, and Merced-Morales contend that they suffered prejudicial spillover from the murder evidence presented in this case. We are well aware of the potential for prejudice in a complicated conspiracy trial involving several defendants. See, e.g., United States v. Smolar, 557 F.2d 13, 21 (1st Cir.1977); Gorin v. United States, 313 F.2d 641, 646 (1st Cir.1963). Nonetheless, in this case we see “little beyond the type and degree of prejudice customary in virtually all high-profile trials of multiple defendants and charges.” Boylan, 898 F.2d at 246. Here, as in Boylan, “[t]here is nothing to suggest that the number of defendants and charges was so large that the jury could not distinguish among them.” Id.; see also United States v. Luna, 585 F.2d 1, 5 (1st Cir.1978). Furthermore, the trial court gave appropriate limiting instructions as to the admissibility of evidence against particular defendants and as to the need to determine guilt on an individual basis. See United States v. Figueroa, 976 F.2d 1446, 1452 (1st Cir.1992) (“[E]ven assuming some evidentiary spillover, any prejudice was minimized by the limiting instructions given before and after the closing arguments.”); see also Boylan, 898 F.2d at 246; Smolar, 557 F.2d at 21. Under these circumstances, we hold that appellants have failed to “make a strong showing of prejudice.” Boylan, 898 F.2d at 246 (quoting Porter, 764 F.2d at 12). Accordingly, the district court did not abuse its discretion in denying appellants’ Rule 14 motion. II. The District Court’s Jury Screening Procedure On September 3, 1997, the trial judge stated that he intended to screen the jury outside the presence of the parties and counsel, as he did in the related case United States v. Candelarias-Silva, 166 F.3d 19, 31 (1st Cir.1999). There, the prospective jurors completed questionnaires and the judge excused those who lacked English proficiency, suffered from medical problems, or had previously scheduled travel plans. See id. at 29-31. On November 13, 1997, the judge screened the jury panel assigned to this case. Between September 3 and November 13, appellants did not object or request reconsideration of the court’s intention to screen the jury. However, on November 17, Rosario-Rodríguez and Ortiz-Figueroa did object and moved to quash the panel. The district court denied the motion. In Candelarias-Silva, we stated, “[i]f a judge does no more than what a jury clerk is authorized to do in excusing jurors, that may raise an issue of allocation of court resources but does not raise an issue of impropriety.” Id. at 31. Here, several appellants argue that the jury screening procedure violated their Fifth and Sixth Amendment rights, but they fail to provide the Court with any relevant citations to the record. In.fact, appellants do not even allege that the district court improperly dismissed jurors. Accordingly, we hold that Candelaria-Silva controls, and therefore appellants’ argument is without merit. See id. III. The District Court’s Decision to Empanel an Anonymous Jury Ríos-Ríos alleges that the decision to empanel an anonymous jury constituted an abuse of discretion. We disagree. A district court may empanel an anonymous jury when “the interests of justice so require.” 28 U.S.C. § 1863(b)(7). In this Circuit, we have held that an anonymous jury is “a permissible precaution where (1) there are strong grounds for concluding that it is necessary to enable the jury to perform its factfinding function, or to ensure juror protection; and (2) reasonable safeguards are adopted by the trial,court to minimize any risk of infringement upon the fundamental rights of the accused.” United States v. DeLuca, 137 F.3d 24, 31 (1st Cir.1998). Our review of this decision is not limited to “the evidence available at the time the anonymous empanelment occurred,” but may include “all relevant evidence introduced at trial.” Id. Here, the indictment charged several defendants with murder, all defendants with membership in a violent, sprawling drug conspiracy, and one defendant with intimidation and murder of a cooperating government witness. Under these circumstances, we hold that the record “affords sufficient foundation for empaneling an anonymous jury both as a prudent safety precaution and a means of ensuring unfettered performance of the factfinding function.” Id; see also United States v. Marrero-Ortiz, 160 F.3d 768, 776 (1st Cir.1998). Furthermore, the trial judge took adequate precautions to protect the defendants’ rights. As he had done in the related case of Marrero-Ortiz, the trial judge “did not mention any threat to juror safety, but, rather, informed' the jurors that they would remain anonymous during the trial because of publicity concerns. He then instructed the jury on the presumption of innocence, and 'periodically repeated that instruction as the trial progressed.” Marrero-Ortiz, 160 F.3d at 776. Under these circumstances, the trial judge did not exceed the scope of 'his discretion when he empaneled an anonymous jury in this case. IV. Restriction on Sidebar Participation During Voir Dire During voir dire, the trial judge restricted participation by defense counsel in sidebar conferences to “two of you at the most.” Although counsel for Ortiz-Figueroa suggested that ,all attorneys participate by using headphones, trial counsel for appellants did not object to the limitation. Ríos-Ríos now argues that the restrictions on sidebar participation during voir dire violated his right to be present at every critical stage of the trial. See Fed.R.Crim.P. 43(a). We disagree. This argument is controlled by United States v. Gagnon, 470 U.S. 522, 527, 105 S.Ct. 1482, 84 L.Ed.2d 486 (1985). There, the Supreme Court held: The mere occurrence of an ex parte conversation between a trial judge and a juror does not constitute a deprivation of any constitutional right. The defense has no constitutional right to be present at every interaction between a judge and a juror, nor is there a constitutional right to have a court reporter transcribe every such communication. Id. at 526, 105 S.Ct. 1482 (quoting Rushen v. Spain, 464 U.S. 114, 125-26, 104 S.Ct. 453, 78 L.Ed.2d 267 (1983) (Stevens, J., concurring)). In addition, the Court stated: If a defendant is entitled under Rule 43 to attend certain “stages of the trial” which do not take place in open court, the defendant or his counsel must assert that right at the time; they may not claim it for the first time on appeal from a sentence entered on a jury’s verdict of “guilty.” Id. at 529, 105 S.Ct. 1482. In this case, Ríos-Ríos was restricted from full participation in a limited number of sidebar conferences that occurred during voir dire; in all other aspects, appellant was present at, and fully participated in, his trial. In addition, trial counsel did not object to the restriction, and counsel subsequently exercised cause and peremptory challenges without objecting that there was not enough information to make those decisions. On these facts, we see no Rule 43 violation. V. The Defense’s Request to Use the Government’s Witness List During Voir Dire Ríos-Ríos alleges that the trial court abused its discretion in refusing the defense’s request for disclosure of the prosecution’s witnesses during voir dire. This argument is meritless. In this Circuit, the law is settled: “[T]here is no constitutional or statutory requirement that the identity of prosecution witnesses be disclosed before trial.” United States v. Bello-Pérez, 977 F.2d.664, 670 (1st Cir.1992); see also United States v. Reis, 788 F.2d 54, 58 (1st Cir.1986); United States v. Barrett, 766 F.2d 609, 617 (1st Cir.1986). VI. Juror 58’s Previous Service in an Unrelated Trial Ríos-Ríos also argues that Juror 58’s previous service in an unrelated trial involving government witness Ibáñez-Mal-donado resulted in bias. We see no merit in this argument. During Ibáñez^-Maldo-nado’s testimony, Juror 58 informed the trial judge of his service in a previous trial that ended in an acquittal of Ibáñez^-Mal-donado. The judge then conducted voir dire outside the presence of the jury. Juror 58 stated that he could serve impartially in this case and, although he had mentioned his prior service to his fellow jurors, he had not discussed the details of the case. Upon further inquiry, the court determined that the prior case involved a drug charge unrelated to the Santiago-Lugo organization. Exercising an abundance of caution, the trial judge queried the defense; defense counsel informed the court that they did not want Juror 58 dismissed. The judge recalled the jurors and instructed them that Juror 58 had served in a previous case in which Ibáñez-Maldonado was accused, but that Juror 58 could participate in the present case. The judge emphasized that Juror 58 should not discuss the previous case with the jurors and that Juror 58 had to disregard the previous case in considering the present one. We conclude that the trial judge’s careful voir dire of Juror 58 was sufficient to assess his impartiality and the potential taint of the entire panel. Further, the judge carefully instructed the jury to disregard the juror’s prior service. As we have previously held, “the trial judge is vested with the discretion to fashion an appropriate and responsible procedure to determine whether misconduct actually occurred and whether it was prejudicial.” United States v. Ortiz-Arrigoitia, 996 F.2d 436, 443 (1st Cir.1993); see also Boylan, 898 F.2d at 258. Therefore, appellant’s claim of bias fails. VII. Statements Made by Co-Conspirator “El Gato” to Hidalgo-Melén-dez Ortiz-Figueroa alleges that certain statements indicating his participation in the April 19, 1993 cacería that resulted in the murder of Pacheco-Aponte were inadmissible hearsay. The trial court admitted the statements pursuant to Fed. R.Evid. 801(d)(2)(E). This Court reviews that decision for plain error. See United States v. McCarthy, 961 F.2d 972, 977 (1st Cir.1992). Hearsay statements are inadmissible as a matter of law. See Fed. R.Evid. 801(c). However, pursuant to Rule 801(d)(2)(E), “a statement by a cocon-spirator of a party during the course and in furtherance of the conspiracy” is not hearsay. To invoke this evidentiary exception, the movant “must show by a preponderance of the evidence that a conspiracy embracing both the declarant and the defendant existed, and that the declarant uttered the statement during and in furtherance of the conspiracy.” United States v. Sepúlveda, 15 F.3d 1161, 1180 (1st Cir.1993); see also Bourjaily v. United States, 483 U.S. 171, 175-76, 107 S.Ct. 2775, 97 L.Ed.2d 144 (1987). In other words, the trial court must conclude that (1) “it is more likely than not that the declarant and the defendant were members of a conspiracy when the hearsay statement was made,” and (2) that “the statement was in furtherance of the conspiracy.” United States v. McCarthy, 961 F.2d 972, 977 (1st Cir.1992) (quoting United States v. Petrozziello, 548 F.2d 20, 23 (1st Cir.1977)). In this case, several of the co-conspirators met at the Las Villas apartments in Dorado following the April 19, 1993 cacería. At that meeting, El Gato made several incriminating statements. Hidalgo-Meléndez testified that El Gato was “just like bragging about the way he had killed Pacheco and explaining, like, he sewed with bullets the person of Pacheco.” El Gato also told Hidalgo-Meléndez that “Erick [Ortiz-Santiago] and his brother [Ortiz-Figueroa] had not been able to come downstairs from the building ... because one of the persons that had entered the project to kill the Rosario brothers were shooting at them.” The district court concluded that these statements were admissible pursuant to Fed.R.Evid. 801(d)(2)(E). We agree. First, the record contains ample evidence that (1) the cacerías were conducted in furtherance of the drug conspiracy, and (2) the declarant and Ortiz-Figueroa were members of that conspiracy when the hearsay statements were made. Second, El Gato’s information confirmed for Hidal-go-Meléndez what had transpired within the organization, who had participated in the cacería, and “the people that [he ran] a risk with.” As we have previously stated, “the reporting of significant events by one coconspirator to another advances the' conspiracy.” Sepulveda, 15 F.3d at 1180. Accordingly, El Gato’s statements were properly admitted into evidence. Alternatively, we hold that any error in admitting El Gato’s statements was harmless. Ortiz-Figueroa was arrested as he fled the murder scene at Davila. At the time of his arrest, police seized a plethora of incriminating evidence, including a bag containing firearms and ammunition, a rock of heroin or cocaine, a cellular telephone, a glove, two masks, and a firearm he was carrying on his person. Further, the record also contains co-conspirator and police testimony indicating Ortiz-Figueroa’s participation in the cacería. Accordingly, we conclude that the outcome of the trial would have been the same regardless of whether El Gato’s statements were admitted. VIII. Evidence Regarding Collazo-Aponte, Ortiz-Figueroa, and Ortiz-Santiago’s Income Taxes Appellants allege that the district court erroneously admitted income tax certificates for Collazo-Aponte, Ortiz-Figueroa, and Ortiz-Santiago. In support of their argument, appellants cite Fed. R.Evid. 401, 403, and 404(b). At trial, the prosecution argued that the absence of tax returns demonstrated the absence of legitimate income and, therefore, a motive for engaging in the drug conspiracy. The trial court agreed, ruling (1) the tax returns were relevant to determine if a defendant alleged to have drug trafficking income declared any legitimate income, and (2) the tax certificates did not concern the crime of failing to file tax returns. We review the district court’s evidentiary rulings for abuse of discretion. See United States v. Houlihan, 92 F.3d 1271, 1297 (1st Cir.1996); United States v. Rivera-Gomez; 67 F.3d 993, 997 (1st Cir.1995). Even if the trial court did err by admitting the tax certificates, we nonetheless conclude that, given the overwhelming proof of appellants’ participation in' the drug conspiracy, any error was harmless. See United States v. Sabatino, 943 F.2d 94, 98 (1st Cir.1991); United States v. Rodriguez-Cardona, 924 F.2d 1148, 1152 (1st Cir.1991). We therefore reject this argument without further discussion. IX. The Search of Merced-Morales’ Residence Merced-Morales alleges that the trial court should have suppressed the evidence seized from his residence and vehicle because the arresting officers (1) did not knock and announce their presence before breaking the gate padlock, (2) entered his home after arresting him outside, and (3) obtained his consent to search under duress. Appellant’s arguments are without merit. The trial court conducted a mid-trial suppression hearing. At that time, the following evidence was presented. Merced-Morales was arrested by a team of law enforcement officers led by DEA Special Agent German Blanco. Agent Blanco testified that his officers took extra precautions when executing the arrest warrant for Merced-Morales due to the violent nature of the organization. Specifically, the agents broke the padlock on the driveway entrance gate and entered the driveway without announcing their presence. According to Agent Blanco, he believed this was necessary (1) to reduce the risk of a surprise attack by whoever might be in the house and (2) to reduce the likelihood that anyone in the house could flee. After the officers proceeded to safer positions near the main entrance and the sides of the house, Agent Blanco began knocking on the main entrance gate and announced his presence. When Merced-Morales came down the stairs inside the house, Agent Blanco ordered him to open the gate and the wooden door behind it. When Merced-Morales opened the door, the police team entered his residence and initiated a protective sweep. Contemporaneously, Agent Blanco advised Merced-Morales of his constitutional rights in Spanish, using DEA Form 13A. According to Agent Blanco’s testimony, Merced-Mor-ales stated that he understood his rights. Agent Blanco further testified that there were no guns aimed at Merced-Morales, the officers did not threaten him, and he did not appear to be under the influence of drugs or alcohol. Merced-Morales then verbally consented to a search of his residence, and he signed a written consent form in Spanish after both he read it and Agent Blanco read it to him. The officers then seized a revolver, drug paraphernalia, marijuana, and a list of firearms. The defense presented contrary testimony. Merced-Morales’ sister testified that the lock on the wooden front door was broken and there was damage to the door jamb following the arrest. She added that Merced-Morales had told her that the police entered the house by forcing open the front door. Merced-Morales testified that he was awakened by police pounding on his door. When he approached the door, police aimed a rifle at him through an open window, ordered him not to move, and then broke in through the door. Merced-Morales alleged he was then forced to sign a consent form at gunpoint and was informed that the searches would proceed even if he refused to sign. He further stated that as police officers escorted him out of the house, he saw that the doorlock and the edge of the door were broken. On cross-examination, Merced-Morales testified that he had seen a crow bar and a sledgehammer only as officers returned them to a police vehicle and that the door showed no marks from a sledgehammer. After hearing all of the evidence, the district court ruled that (1) the agents lawfully broke the padlock on the driveway gate due to exigent circumstances, namely the organization’s known violence, (2) agents announced their presence as soon as their safety was less compromised, and (3) Merced-Morales opened his door with no breaking or entering by police. While this Court reviews factual determinations supporting the' denial of suppression motions for clear error, see United States v. Twomey, 884 F.2d 46, 51-52 (1st Cir.1989), we review de novo whether exigent circumstances justify entry without notice, cf. United States v. Tibolt, 72 F.3d .965, 969 (1st Cir.1995) (“[Wjhether a particular set of circumstances gave rise to ... ‘exigent circumstances’ is reviewed de novo and findings of fact are reviewed for clear error.”); United States v. Gooch, 6 F.3d 673, 679 (9th Cir.1993) (‘We review de novo whether exigent circumstances justify a warrant-less arrest or seizure.”); United States v. Echegoyen, 799 F.2d 1271, 1277-78 (9th Cir.1986) (“The ultimate issue of whether exigent circumstances justify a warrantless entry and/or search is resolved under the de novo standard.”). “Where, as here, there are no explicit factual findings, the record below is assessed in the light most favorable to the trial court ruling.” Tibolt, 72 F.3d at 969. First, we reject Merced-Mor-ales’ argument that the search of his residence and automobile was unlawful in light of the agents’ failure to knock and announce. The Supreme Court has held: [F]or Fourth Amendment purposes, an arrest warrant founded on probable cause implicitly carries with it the limited authority to enter a dwelling in which the suspect lives when there is reason to believe the suspect is within. Payton v. New York, 445 U.S. 573, 603, 100 S.Ct. 1371, 63 L.Ed.2d 639 (1980); see also Steagald v. United States, 451 U.S. 204, 214 n. 7, 221, 101 S.Ct. 1642, 68 L.Ed.2d 38 (1981) (“Because an arrest warrant authorizes the police to deprive a person of his liberty, it necessarily also authorizes a limited invasion of that person’s privacy interest when it is necessary to arrest him in his home.”). As a general rule, officers must give notice of their authority and purpose before entering private premises to make an arrest. See Wilson v. Arkansas, 514 U.S. 927, 930, 115 S.Ct. 1914, 131 L.Ed.2d 976 (1995) (holding common law knock-and-announce principle forms part of the Fourth Amendment reasonableness inquiry). However, the so-called knock-and-announce rule is not without its exceptions. Specifically, entry without notice to execute an arrest warrant is permissible when notice would jeopardize the safety of the officers. See Ker v. California, 374 U.S. 23, 39-40, 83 S.Ct. 1623, 10 L.Ed.2d 726 (1963) (holding Fourth Amendment not violated by failure to announce where compliance would have increased officer’s peril); cf. Fletcher v. Town of Clinton, 196 F.3d 41, 49 (1st Cir.1999) (“[T]hreat to police or the public safety is sufficient to create exigent circumstances.” (internal quotation omitted)). In addition, we note that- “the Supreme Court’s standard of reasonableness [for Fourth Amendment purposes] is comparatively generous to the police in cases where potential danger, emergency conditions or other exigent circumstances are present.” Roy v. Inhabitants of Lewiston, 42 F.3d 691, 695 (1st Cir.1994). Accordingly, Agent Blanco and his officers had a right to enter Merced-Morales’ residence in order to execute the warrant for his arrest. See Payton, 445 U.S. at 602-03, 100 S.Ct. 1371; Steagald, 451 U.S. at 214 n. 7, 221, 101 S.Ct. 1642. Further, the officers knocked and announced their presence once they had obtained safe positions near the main entrance and the sides of the house. If the officers had announced their presence prior to entering the driveway gate, the officers would have been exposed to any threat emanating from the house. The record contains ample evidence that, the officers, knew Merced-Morales was a member of a well-armed and extremely violent drug organization. Under these circumstances, we hold that the authorities’ failure to knock and announce prior to breaking the padlock on the driveway entrance gate was justified by exigent circumstances. See Ker, 374 U.S. at 39-40, 83 S.Ct. 1623; see also Tibolt, 72 F.3d at 969 (stating exigent circumstances include situations posing a threat to police). Next, we turn to Merced-Morales’ contention that the police arrested him outside of1 his house. This version of events is contrary to Merced-Morales’ testimony before the district court that the police broke down his door. Accordingly, this argument has been waived. “A litigant cannot jump from theory to theory like a bee buzzing from flower to flower. To the precise contrary, when a party fails to raise a theory at the district court level, that theory is generally regarded as forfeited and cannot be advanced on appeal.” United States v. Torres, 162 F.3d 6, 11 (1st Cir.1998); see also United States v. Slade, 980 F.2d 27, 30 (1st Cir.1992) (“It is a bedrock rule that when a party has not presented an argument to the district court, she may not unveil it in the court of appeals.”). Finally, we affirm the district court’s finding th^t the search of Merced-Morales’ residence and'vehicle was consensual. The voluntariness of consent is a question of fact determined by the totality of the circumstances. See United States v. Mendenhall, 446 U.S. 544, 557, 100 S.Ct. 1870, 64 L.Ed.2d 497 (1980); Schneckloth v. Bustamonte, 412 U.S. 218, 226, 227, 93 S.Ct. 2041, 36 L.Ed.2d 854 (1973); United States v. Barnett, 989 F.2d 546, 554 (1st Cir.1993). Among other factors, a district court must consider “whether the consenting party was advised of his or her constitutional rights and whether permission to search was obtained by coercive means or under inherently coercive circumstances.” Barnett, 989 F.2d at 555; see also Schneckloth, 412 U.S. at 226, 93 S.Ct. 2041; United States v. Twomey, 884 F.2d 46, 51-52 (1st Cir.1989). “Although sensitivity to the heightened possibility of coercion is appropriate when a defendant’s consent is obtained during custody, see Schneckloth, 412 U.S. at 240, n. 29, 93 S.Ct. 2041, ‘custody alone has never been enough in itself to demonstrate ... coerced ... consent to search.’ ” Barnett, 989 F.2d at 555 (quoting United States v. Watson, 423 U.S. 411, 424, 96 S.Ct. 820, 46 L.Ed.2d 598 (1976)). Here, Agent Blanco’s testimony contradicted Merced-Morales’ allegation of being coerced and held at gunpoint. The trial court observed both witnesses and determined that Agent Blanco’s testimony was more credible. Where, as here, “there are two competing interpretations of the evidence, the district court’s choice of one of them cannot be clearly erroneous.” United States v. Cruz Jiménez, 894 F.2d 1, 7 (1st Cir.1990); see also United States v. Zapata, 18 F.3d 971, 974 (1st Cir.1994) (holding trial judge’s denial of a suppression motion is entitled to considerable deference because he had opportunity to hear testimony, observe witness demeanor, and evaluate facts first hand). Accordingly, we conclude that appellant’s arguments on this issue are without merit. X. Evidence Seized at the Time of Merced-Morales ’ Arrest Merced-Morales argues that the evidence seized at the time of his arrest should have been suppressed because: (1) the drug conspiracy ended in 1995 when certain members of the Santiago-Lugo organization were arrested, and therefore the evidence was inadmissable pursuant to Fed.R.Evid. 404(b); and (2) the risk of undue prejudice outweighed the probative value of the evidence pursuant to Fed. R.Evid. 403. We review for abuse of discretion. See Houlihan, 92 F.3d at 1297; Rivera-Gómez, 67 F.3d at 997. Finding no error, we affirm the ruling of the district court. There is no evidence in the record that the drug conspiracy involved in this ease ended prior to the arrest of Merced-Morales. The law on this question is settled: “Where a conspiracy contemplates a continuity of purpose and a continued performance of acts, it is presumed to exist until there has been an affirmative showing that it has terminated.” E.g., United States v. Elwell, 984 F.2d 1289, 1293 (1st Cir.1993). Contrary to appellant’s assertion, the arrest of some co-conspirators does not automatically terminate a conspiracy. See, e.g., United States v. Mealy, 851 F.2d 890, 901 (7th Cir.1988) (“A co-conspirator’s arrest does not automatically terminate a conspiracy; the remaining conspirators may continue to carry out the goals of the conspiracy notwithstanding the arrest of one of their partners.”); United States v. Thompson, 533 F.2d 1006, 1010 (6th Cir.1976) (same). In addition, there is no evidence in the record that Merced-Morales withdrew from the conspiracy prior to his arrest. “To withdraw, a conspirator must take some affirmative action ‘either to defeat or disavow the purposes of the conspiracy.’ ” United States v. Muñoz, 36 F.3d 1229, 1234 (1st Cir.1994) (quoting United States v. Juodakis, 834 F.2d 1099, 1102 (1st Cir.1987)). Since the record does not indicate that Merced-Morales withdrew from the drug conspiracy, and since the drug paraphernalia and firearms list were consistent with his involvement in the conspiracy, the trial court did not err by admitting these items into evidence. XI. Withdrawal of the Firearm Seized From Merced-Morales’ Vehicle Merced-Morales argues that the trial court erred when it denied his motion for a mistrial. Merced-Morales moved for a mistrial when the court withdrew from evidence a revolver seized from his vehicle at the time of his arrest. We review a trial court’s refusal to grant a mistrial for abuse of discretion; absent a clear showing of prejudice, we will uphold the lower court’s ruling. See United States v. Zanghi, II, 189 F.3d 71, 82 (1st Cir.1999); United States v. Gomes, 177 F.3d 76, 82 (1st Cir.1999). We briefly review the facts relevant to this argument. The police arrested Merced-Morales at his residence. After the authorities had properly informed him of his constitutional rights, Merced-Mor-ales consented to a search of his house and vehicle. Pursuant to this search, the police seized a revolver. At trial, the court initially admitted the weapon into evidence. However, at the close of the prosecution’s case, the trial judge requested additional information. At that time, the prosecution requested that the firearm be withdrawn from evidence. The court agreed, and the trial judge reversed his prior admissibility ruling. Merced-Mor-ales then moved for a mistrial, but the court denied the motion. Before Merced-Morales’ trial counsel began his deferred opening statement, the judge instructed the jury that rulings on the admissibility of evidence could change during the course of trial and that the jury could not consider excluded evidence. With respect to the revolver, the judge stated: [T]he gun will not be in evidence any further, since I have now found that the possession of this particular revolver is too remote in time to the conspiracy as to be related to the conspiracy.... [Y]ou cannot consider this gun as evidence, and I instruct you to disregard that particular revolver that was seized in his car at the time of his arrest. We have previously stated that “[t]rials are expected to be fair, but not necessarily perfect; and appeals courts are slow to insist on mistrials, even in cases where [improper evidence] may actually convey prejudicial information.” Gomes, 177 F.3d at 82. Where, as here, “a curative instruction is promptly given, a mistrial is warranted only in rare circumstances implying extreme prejudice.” United States v. Torres, 162 F.3d 6, 12 (1st Cir.1998); see also United States v. Magana, 127 F.3d 1, 6 (1st Cir.1997) (“Jurors are' presumed to follow [curative] instructions, except in extreme cases.”). Here, the judge instructed the jury on the inadmissibility of the revolver prior to the deferred opening statement of counsel for Merced-Morales. This allowed the jury to connect the judge’s revised ruling on this one piece of evidence directly with Merced-Morales. The revolver, moreover, has little significance: the record contains ample evidence of appellant’s guilt, including the testimony of two cooperating eyewitnesses. See Rivera-Gómez, 67 F.3d at 999 (“[T]he strength of the government’s overall case is frequently a cardinal factor in evaluating the denial of a mistrial motion.”). Under these circumstances, we conclude that Merced-Morales has not demonstrated extreme prejudice, and therefore this argument fails. See Torres, 162 F.3d at 12. XII. Delayed Disclosure that a Government Witness Failed to Identify Ríos-Ríos in a Pre-Trial Photograph Array Ríos-Ríos alleges that the district court should have sanctioned the prosecution for failing to timely disclose that Hidalgo-Meléndez failed to identify Ríos-Ríos in a pretrial photograph array. A district court’s decision on how to handle delayed disclosure of Brady material is reviewed for abuse of discretion. See United States v. Catano, 65 F.3d 219, 227 (1st Cir.1995). Prosecutors have an obligation to furnish exculpatory and impeachment information to the defense in a timely fashion. See Brady v. Maryland, 373 U.S. 83, 87, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963). Where the defense is confronted not with complete suppression, but rather with delayed disclosure, “the test is whether defendant’s counsel was prevented by the delay from using the disclosed material effectively in preparing and presenting the defendant’s case.” United States v. Ingraldi, 793 F.2d 408, 411-12 (1st Cir.1986); see also Catano, 65 F.3d at 227. In United States v. Ayres, 725 F.2d 806, 811 (1st Cir.1984), we held that there was no prejudice when disclosure of a failed photograph identification attempt, although delayed, was sufficiently timely for cross-examination of the witness. Here, Hídalgo-Meléndez testified that Ríos-Ríos was someone who once delivered cocaine to Santiago-Lugo. The day after this testimony was given, the prosecution belatedly disclosed that Hidalgo-Meléndez had failed to identify Ríos-Ríos in a pretrial photo array. The judge concluded that although the government should have informed Ríos-Ríos at the time of the in-court identification, it would not preclude the government from eliciting the information during Hidalgo-Melén-dez’s direct examination. Thereafter, the failed identification attempt was introduced first by the prosecution on direct examination, and then again by defense counsel on cross-examination. In addition, the judge instructed the jury that (1) a prior failure to identify was relevant to a witness’ credibility, and (2) the prosecution had the burden of proving the identity of the defendant. Under these circumstances, we conclude that Ríos-Ríos cannot show prejudice from the delayed disclosure. Therefore, this argument fails. See, e.g., Ayres, 725 F.2d at 811. XIII. The Prosecution’s Failure to Turn Over the Sworn Statement of Officer Burgos Ríos-Ríos alleges that the district court erred in concluding that the prosecution had no obligation to turn over the sworn statement of Officer Burgos. The district court ruled that Officer Burgos’ sworn statement regarding Ortiz-Santiago’s arrest was not discoverable as Jencks Act material, see 18 U.S.C. § 3500, since the government could not obtain it from the Commonwealth of Puerto Rico office that had created and maintained it. We see no error in this determination. See, e.g., United States v. Durham, 941 F.2d 858, 861 (9th Cir.1991) (“Under the Jencks Act, the prosecutor is required to disclose only those statements which are in the possession of the United States.”); United States v. Polizzi, 801 F.2d 1543 (9th Cir.1986) (same). XIY. Cooperating Witness Instruction A. Merced-Morales ’ Argument Merced-Morales argues that the trial judge’s decision not to use his proposed jury instruction regarding the cooperating witnesses Ibáñez-Maldonado, Ramos-Rodríguez, and Hidalgo-Meléndez violated his right to a fair trial and due process of law. The instruction proposed by Merced-Morales stated: It is inappropriate to hold a defendant in prison for long periods of time pending sentencing while the government extracts information from him [because] this practice increases the likelihood that innocent individuals will be implicated by defendant tryin