United States Court of Appeals

FOR THE DISTRICT OF COLUMBIA CIRCUIT

Argued April 10, 2018 Decided August 17, 2018

No. 15-3040

UNITED STATES OF AMERICA,

APPELLEE

v.

NOE MACHADO-ERAZO, ALSO KNOWN AS GALLO, ALSO 

KNOWN AS NOE MARCHADO-ERAZO,

APPELLANT

Consolidated with 15-3041, 15-3043

Appeals from the United States District Court

for the District of Columbia

(No. 1:10-cr-00256-8)

(No. 1:10-cr-00256-9)

(No. 1:10-cr-00256-20)

Kira Anne West, Christine Pembroke, Marc Eisenstein, 

and Thomas G. Corcoran Jr., all appointed by the court, argued 

the causes for Appellants. With them on the joint briefs was 

Barry Coburn, appointed by the court.

Elizabeth Gabriel, Assistant U.S. Attorney, U.S. 

Attorney’s Office, argued the cause for Appellee. With her on 
2

the brief were Jessie K. Liu, U.S. Attorney, and Elizabeth 

Trosman and John P. Mannarino, Assistant U.S. Attorneys.

Before: ROGERS, WILKINS and KATSAS, Circuit Judges.

Opinion for the Court filed by Circuit Judge WILKINS.

Concurring opinion filed by Circuit Judge ROGERS.

WILKINS, Circuit Judge: Appellants – Yester Ayala (aka 

“Freeway” or “Daddy Yankee”), Noe Machado-Erazo (aka 

“Gallo”), and Jose Martinez-Amaya (aka “Crimen” or 

“Mecri”) – were charged with conspiracy to violate the 

Racketeer Influenced and Corrupt Organizations (“RICO”)

statute, in violation of 18 U.S.C. § 1962(d), and various other 

crimes. After a three-week trial, the jury returned guilty 

verdicts as to all three Appellants. 

The District Court sentenced Machado-Erazo and 

Martinez-Amaya to concurrent terms of life imprisonment for 

RICO conspiracy and murder in aid of racketeering, and to 10 

years’ consecutive imprisonment for possession of a firearm 

during and in relation to a crime of violence. Ayala was 

sentenced to concurrent terms of imprisonment for 20 years for 

RICO conspiracy and 30 years each for the remaining counts, 

and concurrent terms of five years of supervised release for 

each D.C. murder count. 

Appellants now challenge their convictions and sentences 

on various grounds. Because we find none of Appellants’ 

challenges persuasive, we affirm. 
3

I.

A. 

According to the evidence presented at trial, Appellants 

were members of MS-13, a transnational gang founded in El 

Salvador. At the time, MS-13 used a hierarchical structure. 

The principal leaders of the gang, known as “la Ranflas,” are 

located in El Salvador. The second level of the hierarchy, 

“programs,” function as collections of the lowest rung of the 

hierarchy, local “suborganization[s]” or “cell[s]” known as 

“cliques.” While Appellants were involved with MS-13, the 

cliques convened regular meetings at which members paid 

dues and discussed clique activities. The cliques also obtained 

funding by collecting “taxes” (“renta”) from certain entities 

within their respective territories. Each clique had two leaders, 

the primary leader, who had the “first word” (“primera 

palabra”), and the secondary leader, who had the “second 

word” (“segunda palabra”). Within a clique, MS-13 members 

were assigned specific roles, including “recruiter,” 

“extortionist,” “keep[er] [of] weapons,” and treasurer. Groups 

of cliques comprised “programs,” which were run by the 

gang’s leadership in El Salvador (the “Ranfla”). 

Members of MS-13 marked their territory with graffiti, 

used hand signals to identify themselves, and tattooed their 

bodies with gang symbols. Gang members were expected to 

abide by strictly enforced “rules” that mandated attendance at 

regularly scheduled clique meetings, the payment of dues, the 

refusal to cooperate with law enforcement, and the murder of 

rival gang members (“chavalas”). Members who failed to 

follow these rules were subjected to physical punishment or 

death. MS-13’s leaders authorized the killing of a recalcitrant 

member by issuing a “green light,” which other gang members 
4

were expected to execute when possible or face punishment or 

death themselves. 

At trial, the Government presented evidence that 

Machado-Erazo and Martinez-Amaya were members of the 

Normandie clique in the D.C. area, and that both had leadership 

roles. Machado-Erazo helped financially support the clique 

through drug dealing and the extortion of local brothels and 

other drug dealers. Moises Humberto Rivera-Luna (aka “Viejo 

Santos”), who oversaw MS-13’s activities in the Washington,

D.C. area despite being incarcerated in El Salvador, called on 

Machado-Erazo to “improve the [Normandie] clique.” J.A. 

1603-04. Machado-Erazo worked with one of the clique’s

leaders, Jorge Solorzano, to achieve this goal. Machado-Erazo 

was also one of the leaders of “La Hermandad,” a program of 

local cliques with the purpose of “clean[ing] up the cliques” by 

“kill[ing] . . . the snitches.” J.A. 1395, 1617-18, 1739. 

Martinez-Amaya was sent from El Salvador to assist the 

Normandie clique when Dennis Gil-Bernardez (aka “Pando”), 

its longtime leader, was arrested in December 2008. J.A. 1082

(stating that Pando was arrested in December 2008), 1244 

(stating that Martinez-Amaya (aka “Crimen”) was sent to D.C. 

after Pando was arrested). Martinez-Amaya served as 

second-in-command to Solorzano, and when Solorzano was 

arrested, Martinez-Amaya became the clique leader. 

The Government separately presented evidence that Ayala 

was a member of the Sailors clique, another clique in the D.C. 

area, and was one of its leaders in 2008. 

 

B. 

By superseding indictment filed on May 9, 2013, 

Appellants and four co-conspirators were charged with 
5

conspiracy to violate the RICO statute, in violation of 18 

U.S.C. § 1962(d). Ayala was also charged with two counts of 

murder in aid of racketeering (“VICAR murder”), in violation 

of 18 U.S.C. § 1959(a)(1), and two counts of first-degree 

murder while armed, in violation of D.C. Code §§ 22-2101 and 

22-4502. In addition to the RICO conspiracy charge, 

Machado-Erazo and Martinez-Amaya were charged with one 

count each of VICAR murder and possession of a firearm 

during and in relation to a crime of violence, in violation of 18 

U.S.C. § 924(c)(1)(A).

Appellants’ trial lasted from June 18, 2013, to August 6, 

2013. Presentation of evidence lasted approximately fourteen 

court days, and the jury deliberated for eleven days. The 

parties called approximately fifty witnesses and introduced 

over two hundred exhibits. United States v. Machado-Erazo, 986 

F. Supp. 2d 39, 43 (D.D.C. 2013). Among the government’s 

evidence were testimony of co-conspirators regarding MS-13 

activities in the D.C. area, consensual recordings of MS-13 

meetings, and wiretaps of calls among MS-13 members, 

including the three defendants. Id. 

The jury returned verdicts of guilty as to all three 

defendants. Machado-Erazo and Martinez-Amaya were found 

guilty of (1) violating RICO, (2) VICAR murder, and (3) 

possession of a firearm during and in relation to a crime of 

violence. The jury answered the special finding in the 

affirmative, determining that both defendants “did feloniously, 

willfully, and of deliberately premeditated malice aforethought 

kill and murder Felipe Leonardo Enriquez.” J.A. 709, 711. 

The jury also found that the pattern of racketeering activity 

agreed to included (i) murder in violation of the D.C. Code or 

Maryland law; (ii) extortion in violation of the D.C. Code or 

Maryland law; and (iii) obstruction of justice. The jury found, 

however, that the pattern of racketeering activity did not 
6

include robbery, violation of federal narcotics laws, or witness 

retaliation or tampering. J.A. 708-09, 710-11.

Ayala was also convicted of participating in the same 

RICO conspiracy. The jury found that Ayala agreed to the 

same three racketeering activities, and returned guilty verdicts 

against Ayala as to two counts of VICAR murder and two 

counts of murder under the D.C. Code deriving from the 

killings of Luis Alberto Membreno-Zelaya on or about 

November 6, 2008, and of Giovanni Sanchez on or about 

December 12, 2008. J.A. 712-15.

After the jury rendered its verdict, Machado-Erazo and 

Martinez-Amaya filed timely renewed motions for judgment of 

acquittal and for a new trial based on the insufficiency of the 

evidence, as well as on other grounds not relevant here. The 

District Court denied both motions. See Machado-Erazo, 986 

F. Supp. 2d at 57. Subsequently, the District Court sentenced 

Machado-Erazo and Martinez-Amaya to concurrent terms of 

life imprisonment for RICO conspiracy and VICAR murder, 

and to 10 years’ consecutive imprisonment for possession of a 

firearm during and in relation to a crime of violence. The court 

sentenced Ayala to concurrent terms of imprisonment for 20 

years for RICO conspiracy and 30 years each for the remaining 

counts, and concurrent terms of five years of supervised release 

for each D.C. murder count. 

Appellants now challenge their convictions and sentences 

on various grounds. We consider Appellants’ claims that other 

crimes evidence was improperly admitted in part II, their 

claims that cell-site data was improperly admitted in part III, 

and their other claims in an unpublished judgment issued 

herewith. 
7

II.

Appellants challenge the admission under Federal Rules

of Evidence 404(b) and 403 of the following acts of violence 

perpetrated by co-conspirators: (1) the July 29, 2008, murder 

of Luis Chavez-Ponce by Gil-Bernardez; (2) the October 6, 

2008, shooting of Malcom Wilson, David Cook, and Dalton 

Beck by Gill-Bernardez; (3) August and September 2008 

shootings in Sterling, Virginia; (4) the October 16, 2009, armed 

gang fight in Wheaton, Maryland; and (5) the December 9, 

2009, shooting of Glorisnel Sorto by Mario Lopez-Ramirez. 

Appellants argue that the Government did not tie this 

evidence to Appellants, and as such, the testimony with respect 

to these incidents, as well as photographs of the crime scenes,

were not relevant and were unduly prejudicial. Appellants’ Br. 

36-37. Appellants assert that the “evidence was nothing more 

than evidence of bad character, or guilt by association, intended 

to sway the jury,” and make the jury believe “that appellants 

would likely have committed the acts . . . alleged[.]” Id. at 37. 

The Government, however, argues that admitting this evidence 

was not in error because these crimes, some of which were 

charged as overt acts, were direct proof of the conspiracy, and 

thus were not subject to exclusion under Federal Rule of 

Evidence 404(b). Appellee’s Br. 26-27. The Government has 

the stronger position here, and we hold that the District Court 

did not abuse its discretion in allowing this evidence.

A.

Below is a summary of the challenged evidence.

1

 None of 

the three Appellants was present during any of these incidents, 

 

1

In reply, Appellants suggest that they object to the admission of 

additional evidence not specified in their opening brief. Reply 2. 
8

but each of the incidents involved members of the Normandie 

clique, of which Machado-Erazo and Martinez-Amaya were 

members. And, as discussed further below, the evidence 

showed a close connection between the Normandie clique and 

the Sailors clique, of which Ayala was a member. 

Murder of Luis Chavez-Ponce. At trial, co-conspirator 

Antonio Urrutia-Barrera, a member of the Normandie clique, 

testified that he was with Tokiro Rodas-Ramirez, 

Gil-Bernardez, then clique leader, and other members of the 

clique at an apartment complex in Riverdale, Maryland on July 

29, 2008, when they spotted Chavez-Ponce, a rival gang 

member, riding a bicycle around the complex. J.A. 1227-29, 

1342; Appellee’s Br. 20-21. According to Urrutia-Barrera, 

Gil-Bernardez shot Chavez-Ponce. J.A. 1229.

Shootings of Malcom Wilson, David Cook, and Dalton 

Beck. Urrutia-Barrera also testified to the shooting of Wilson, 

Cook, and Beck that occurred in October 2008. According to 

Urrutia-Barrera, he, Gil-Bernardez, and other members of the 

Normandie clique were in a car in Reston, Virginia, when they 

saw rival gang members Wilson, Cook, and Beck in another 

car flashing gang signs. J.A. 1238-39; Appellee’s Br. 21. The 

clique members went to one of their apartments, Gil-Bernardez 

 

We decline to consider any arguments not specifically discussed in 

their opening brief, however. Fed. R. App. P. 28(a)(8)(A); see, e.g., 

United States v. Golliher, 820 F.3d 979, 984-85 (8th Cir. 2016) (“We 

may . . . refuse to consider a challenge to a district court’s decision 

to exclude evidence when the appellant fails to direct us to the part 

of the record that contains the substance of the excluded evidence, 

especially when the substance is necessary to evaluate admissibility 

under the Federal Rules of Evidence.”); Guillemard-Ginorio v. 

Contreras-Gomez, 585 F.3d 508, 534 (1st Cir. 2009) (holding that 

evidentiary challenges were waived due to failure to cite “relevant 

portions of the appendix or transcript”).
9

grabbed his backpack, and then they went looking for the three 

rival gang members. J.A. 1240. Urrutia-Barrera testified that 

once they found Wilson, Cook, and Beck, they parked the car

and started walking toward them, and Gil-Bernardez shot at 

them J.A. 1240-41. Urrutia-Barrera testified that the gun 

Gil-Bernardez used was the same one used in the Riverdale, 

Maryland shooting. J.A. 1242. A victim of the shooting also 

testified to the incident during trial. J.A. 1212-15. 

Shootings in Sterling, Virginia. Urrutia-Barrera testified 

about two shootings that occurred in August and September 

2008, in Sterling, Virginia. J.A. 1236. On cross-examination, 

with respect to the first shooting, he testified that he was with 

two other MS-13 members, looking for rival gang members. 

J.A. 1253. When they found the chavalas, Urrutia-Barrera shot 

them. Id. Urrutia-Barrera testified that he shot the chavalas on 

Gil-Bernardez’s instruction. J.A. 1254. 

Armed Gang Fight on October 16, 2009. Special Agent 

Brendan Shelley and co-conspirator Manuel Saravia, a member 

of the Normandie clique, testified regarding a fight between 

MS-13 members and a group of individuals that occurred on

October 16, 2009, in Wheaton, Maryland. J.A. 1331-34, 

1429-30. The MS-13 members were armed with bolt cutters 

and other weapons. J.A. 1429-30. The fight broke up when 

law enforcement arrived. J.A. 1334-35, 1430.

Shooting of Glorisnel Sorto. Saravia testified that he and 

co-conspirator Lopez-Ramirez, also a member of the Normandie 

clique, shot Sorto, a rival gang member, on December 9, 2009, 

in Washington, D.C. J.A. 1430-37; see also J.A. 1351-53 

(testimony of a Government witness regarding the incident). 

The Normandie clique reimbursed the price of the gun used in 

the shooting. J.A. 1433. 
10

None of the witnesses linked any of the incidents to any 

specific defendant, but all involved the Normandie clique.

B.

As a preliminary matter, the parties dispute the standard of 

review the Court is to apply. Appellants urge this Court to 

review their challenges to the admission of this evidence for an 

abuse of discretion. Appellants’ Br. 34. Appellee, however, 

contends that this standard applies only to objections that have 

been preserved, and argue that Appellants preserved their 

objections only as to the Chavez-Ponce murder and the Reston 

triple shooting. Appellee’s Br. 25-26. Accordingly, the 

Government states that the Court should review the admission 

of the evidence regarding the Chavez-Ponce murder and the 

Reston triple shooting for abuse of discretion, but apply the 

plain-error standard to the admission of the other evidence. Id. 

Appellants maintain that they “persistently objected” to the 

admission of the challenged testimony. Appellants’ Br. 36 

n.28.

Appellants are correct; at various times before and during 

trial, Appellants objected to the evidence summarized above, 

as well as other similar evidence, on the grounds that it was 

irrelevant and/or unduly prejudicial.2 See, e.g., J.A. 954-58 

(denying Machado-Erazo’s and Martinez-Amaya’s motion to 

exclude any Rule 404(b) evidence), 1211-12 (objecting to the 

introduction of testimony regarding the Reston triple shooting),

1488-89 (objecting to testimony regarding the Sorto shooting), 

1342-43 (objecting to evidence related to the murder of 

 

2 The District Court ruled that all defendants would be deemed to 

join any motion or objection made by a co-defendant during trial. 

J.A. 80. Accordingly, who made the objection is irrelevant for our 

purposes. 
11

Chavez-Ponce); United States v. Ayala, No. 10-cr-256, ECF 

No. 342 (D.D.C. filed May 21, 2013) (motion to exclude coconspirators’ statements); United States v. Flores, No. 10-cr256, ECF No. 165 (D.D.C. filed May 10, 2012) (motion to 

exclude irrelevant and prejudicial gang evidence); United 

States v. Machado-Erazo, No. 10-cr-256, ECF No. 143 

(D.D.C. filed May 5, 2012) (motion in limine to preclude 

admission of co-conspirators’ evidence). Accordingly, we

review the admission of the evidence for abuse of discretion. 

United States v. Johnson, 519 F.3d 478, 483 (D.C. Cir. 2008).

C.

Rule 404(b) provides that “[e]vidence of a crime, wrong, 

or other act is not admissible to prove a person’s character in 

order to show that on a particular occasion the person acted in 

accordance with the character.” Fed. R. Evid. 404(b)(1). Yet 

the rule permits such evidence for other purposes, including 

proof of motive, intent, knowledge, identity and absence of 

mistake. Fed. R. Evid. 404(b)(2). Indeed, “Rule 404(b) is a 

rule of inclusion rather than exclusion,” United States v.

Bowie, 232 F.3d 923, 929 (D.C. Cir. 2000), “prohibiting the 

admission of other crimes evidence ‘in but one circumstance’ 

– for the purpose of proving that a person’s actions conformed 

to his character,” United States v. Crowder, 141 F.3d 1202, 

1206 (D.C. Cir. 1998) (en banc) (quoting United States v. 

Jenkins, 928 F.2d 1175, 1180 (D.C. Cir. 1991)). “Rule 404(b) 

thus is not so much a character rule as a special aspect of 

relevance” because it “does not prohibit character evidence 

generally, only that which lacks any purpose but proving 

character.” Bowie, 232 F.3d at 930. 

Thus, a threshold question in determining the admissibility 

of evidence of other crimes and bad acts is whether the 

evidence, in actuality, relates to acts unconnected with those 
12

for which the defendant is charged, or instead is intertwined 

with the commission of charged crimes. Acts “extrinsic” to the 

crime charged are subject to Rule 404(b)’s limitations; acts 

“intrinsic” to the crime are not. See Bowie, 232 F.3d at 

927; see also United States v. Mahdi, 598 F.3d 883, 891 (D.C. 

Cir. 2010). 

In conspiracy prosecutions, the prosecution is “usually 

allowed considerable leeway in offering evidence of other 

offenses ‘to inform the jury of the background of the 

conspiracy charged . . . and to help explain to the jury how the 

illegal relationship between the participants in the crime 

developed.’” United States v. Mathis, 216 F.3d 18, 26 (D.C. 

Cir. 2000) (quoting United States v. Williams, 205 F.3d 23, 

33-34 (2d Cir. 2000)). In addition, “where the incident offered 

is a part of the conspiracy alleged[,] the evidence is admissible 

under Rule 404(b) because it is not an ‘other’ crime.” United 

States v. Hemphill, 514 F.3d 1350, 1357 (D.C. Cir. 2008) 

(quoting United States v. Mejia, 448 F.3d 436, 447 (D.C. Cir. 

2006)). This Court has also permitted the introduction of 

“other acts” evidence in conspiracy cases to link a defendant to 

other defendants and drug transactions for which the 

conspiracy was responsible, United States v. Gaviria, 116 F.3d 

1498, 1532 (D.C. Cir. 1997) (per curiam); to show the nature 

of a conspiracy and “the kind of organizational control” a 

defendant exercised, Mahdi, 598 F.3d at 891; and to show the 

defendants’ intent to act in concert, Mathis, 216 F.3d at 26; see 

also United States v. Straker, 800 F.3d 570, 590 (D.C. Cir. 

2015) (per curiam) (evidence of uncharged hostage takings was 

“relevant to . . . how those defendants started to work together 

as kidnappers”). 

The Government contends that because the conspiracy

was defined as MS-13 more generally, and MS-13 activities in 

the United States extend back to the late 1990s, evidence of 
13

MS-13 activity anywhere is admissible under Rule 404(b), 

subject only to Rule 403’s limitations. Oral Arg. 58:10-59:25. 

Fortunately, we need not decide whether the Government’s 

capacious determination of how a conspiracy can be defined 

and how it relates to Rule 404(b) is correct because under this 

Court’s precedent and the definition of the conspiracy here, the 

challenged acts were intrinsic evidence of the RICO conspiracy 

– the evidence helped prove the nature of the conspiracy and 

the purpose of the enterprise. J.A. 125 (defining the conspiracy 

as all of the illicit activities of members of MS-13 in the 

District of Columbia (“La Hermandad”)). Indeed, three of the 

purported other crimes – the Chavez-Ponce murder, the Reston 

triple shooting, and the Sorto shooting – were specifically 

charged in the indictment as overt acts of the conspiracy, see 

J.A. 131-33, and therefore do not constitute “other crimes,” see 

United States v. McGill, 815 F.3d 846, 879 (D.C. Cir. 2016) 

(per curiam).

Moreover, the challenged acts and the acts in which 

defendants were alleged to have actively participated are in 

close temporal proximity. The timeframe for the challenged 

acts spans July 2008 through December 2009. The evidence, 

taken in the light most favorable to the Government, shows that 

Machado-Erazo and Martinez-Amaya were members of the 

Normandie clique by at least December 2008. J.A. 1082 

(Solorzano (aka “Cocky”) became clique leader when 

Gil-Bernardez (aka “Pando”) was arrested in December 2008), 

1736-37 (Avila testified he knew Machado-Erazo from at least 

when Cocky took over the clique), 1244 (Martinez-Amaya 

(aka “Crimen”) was sent to the area when Gil-Bernardez was 

arrested), 1598 (Martinez-Amaya was part of the clique before 

Solorzano became leader). The evidence also shows that Ayala 

was the leader of the Sailors clique in 2008. J.A. 1179, 1121, 

1110. The evidence also showed that the Sailors and 

Normandies worked together to further the goals of MS-13. 
14

See, e.g., J.A. 1079 (discussing cooperation between Sailors and

Normandies), 1085 (Sailors attended a Normandie clique 

meeting), 1111-12 (Sailors and Normandies were in contact 

with each other), 1117-18 (if one clique put a green light on 

someone, members of other cliques were obligated to act on 

the green light), 1724-28 (Sailors and Normandies fought 

together). “[W]here the incident[s] offered [are] part of the 

conspiracy alleged . . . the evidence is admissible under Rule 

404(b) because it is not an ‘other’ crime.” Mejia, 448 F.3d at 

447; Bowie, 232 F.3d at 929.

The determination that this evidence does not constitute 

impermissible character evidence does not end the inquiry. 

Once a defendant raises a 404(b) objection, the district court 

must balance the probative value of the evidence against the 

risk of unfair prejudice. McGill, 815 F.3d at 883; United States 

v. Lavelle, 751 F.2d 1266, 1279 (D.C. Cir. 1985) (requiring a 

district court “to make an on-the-record determination” of 

whether the probative value of other-bad-acts evidence 

outweighs its prejudicial impact”). The District Court did not 

explicitly do so here, and this failure is particularly concerning 

where, as discussed above, the Government takes the broad 

position that evidence regarding MS-13 activity anywhere in 

the United States since the 1980s is admissible under Rule 

404(b). The Government’s position highlights the importance 

of the district court performing the requisite Rule 403 

balancing on the record. 

Nevertheless, because “the factors upon which the 

probative value/prejudice evaluations were made are readily 

apparent from the record, and there is no substantial 

uncertainty about the correctness of the ruling,” reversal is not 

required. McGill, 815 F.3d at 883 (citation and quotation 

marks omitted). The evidence here related solely to acts 

involving the Normandie and Sailors cliques and only during 
15

time periods where one or more defendants were active in the 

cliques. Indeed, comparable other evidence was presented 

showing Appellants’ involvement in other acts of violence 

committed by the gang, including: testimony connecting Ayala 

with the murders of Louis Membreno-Zelaya and Giovanni 

Sanchez, J.A. 1044-49, 1171, 1267-82, 1329-30, and 

Machado-Erazo and Martinez-Amaya with the murder of 

Felipe Enriquez, J.A. 1397-1404, 1476-77. Other evidence 

showed that murder, both threatened and actualized, is central 

to MS-13’s control over its members and its ability to 

intimidate non-members. See, e.g., J.A. 989-92, 1616, 1738, 

1741, 1795. This evidence “dissipate[d] any prejudice 

associated” with the challenged evidence. McGill, 815 F.3d at 

884.

Accordingly, we conclude that the District Court did not 

abuse its discretion by allowing the admission of the 

challenged evidence.

III.

Machado-Erazo and Martinez-Amaya also challenge the 

testimony of the Government’s cell-site expert, FBI Special 

Agent David Magnuson. Magnuson’s testimony was offered 

to show that the cell phones used by Machado-Erazo, 

Martinez-Amaya, and a cooperating witness were in the 

vicinity of the remote area where the body of Felipe Enriquez 

was found on or about March 28, 2010, the date Enriquez was 

believed to have been killed. United States v. Machado-Erazo, 

950 F. Supp. 2d 49, 51 (D.D.C. 2013). Magnuson’s report 

depicted the geographic location of the cell towers used by the 

phones and analyzed the phones as they moved through the 

Cricket and T-Mobile cellular networks. Id. 
16

Appellants contend that the District Court erred by 

allowing Magnuson’s testimony because the Government 

deviated from its initial notice regarding Magnuson’s 

testimony by proffering opinions about specific distances 

rather than broad ranges, Magnuson’s testimony exceeded the 

bounds of his expertise, and the Government’s subsequent 

notice regarding specific location testimony was untimely. We 

review for abuse of discretion a district court’s evidentiary 

rulings concerning the admission of expert testimony. United

States v. Day, 524 F.3d 1361, 1369 (D.C. Cir. 2008) (citing 

Kumho Tire Co. v. Carmichael, 526 U.S. 137, 152 (1999)). 

However, “[e]ven when the [D]istrict [C]ourt has abused its 

discretion, reversal is appropriate only upon a concomitant 

finding that the error affected appellant’s ‘substantial rights.’” 

See English v. Dist. of Columbia, 651 F.3d 1, 7 (D.C. Cir. 2011) 

(citation omitted); see also Kotteakos v. United States, 328 

U.S. 750, 764-65 (1946).

For the reasons discussed below, we find that the District 

Court abused its discretion by allowing Agent Magnuson to 

testify regarding specific distances and ranges of distances 

because such testimony was neither disclosed pursuant to 

Federal Rule of Criminal Procedure 16, nor vetted as required 

by Federal Rules of Evidence 702 and 403. Nevertheless, 

because the error was harmless, reversal is not warranted. 

A.

Before submitting their joint pretrial statement, the 

Government provided notice, see Fed. R. Crim. P. 16(a)(1)(G), 

that it intended to call Magnuson as an expert in cellular 

technology and the analysis of historical cellular telephone and 

cell site records. The Government also produced a copy of 

Magnuson’s report – a series of maps with annotations but little 

explanatory text – which it contended showed the activity of 
17

cell phones used by Machado-Erazo, Martinez-Amaya, and 

Saravia on the day of the Enriquez murder. 

Approximately one week before trial, Machado-Erazo

moved to exclude Agent Magnuson’s testimony, arguing that 

the testimony was not based on a sufficiently reliable 

methodology as required by Rule 702 and that it would 

therefore be unduly prejudicial and excludable pursuant to 

Rule 403. See generally Machado-Erazo, 950 F. Supp. 2d 49. 

The Government opposed Machado-Erazo’s motion, and 

asserted that Magnuson was a highly trained agent whose 

testimony was firmly based in scientific principles. The 

Government emphasized that Magnuson would not claim to 

have determined the exact location of the phone user, but rather 

the general location where a cell phone would have to be 

located to use a particular cell tower and sector. Government’s 

Opposition to Defendant’s Motion in Limine to Exclude Expert 

Testimony and Cellular Report of FBI Special Agent David 

Magnuson, United States v. Machado-Erazo, No. 10-cr-256, 

ECF No. 368 (D.D.C. filed June 12, 2013). 

The District Court denied Machado-Erazo’s motion in 

limine. See generally Machado-Erazo, 950 F. Supp. 2d 49. In 

addition to rejecting Appellants’ “fundamentally erroneous 

contention . . . that a cell phone always connects to the closest 

tower at the time a call is placed,” the District Court determined 

that “th[e] methodology employed by [ ] Magnuson clears the

hurdle imposed by Daubert and [Federal Rule of Evidence] 

702.” Id. at 55, 56. The District Court relied on United States 

v. Jones, 918 F. Supp. 2d 1 (D.D.C. 2013) (rejecting similar 

arguments on a motion to exclude cell-site analysis), and 

United States v. Davis, No. 11-60285-CR, 2013 WL 2156659 

(S.D. Fla. May 17, 2013) (permitting Magnuson to offer the 
18

exact same type of testimony offered here after a Daubert 

hearing).3 

During trial, which occurred before a different district 

judge, Machado-Erazo renewed his objection based on Rule 

702. He also argued that the government failed to timely 

disclose that Magnuson would estimate a coverage range for 

the cell towers. J.A. 1497-98. The Government responded that 

the purported disclosure merely “describe[d] how [Magnuson] 

went about making his report,” and emphasized that Magnuson 

would discuss only the “general range of the cell towers,” not 

the specific location of a person, which was already endorsed 

by the District Court. Id. at 1498-99. The District Court 

overruled Machado-Erazo’s objection, and permitted 

Magnuson to testify. 

B.

Notwithstanding the Government’s representation to the 

District Court, the Government elicited testimony from 

Magnuson about precise locations of the cell phones he 

analyzed. See J.A. 1497-98 (testifying to “a coverage range for 

the cell towers”), 1518-19 (testifying that the two phones were 

“very close” to a particular cell tower at the time of the 

murder), 1520 (testifying that that the phones were within “a 

half mile of th[e] tower” at the time of the murder), 1532-33 

(testimony regarding the “proximity between th[e] two 

phones” at the time of the murder). Appellants contend that 

 

3 Appellants do not challenge the District Court’s denial of the 

pretrial motion in limine. Instead, they claim only that the specific 

location testimony offered at trial exceeded the Government’s 

proffer and Magnuson’s expertise. Oral Arg. 5:36-6:20 (conceding 

that their concern was not with the general methodology of collecting 

and interpreting cell-site data, but rather with the specific location 

testimony).
19

admission of this testimony constituted an abuse of discretion. 

We agree. 

Under Federal Rule of Criminal Procedure 16(a)(1)(G), 

“the government must give to the defendant a written summary 

of any testimony that the government intends to use under 

Rule[] 702 . . . during its case-in-chief at trial. The summary 

. . . must describe the witness’s opinions, the bases and reasons 

for those opinions, and the witness’s qualifications.” The 

Government provided no such disclosure here. Indeed, the 

only summary provided pre-trial was a series of slides showing 

the location of cell towers and the cell sector for particular calls 

without explanation. J.A. 284-321. The briefing on the motion 

in limine did little to clarify the scope of Agent Magnuson’s 

testimony, noting only that “[the] proposed testimony will not 

claim to have determined the exact location of the phone user,” 

J.A. 639 n.1. The Government’s disclosure and statements, 

then, left both the District Court and the parties to presume 

what the testimony would be. This, in and of itself, shows that 

the notice was deficient under Rule 16. Nevertheless, based 

upon a reported decision admitting Magnuson’s testimony in 

another jurisdiction, as well as other decisions admitting other 

cell-site expert testimony, the District Court inferred the bases 

and reasons underlying Magnuson’s opinions and denied the 

motion in limine. Machado-Erazo, 950 F. Supp. 2d at 53-58. 

Critically, the ruling was based upon the understanding that 

Magnuson would offer testimony about only the “general 

location” of cell phones, rather than precise locations. Id. At 

trial, before a different judge, the Government shifted gears and 

elicited testimony about more precise locations. By admitting 

this expert testimony without giving defendants sufficient prior 

notice and without first finding it to be relevant and reliable 

under Daubert, the District Court abused its discretion. See 

Estate of Barabin v. AstenJohnson, Inc., 740 F.3d 457, 464 (9th 

Cir. 2014) (en banc).
20

That the District Court abused its discretion does not end 

the inquiry, as “reversal is appropriate only upon a concomitant 

finding that the error affected appellant’s ‘substantial rights.’” 

See English, 651 F.3d at 7 (citation omitted). An error affects 

the appellant’s substantial rights if it influenced or tainted the 

outcome of the district court proceedings. United States v. 

Olano, 507 U.S. 725, 734 (1993); United States v. Smith, 232 

F.3d 236, 243 (D.C. Cir. 2000). As the Supreme Court noted 

in Kotteakos, “[t]he inquiry cannot be merely whether there 

was enough to support the result, apart from the phase affected 

by the error. It is rather, even so, whether the error itself had 

substantial influence. If so, or if one is left in grave doubt, the 

conviction cannot stand.” 328 U.S. at 765. Where the Court is

sure “that the error did not influence the jury, or had but very 

slight effect, the verdict and the judgment should 

stand.” Id. Magnuson’s expert testimony related solely to the 

murder of Felipe Enriquez. Given the breadth of evidence 

linking Machado-Erazo and Martinez–Amaya to the murder, 

much of which was undisputed, we find that admission of the 

challenged testimony was not prejudicial, and therefore 

reversal is not appropriate.

At trial, the Government presented the following 

undisputed and unchallenged evidence. First, Saravia, the 

Government’s key witness, testified that during a clique 

meeting on March 6, 2010, Enriquez (aka “Zombie”) 

disrespected Solorzano (aka “Cocky”), then-leader of the 

Normandie clique, and brought a knife to the meeting, which 

violated MS-13 rules. J.A. 1397-99. The Government 

submitted an audio recording of the clique meeting 

corroborating this testimony. See J.A. 826-877, 1737. This 

evidence provided the motive for the murder. Second, the 

Government presented wiretaps of a phone call during which 

Solorzano, Machado-Erazo, and Saravia discussed Enriquez’s 
21

behavior and agreed to call Rivera-Luna (aka “Viejo Santos”), 

who oversaw MS-13’s activities in the Washington, D.C. area 

from an El Salvadorian jail, as well as a phone conversation 

during which Viejo Santos put a green light on Enriquez. J.A. 

1744. Third, the location of the murder is undisputed. During 

trial, a detective testified that Enriquez’s body was discovered 

in a wooded area off Ednor Road, near the Patuxent River, J.A. 

1382-84, 1491, 1494, and that police recovered eight 

9-millimeter cartridge casings near his body, J.A. 1387. Agent 

Magnuson’s testimony further showed that phones linked to 

Saravia, Machado-Erazo, and Martinez-Amaya were 

connected to cell towers located nearest to the murder site at 

approximately the same time or close in time to each other. 

J.A. 1512-34. His permissible testimony also showed that 

phones linked to Machado-Erazo and Saravia were connected 

to the cell tower closest to Machado-Erazo’s home prior to the 

time that the three phones were connected to the towers near 

where the murder occurred. Thus, Magnuson’s permissible 

testimony corroborated Saravia’s testimony that he and 

Machado-Erazo met before the murder and drove to the site of 

the murder together. J.A. 1402-16. Given this evidence, we 

cannot say that the District Court’s erroneous admission of 

portions of Agent Magnuson’s testimony affected Appellants’ 

“substantial rights.” We therefore reject Appellants’ 

contention that their VICAR and firearm convictions should be 

reversed based on Magnuson’s improper testimony. 

* * *

For the foregoing reasons, we affirm.
ROGERS, Circuit Judge, concurring: I join the court’s 

opinion holding that the district court abused its discretion by 

allowing Agent Magnuson to testify as an expert witness 

regarding specific cell tower distances and ranges of distances. 

I write briefly on the relationship between the district court’s 

“gatekeeping” obligation under Federal Rule of Evidence 702 

and the government’s disclosure obligations upon defense 

request under Federal Rule of Criminal Procedure 16(a)(1)(G).

I.

A witness may testify as an expert only if 

(a) the expert’s scientific, technical, or other 

specialized knowledge will help the trier of fact to 

understand the evidence or to determine a fact in 

issue; (b) the testimony is based on sufficient facts or 

data; (c) the testimony is the product of reliable 

principles and methods; and (d) the expert has reliably 

applied the principles and methods to the facts of the 

case.

FED.R.EVID. 702. The district court mustserve as a gatekeeper 

to the admission of expert testimony. Daubert v. Merrell Dow 

Pharm., Inc., 509 U.S. 579, 597 (1993). Although perhaps 

originally spawned by concerns about “junk science” 

masquerading as science, see Gen. Elec. Co. v. Joiner, 522 U.S. 

136, 153 (1997) (Breyer, J., concurring), the “gatekeeper role” 

ensures more broadly that witnesses possess the relevant 

training or experience in the field of expertise on which they

will testify, and that, if found qualified, their testimony stays 

within the realm of their expertise. “[T]o ensure the reliability 

and relevancy of expert testimony,” Kumho Tire Co., Ltd. v. 

Carmichael, 526 U.S. 137, 152 (1999), the district court has a 

threshold obligation to independently determine whether and to 

what extent a witness can testify as an expert, as well as a 

continuing responsibility to ensure, upon defense objection, 
2

that the expert’s testimony stays within permissible bounds. 

The heightened aura and weight to which a fact finder is likely 

to attach to expert testimony, as compared to lay testimony, cf. 

United States v. Williams, 827 F.3d 1134, 1160-61 (D.C. Cir. 

2016), warrants the two-part nature of the gatekeeper role. 

The district court’s ability to fulfill its gatekeeping 

obligations is not unrelated to the government’s compliance 

with Federal Rule of Criminal Procedure 16. Rule 16 states in 

relevant part:

At the defendant’s request, the government must give 

to the defendant a written summary of any testimony 

that the government intends to use under Rules 702, 

703, or 705 of the Federal Rules of Evidence . . . The 

summary provided under this subparagraph must 

describe the witness’s opinions, the bases and reasons 

for those opinions, and the witness’s qualifications.

FED. R. CRIM. P. 16(a)(1)(G). 

This disclosure mandate is designed to “minimize surprise 

that often results from unexpected expert testimony, reduce the 

need for continuances, and to provide the opponent with a fair 

opportunity to test the merit of the expert’s testimony through 

focused cross-examination.” Adv. Comm. Note to 1993 

Amendment. Further, prompt notice of a putative expert’s 

qualifications “will permit the requesting party to determine 

whether in fact the witness is an expert within the definition of 

Federal Rule of Evidence 702.” Id. The Rule reflects a trend 

toward “freer disclosure” in criminal procedure. 2 CHARLES 

ALAN WRIGHT & ARTHUR R. MILLER, FEDERAL PRACTICE &

PROCEDURE § 251 (4th ed. 2018). 
3

The Rule provides the district court with a range of 

remedial options: a continuance, exclusion of the evidence, or 

“any other order that is just under the circumstances.” FED. R.

CRIM. P. 16(d)(2). The district court’s rulings under Rule 16 

and FRE 702 are reviewed for abuse of discretion, United 

States v. Day, 524 F.3d 1361, 1367, 1370 (D.C. Cir. 2008), and 

an error is harmless if there was no “substantial and injurious 

effect or influence in determining the jury’s verdict,” Kotteakos 

v. United States, 328 U.S. 750, 776 (1946).

II.

What is striking in the instant case is how the government’s 

failure to disclose promptly its proposed expert’s opinions and 

the bases for those opinions can hamstring the district court’s 

effort to separate reliable expert testimony from “junk science.” 

On June 10, 2011, defense counsel, by letter to the trial 

prosecutors, requested “a written summary of any expert 

testimony which the government intends to use under Rule[] 

702 . . . in its case-in-chief at trial.” The joint pretrial statement 

of May 21, 2013, indicated that FBI Special Agent David 

Magnuson would testify as an expert in historical cell-site 

analysis. Approximately one month before trial, the 

government turned over its expert’s “report.” This consisted of 

a series of maps where cell tower locations and angles were 

plotted; no “written summary” describing the nature of 

Magnuson’s opinion was included. 

Defense counsel moved to exclude Magnuson’s testimony

as an expert, arguing his testimony relied on a methodology 

that was “unreliable and irrelevant,” and requested a hearing. 

Agent Magnuson’s report does not describe the bases 

and reasons for his opinions or the inferences he 

draws. See Fed. R. Crim. P. 16(a)(1)(G). The report 
4

merely plots the presumed locations from which calls 

were made, the cell tower from which the call 

registered at its origin, and the relation to the crime 

scenes charged in this case. There is no indication 

how these plotted called are placed on the map or what 

determined their placement. The cell towers to which 

certain cell phones connected on a map have been 

used by Agent Magnuson to assume a basic coverage 

area. This is not supported by the facts or record in 

this case.

Def.’s Mot. to Exclude the Expert Testimony and Cellular 

Analysis Report and Charts of Special Agent David Magnuson 

(June 12, 2013) (“Motion to Exclude”) at 2-3. Further, the 

defense argued that if Magnuson “testifies only to the cell 

tower location and side of the cell tower antennae that received 

the call,” then he will be “acting not as an ‘expert’ but merely 

as a summary witness.” Id. at 13. Referencing Magnuson’s

prior expert testimony, the defense also suggested that if 

allowed to testify as an expert he “may attempt to go far beyond

this summary testimony.” Id. 

In opposing the Motion to Exclude, the government 

represented that Magnuson “will not claim to have determined 

the exact location of the phone user, but rather the general 

location where a cell phone would have to be located to use a 

particular cell tower and sector.” Gov’t Opp’n to Def.’s Mot. 

to Exclude Expert Testimony (“Gov’t Opp’n”) (June 12, 2013). 

Further, claiming neither a Daubert hearing nor peer review of 

the cell-site methodology was needed because it had been 

approved by a number of district court judges, the government 

also did not describe how Magnuson would use the cell tower

locations in his “report” to project the likely area where a cell

phone was located. The district court denied the defense

motion, relying on the government’s representations, 
5

Magnuson’s “report,” and prior district court rulings allowing 

expert testimony on cell-site analysis. See United States v. 

Machado-Erazo, 950 F. Supp. 2d 49, 55-58 (D.D.C. 2013).

Hours before Magnuson was scheduled to testify on the 

eighth day of the trial before a jury, the government turned over 

to the defense a document titled “Basic Principals [sic] Utilized 

in Record Analysis.” It stated: “As a GENERAL RULE, most 

towers (depending on the environment) have a radius of 

approximately ONE or TWO MILES (greater or less distances 

are also common).” Defense counsel objected to the late 

disclosure and requested that Magnuson be treated as a lay 

witness. The district court permitted Magnuson to testify as an 

expert after the prosecutor represented Magnuson would testify

only “as to the general range of the cell towers” and that the 

issue had been ruled on when the Motion to Exclude was 

denied. Trial Tr. 25-26 (July 8, 2013). Magnuson testified at 

length over two days (91 transcript pages) as an expert at 

appellants’ trial. His testimony included a discussion of the 

areas where cell phones belonging to appellants and a coconspirator were located on the day of Felipe Enriquez’s 

murder. Magnuson also testified that a cell phone “had to be 

within a half mile” of a particular cell tower for the phone to 

connect to that tower. Id. at 51. On that basis, a cell phone 

belonging to the co-conspirator was located near MachadoErazo’s home on the day of the murder.

III.

At the point the district court would have had to make its 

threshold gatekeeping determination for purposes of FRE 702, 

the government had yet to disclose the “written summary” of 

its expert’s testimony as required by Rule 16(a)(1)(G). The 

record does not reveal exactly why. Defense counsel had 

alerted the government to its obligation under Rule 16(a)(1)(G)
6

two years before trial, and Magnuson was a federal employee

who had previously testified as an expert. To the extent the 

trial Assistant U.S. Attorney advised the district court that he 

had only obtained the document explaining cell-site analysis 

methodology shortly before Magnuson testified on the eighth 

day of the jury trial, that did not absolve the government of its 

obligations under Rule 16. The government’s “dribbling out”

of information about the nature and scope of its expert’s 

testimony never quite described the level of detail on which

Magnuson would testify at trial, much less the methodology he 

used, potentially leaving defense counsel unclear about the 

nature and scope of his expert testimony. 

The consequence pertinent here is that the government’s 

conduct interfered with the district court’s ability to fulfill its 

gatekeeping role under Daubert and FRE 702. It hampered the 

district court in assessing with any measure of certainty 

whether the expert’s testimony would be reliable much less, as 

defense counsel feared, would stray at trial beyond the contents 

of his “report.” Neither Magnuson’s “report” nor the 

government’s representations described the methodology that 

he would use to connect appellants’ cell phones to the cell

tower locations. The district court attempted to fill this gap by 

relying on descriptions of cell-site methodology in other cases. 

This assumed Magnuson’s methodology would be the same in 

appellants’ case and limited the court’s ability to pose inquiries 

of its own. In opposing the Motion to Exclude, the government 

implicitly invited this flawed approach by emphasizing that 

cell-site analysts had been accepted as experts by other district 

court judges, by arguing that the case appellants relied on where 

the district court rejected cell-site expert testimony was 

different, and by asserting that peer review was unnecessary 

because “cell phone technology is neither novel nor particularly 

complex.” Gov’t Opp’n at 6. Although a witness’s testimony 

as an expert on a general subject matter in another case may 
7

inform the Daubert analysis, that circumstance is not sufficient. 

The district court’s “gatekeeping inquiry must be tied to the 

facts of a particular case.” Kumho Tire, 526 U.S. at 150 

(internal quotations omitted). Indeed, “judicial acceptance is 

not relevant; what matters is general acceptance in the relevant 

expert (scientific or otherwise) community.” United States v. 

Hill, 818 F.3d 289, 297 (7th Cir. 2016). 

The district court judge who denied the Motion to Exclude 

found Magnuson’s expert opinion reliable based principally on 

cell-site analyses accepted by two other district court judges. 

Machado-Erazo, 950 F. Supp. 2d at 55-58 (citing United States 

v. Jones, 918 F. Supp. 2d 1 (D.D.C. 2013); United States v. 

Davis, No. 11-60285-CR, 2013 WL 2156659 (S.D. Fla. May 

17, 2013)). In Jones, the district court allowed an FBI agent to 

testify as an expert because his cell-site analysis was based on

a reliable methodology, which the government had “clearly 

explain[ed],” and the agent did “not purport to portray the 

‘coverage area’ of any particular cell tower or antenna.” 918 

F. Supp. 2d at 45. In Davis, the district court found, after 

holding a Daubert hearing, that Magnuson was “qualified to 

opine on call detail records” and “the areas most likely to fall 

within the sector serviced by a particular cell tower,” by reason 

of his “knowledge, skill, experience, training, and education.” 

2013 WL 2156659, at *4. 

If Daubert is to have meaning, then district court had to

satisfy itself that the witness in appellants’ case was an expert 

on a particular subject based on the witness’s actual

methodology and the scope of the opinions the witness would 

offer at trial. The expert’s testimony in Jones was limited in 

scope, and the district court could not assume Magnuson’s 

testimony would be the same in appellants’ case as in Davis. 

The government’s Rule 16 disclosures and vague 

representations were unhelpful in this respect; they did “not . . . 
8

clearly indicat[e] the level of precision — or imprecision —

with which [cell-site] evidence pinpoints a person’s location at 

a given time.” Hill, 818 F.3d at 299. Further, while defense

counsel had alerted the district court to potential flaws in 

Magnuson’s methodology, the district court found none,

relying not on the government’s explanation of the 

methodology he would use in appellants’ case, but on the

description of his methodology in Davis. See Machado-Erazo, 

950 F. Supp. 2d at 55-56. Consulting other judges’ analyses

may be informative or persuasive, but not dispositive. Absent 

an independent evaluation of the expert’s methodology and the 

nature of the expert’s proposed testimony, real life tragedies 

can occur. See, e.g., Pamela Colloff, He Has Spent Three 

Decades in Prison. Now Experts Dispute the Evidence., N.Y.

TIMES, July 24, 2018; see also Leora Smith, How an Unproven 

Forensic Science Became a Courtroom Staple, PROPUBLICA, 

May 31, 2018.

For much the same reason, Daubert’s monitoring

obligation was frustrated. The district court judge who 

presided at appellants’ trial relied on the pretrial Daubert 

ruling, which in turn relied on rulings in other cases, including

one that involved a narrower use of a cell-site expert than

occurred at appellants’ trial and another that did not reveal the 

scope of Magnuson’s expert testimony. Those rulings could 

not eliminate the need to independently monitor the expert’s 

testimony at appellants’ trial. Notwithstanding defense 

counsel’s alert that Magnuson’s expert testimony could stray 

beyond the government’s Rule 16 pretrial disclosure of his 

“report,” cf. United States v. Moore, 651 F.3d 30, 60 (D.C. Cir. 

2011), Magnuson was allowed to opine that a cell phone “had 

to be within a half mile” of a particular tower. Trial Tr. 51 (July 

8, 2013). Yet the maps in Magnuson’s “report” contained no 

measuring scale and the document produced on the eighth day 

of trial stated only that the general range of a cell tower is 
9

“approximately ONE or TWO miles (greater or less distances 

are also common).” Magnuson claimed the basis for his 

opinion was “the very nature of the cellular network, the fact 

that it’s divided up into cells of [radio frequency] energy.” 

Trial Tr. 51 (July 8, 2013). How Magnuson derived “within a 

half mile” from those vague statements was explained neither 

for the jury nor earlier for the district court. Absent a 

foundation, Magnuson’s half-mile opinion was inadmissible

under FRE 702. Even if the district court had remedial 

discretion to deny the defense request that Magnuson be treated 

as a lay witness due to the government’s non-compliance with 

Rule 16, it was error to allow the jury to consider unsupported 

expert testimony.

In appellants’ case, however, the Rule 16 and Daubert

failings do not entitle them to relief because they show no 

prejudice: The government’s evidence of their guilt was strong, 

including wiretap and co-conspirator testimony linking them to 

the murder, Op. 20-21, and the government’s late Rule 16 

disclosures were cumulative of information in its opposition to

the Motion to Exclude. Consequently, “it was highly 

improbable that any changes in the facts could have materially 

changed the conclusion” of the jury at trial. United States v. 

Bresil, 767 F.3d 124, 127 (1st Cir. 2014); see United States v. 

Martinez, 657 F.3d 811, 817 (9th Cir. 2011). Still, what 

happened here with regard to the admission of Magnuson’s 

expert opinion is concerning. Although “the prosecution is 

entitled to prove its case by evidence of its own choice,” Old 

Chief v. United States, 519 U.S. 172, 186 (1997), one-sided 

enforcement of the evidentiary and procedural rules would be

troubling, especially in criminal cases where liberty is at stake.