Appellant, Arnell W. Shelton, was found guilty by a jury of assault with intent to kill while armed,1 aggravated assault while armed,2 two counts of possession of a firearm during a crime of violence,3 carrying a pistol without a license,4 and malicious destruction of property.5 Appellant’s principal claim is that the trial judge did not allow him to introduce evidence of the fact that the government had withheld exculpatory statements made by the complainant during his first trial,6 evidence that the prosecutor-did not disclose until the eve of the second trial. Appellant contends that with that evidence, he could have argued to the jury that in the government’s own view the case against appellant was not as strong as the government purported it to be. The government argues, however, that we should reject that contention because it was not presented to the trial judge and because it lacked substantial merit. We decline to decide whether the claim was meritorious or whether it was properly preserved because, assuming, without deciding, that the trial judge erred in excluding that evidence and argument, any such error was harmless. We therefore affirm.
I. Facts
The government presented evidence that at around 11:00 p.m. on January 14, 2001, Christopher Boyd drove to Melon Street, Southeast, to visit his mother. Boyd stopped in front of her house, where he planned to double-park, and saw his mother standing outside talking to neighbors. Suddenly, a blue “foreign make *218Toyota” raced up along the left side of Boyd’s car. Boyd saw appellant “hanging out the window” of the Toyota, and he soon “was struck by a bullet.”7 Boyd testified that he heard the shots and saw the “fire from the gun.”8 When Boyd tried to drive away, the car that was carrying appellant continued to stay next to him as he traveled down the street. Boyd eventually escaped by turning down an alley.
Boyd drove himself to Greater Southeast Hospital, and passed out. Boyd testified that he was “in and out of consciousness” while at the hospital, and “didn’t really know what was going on at the time.” Boyd “remember[ed] waking up and a police officer [was] in front of [him],” but did not remember having a “conscious conversation” with the officer (Officer Edward Woodward). Boyd was soon transferred to the Intensive Care Unit at Washington Hospital Center for emergency treatment.
Two days after the shooting, Boyd was interviewed by Detective James V. Francis at Washington Hospital Center. Detective Francis asked Boyd if he knew the identity of the person who shot him, to which Boyd unhesitatingly responded: “Arnell White Boy shot me.” Boyd further stated that he had known “Arnell White Bay” [i.e., appellant] for more than five years, and that appellant was the person who had fired the shots from the front passenger seat of the blue Toyota. Boyd again confirmed appellant’s identity when Detective Francis showed him a photo of appellant.
Andrew Durham saw the shooting. He knew appellant and Boyd from the neighborhood, but was not close to either one of them. Durham testified that he saw Boyd “pull[ ] up and ... talk[ ] to some guys in front of his mother’s house.” A couple of minutes later, a “small little Nissan or Honda, ... a small four-door car with tinted windows” drove up beside Boyd’s car. Durham heard gunshots and saw that Boyd was being shot as he sat in his car. The shooter’s car then continued past Boyd’s car, and Durham saw the shooter “lift his head up and look out the window.” 9 Durham recognized appellant as the shooter. He then watched appellant fire additional shots at Boyd as the two cars drove away.
Boyd and his “play cousin,” Myra Ferguson, testified about the events that likely precipitated the shooting.10 In April 2000, about ten months before Boyd was shot, Ferguson had accepted a ride home from appellant, whom she knew from the neighborhood. While they were in the car, appellant tried to kiss and fondle her and to unzip her pants, ripping her underwear in *219the process. When appellant continued the assault after Ferguson told him to stop, she hit him in the groin, got out of the car, and walked home. Ferguson did not tell anyone about this incident because she was “embarrassed about the whole situation” and “really [didn’t] want anyone to know about it.”
A couple of weeks later, Boyd learned of appellant’s sexual assault when appellant talked about it at a party. Boyd eventually told Ferguson’s brother, Derrick, about the incident. Derrick was upset and decided to look for appellant. Derrick Ferguson soon found appellant standing outside on Newcomb Street and confronted him, accompanied by his sister and Boyd. Derrick and appellant started fighting. Appellant then ran inside a building, at which point Derrick Ferguson began “busting [appellant’s] car windows out of his car.” Neither Boyd nor Myra Ferguson helped damage appellant’s car.
Officer Edward Woodward, who had been one of the first officers on the scene after the January 2001 shooting, testified on behalf of appellant at trial. Officer Woodward had also interviewed Boyd at Greater Southeast Hospital approximately 45 minutes after the shooting. During that interview, Boyd did not tell the officer that he had seen or recognized who shot him. Officer Woodward could not remember Boyd’s “exact words, if he said I don’t know or I didn’t see or all’s I saw was ... someone shoot at me from a from a dark-colored car.” Officer Woodward also asked Boyd “if he had a beef with [appellant] earlier in the summer.”11 According to Officer Woodward, Boyd responded that there had been a dispute and that it pertained to “an unwanted sexual advance on one of [Boyd’s] cousins.” Boyd did not, however, state that appellant had also been the one who shot him. Officer Woodward further testified that Boyd “appeared to be in pain, scared, kind of unsure of what was going to happen to him” during the interview.
Appellant presented an alibi defense through the testimony of his wife, Sharia Shelton, who said that appellant had been with her and their seven-month-old daughter watching TV on that Sunday night — a “family day” at their home — when the shooting took place. The prosecutor cross-examined Ms. Shelton and sought to impeach her as biased, because she had refused to tell the prosecutor in the first trial about the alibi after he had called her for any information that could exonerate her husband.
The prosecutor argued in closing that appellant wanted “revenge” because “Christopher Boyd caused him to be shamed and publicly humiliated.” The government’s theory was that appellant viewed Boyd as the instigator, “set[ting] into motion th[e] chain of events,” that led Derrick Ferguson to beat appellant and bash his car in public.
II. Brady Violation
Neither before nor during appellant’s first trial, see note 6, supra, was defense counsel informed that Boyd had failed to identify appellant as the shooter when he was questioned at the hospital, and that Officer Woodward had brought up the “beef’ Boyd had with appellant several months earlier. Indeed, this information was not disclosed until the eve of the second trial, by Assistant United States Attorney (“AUSA”) Wanda Dixon, who *220had replaced AUSA Andrew Kline, the prosecutor who represented the United States during the first trial. Defense counsel informed the trial court of the late disclosure, argued that it was a Brady violation,12 and requested that the case be dismissed. Upon being apprised of the situation, the trial court provided the parties with “a chance to find out ... as much as [possible]” about “where this information [came] from, when it came to the United States Attorney’s Office, why it wasn’t disclosed earlier.”
The following day, the trial judge questioned the prosecutor:
The Court: But I still don’t understand why [defense counsel] did not get [this information] before we went to trial the first time.
Prosecutor: Your Honor, it was [the former prosecutor’s] position that the information was not exculpatory.
The Court: Do you want to explain his rationale (indiscernible)?
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Prosecutor: My understanding is that [the former prosecutor’s] position was based on the thought that there was a reason for the witness to respond in that way. The reason being that the witness was in pain. He had just been taken to the hospital. He was on a gurney, staff attending to him, etc. Your Honor, and if I may also approach the bench ex parte, I have something else I can tell the Court.
(Ex parte bench conference with the Government attorney, Ms. Dixon, which was indiscernible.)[13]
(Open court.)
The Court: When I said I don’t get the first thing, what I meant was [that] given the prosecutor’s obligations under Brady v. Maryland, I don’t see how a prosecutor who states that if a witness says I don’t know who shot me or I didn’t see who shot me or all I saw was a dark car, who’s later going to come into court and say Amell Shelton shot me, I saw it, saw him, should not turn that over because the prosecutor doesn’t think it’s true.
Prosecutor: Yes, Your Honor, and I’m not saying that that’s my position at all. The Court: Well, I mean, I don’t see how any prosecutor could take that position. ... I don’t see how any prosecutor anywhere in any state in the country, could say that I don’t have to turn that over because I think I know why he said that.
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The Court: [I]t wouldn’t have taken me five seconds to figure out that that’s something that the defense was entitled to know.
(Emphasis added.)
The trial judge was “strongly disinclined” to grant (and eventually rejected) the motion to dismiss the case as a “punitive sanction for the failure to turn over” Boyd’s exculpatory statement, but offered to continue the trial date if defense counsel
*221needed additional time to prepare. Counsel stated that she was ready, and declined the offer for a continuance. At trial, defense counsel called Officer Woodward as a witness. After defense counsel elicited the substance of Boyd’s statements from when Officer Woodward interviewed him at the hospital, in cross-examination the government stressed the ambiguities and vagueness of what the officer recalled. On redirect, defense counsel tried to question Officer Woodward about the late disclosure of the exculpatory statement Boyd had made:
Defense Counsel: Officer Woodward, when was the first time you came forward and told us what you knew? [14]
Prosecutor: Objection.
The Court: Who’s the us and—
Defense Counsel: When you spoke to myself and my investigator what you knew?
Prosecutor: Objection, relevance.
The Court: I’ll sustain the objection.
Defense Counsel: Well, Detective, I mean Officer Woodward, it’s fair to say you spoke to me the other day, correct?
Officer Woodward: Yes.
Prosecutor: Objection.
The Court: Wait a minute, I will ask you to come to the bench at this point. (Bench conference.)
The Court: I think I’m going to cut this one off, Miss Rodriques, if you’re going where I think you’re going. What are you up to?
Defense Counsel: I’m going to remind him about what he told us.
The Court: I don’t have any problem with that, ... but the implication that he’s never told anybody is not proper.
Defense Counsel: Implication.
The Court: I don’t want you to go[] into what he told [the first prosecutor], why [he] didn’t tell you, the jury’s not going to hear that.
Defense Counsel: Well, where I did want to go, Your Honor, the Government never told us until two days ago.
The Court: No.
Defense Counsel: Playing dirty.
The Court: Remedy for that was as much time as you needed to prepare for it and you said you were ready, that’s it, there’s no other sanction you’re going to get for [late] disclosure-and—
Defense Counsel: So the court’s ruling is that the jury won’t hear this?
The Court: Correct.
(Close bench conference.)
(Emphasis added.)
III. Analysis
A. Admission by Conduct
Appellant argues on appeal that the trial judge improperly prevented defense counsel from questioning Officer Woodward further in order to bring to the jury’s attention the government’s eleventh-hour disclosure, on the eve of the second trial, that when Officer Woodward first interviewed Boyd at the hospital, Boyd had not identified appellant as the shooter. From this nondisclosure, appellant argues, the jury could have inferred that the government (during the first trial) was concerned that the exculpatory evidence seriously undermined its case. This was not just a reasonable and permissible inference, appellant contends, but a powerful one, because, as the trial court commented, there was no question that the government *222had an obligation to reveal it to the defense before the first trial. That the government so clearly breached its Brady obligation to disclose the information reflects the importance attached to it.
The government contends that we are limited to review for plain error, because appellant is challenging the trial court’s ruling on grounds that were not asserted at trial. See, e.g., Watts v. United States, 971 A.2d 921, 930 (D.C.2009) (citing United States v. Olano, 507 U.S. 725, 113 S.Ct. 1770, 123 L.Ed.2d 508 (1993)). According to the government, although defense counsel asked the trial court to admit into evidence the government’s failure to disclose the exculpatory statements, appellant did not preserve the specific claim he makes on appeal-that he wanted to introduce evidence of the government’s withholding of exculpatory evidence to prove admission by conduct. Appellant, on the other hand, argues that his claim was properly preserved, even if not made with the precision of the argument it has presented on appeal, citing Yee v. Escondido, 503 U.S. 519, 534, 112 S.Ct. 1522, 118 L.Ed.2d 153 (1992), and a number of our cases that have applied it. Specifically, appellant contends that by saying “playing dirty” after the judge sustained the government’s objection based on relevance, defense counsel let the trial court know (albeit in a short-hand way) that the evidence was relevant because the prosecutor’s failure to disclose exculpatory evidence showed that the government knew that its case against appellant was weak. That proposed inference, however, was never fully explained to the trial judge. We need not decide, however, whether the claim was adequately preserved because, assuming, without deciding, that the trial court erred in excluding the evidence and precluding counsel from arguing its relevance to the jury, we conclude that the error was harmless.
We do not reverse convictions in order to punish prosecutors, see United States v. Hasting, 461 U.S. 499, 506-7, 103 S.Ct. 1974, 76 L.Ed.2d 96 (1983), but to remedy prejudice resulting from the trial court’s error in excluding evidence of the prosecutor’s nondisclosure that was probative of the questions that were presented to the jury for decision.
Here, even if the court had allowed evidence of the government’s Brady violation to come in, and defense counsel had argued to the jury that the government withheld the evidence because it thought its case was weak, we can conclude, “with fair assurance, after pondering all that happened without stripping the erroneous action from the whole, that the judgment was not substantially swayed by the error. ...” Kotteakos v. United States, 328 U.S. 750, 765, 66 S.Ct. 1239, 90 L.Ed. 1557 (1946). Although appellant was unable to present evidence that at the first trial the government had failed to disclose Boyd’s interview with Officer Woodward, and to argue to the jury that the government had done so because it considered that the revelation would seriously undermine the prosecution, the fact remains that by the close of the second trial, the jury was presented with the substantive evidence that Boyd had initially failed to identify appellant at the hospital. Ultimately, the jury rejected that evidence as not disposi-tive on the issue of identification. It is not difficult to see why. Boyd’s statement at the hospital was recounted in Officer Woodward’s testimony, which, due to its ambiguity, did not have much force:
Defense Counsel: Did [Boyd] tell you I don’t know who shot me ... ?
Officer Woodward: I’m not sure of his exact words, if he said I don’t know or I didn’t see or all’s I saw was a dark *223colored, someone shoot at me from a dark-colored car.
Although Officer Woodward later testified that Boyd did not mention appellant of his own accord, and it appears that Boyd did not accuse appellant even after the officer prompted him about the earlier “beef’ appellant had with Boyd, the context in which this interview took place reasonably could have persuaded the jury that it was understandable that Boyd did not tell the whole story at that time. Officer Woodward interviewed Boyd less than an hour after he had sustained several serious bullet wounds.15 To Officer Woodward, Boyd appeared “to be in pain, scared, kind of unsure of what was going to happen to him.” Boyd testified that he did not remember what he told Officer Woodward because he was “dizzy, probably drugged ... had a lot of drugs ... wasn’t very conscious of what was going on at the moment.” But when Boyd had fully regained consciousness after surgery, he was then able to tell Detective Francis that appellant was the shooter. Due to Boyd’s vulnerable physical and mental state at the time Officer Woodward interviewed him, the jury appears to have simply dismissed as relatively unimportant his initial failure to identify appellant. Moreover, Durham, who knew appellant from the neighborhood and was not significantly impeached, saw the shooting and identified appellant as the shooter. Therefore, it is difficult to conceive that it would have made much difference to the jury if it had known that the prosecutor in the first trial thought that Boyd’s exculpatory statement at the hospital undercut the government’s case, and for that reason failed to make a timely disclosure.16
B. Vouching
Appellant contends that the trial court improperly permitted the government to use what he characterizes as “self-vouching” statements about the government’s good faith in investigating the crime. The statements that appellant characterizes as “self-vouching” were posed during the prosecutor’s cross-examination of Sharia Shelton, appellant’s wife. In one question, for example, the prosecutor asked Mrs. Shelton whether the AUSA who prosecuted the first trial had asked her if she had “any information that would help your husband; isn’t that right?”17 Defense counsel objected to the question as eliciting hearsay. The trial court disagreed, saying that “[fit’s definitely not being admitted for the truth asserted, it’s ... coming in ... to show bias.” Defense counsel then asked for “an instruction that this is not to come in as being the truth.” *224The trial court denied the request, saying “I haven’t heard anything if it’s true yet.”
Appellant’s argument that the statements implicit in the cross-examination interrogation were “self-vouching” is made for the first time on appeal. We therefore review this claim for plain error. We hold that the trial judge did not have an obligation to strike the prosecutor’s questions sua sponte, or to give a limiting instruction restricting their use by the jury, as the questions merely sought to establish bias — that the witness had previously declined to relay allegedly exculpatory information to the government, even when she was invited to do so.
For the foregoing reasons, we affirm appellant’s convictions. We agree with appellant (and the government concedes) that because the two convictions of possession of a firearm during a crime of violence arose from the “single violent act” of shooting Boyd, one count must be vacated. See Nixon v. United States, 730 A.2d 145, 153 (D.C.1999), cert. denied 528 U.S. 899, 120 S.Ct. 233, 145 L.Ed.2d 196 (1999). For that sole purpose, we remand the case to the trial court.
So ordered.
. D.C.Code §§ 22-401, -4502 (2001).
. D.C.Code §§ 22-404.01, -4502 (2001).
. D.C.Code § 22-4504(b) (2001).
. D.C.Code § 22-4504(a) (2001).
. D.C.Code § 22-303 (2001).
. The first trial, held in March 2002, ended in a mistrial because the jury was unable to reach a unanimous verdict. Judge Weisberg presided over the first trial as well.
.Boyd had been seated in the driver’s seat of his car, which had tinted windows that were rolled up. He testified that he had been looking backwards over his left shoulder when the car carrying appellant approached. Boyd saw appellant's face as appellant reached out of the front passenger-side window of the blue Toyota, holding his two arms together, fully extended. Boyd stated that he was certain appellant was the shooter. Although Boyd admitted that he drank a “small portion” of vodka en route to Melon Street, he was confident that he was not intoxicated or "tipsy” and that the drink had not impaired his ability to perceive the identity of the shooter.
. Appellant was about two feet away from Boyd when he fired the shots.
. Durham testified that at first he could not see the shooter’s face because he was then looking through the tinted windows of both cars. Once the shooter’s car stared to pull away, Durham had a better view and was able to see the shooter’s "whole face” and his arm from the elbow down. Durham identified appellant in court as the shooter.
. Ferguson stated that she and her brother, Derrick Ferguson, were "like family” to Boyd. She was sixteen years old at the time of the shooting.
. It is unclear how Officer Woodward knew about the fight between Derrick Ferguson and appellant. At oral argument, the government represented to the court that the officer might have obtained such information through contacts developed through the Metropolitan Police Department's community policing.
. Brady v. Maryland, 373 U.S. 83, 83 S.Ct. 1194, 10 L.Ed.2d 215 (1963). In Brady, the Supreme Court held that "the suppression by the prosecution of evidence favorable to an accused ... violates due process where the evidence is material either to guilt or to punishment, irrespective of the good faith or bad faith of the prosecution.” Id. at 87, 83 S.Ct. 1194.
. The ex parte bench conference between the prosecutor and the trial judge was not transcribed, because the recording was "indiscernible.” Appellant’s counsel asked the government and the court to try to reconstruct the bench conference for purposes of appeal. These efforts were unsuccessful. Neither the judge nor the prosecutor remembered what had transpired.
. The day before the second trial was set to start, the prosecutor informed defense counsel about Officer Woodward’s interview with Boyd. Defense counsel then interviewed Officer Woodward.
. Boyd testified that he "couldn't move [his] arm,” and that his “lung collapsed, [and he] had to get a blood transfusion.” He later learned at the hospital that he "had nerve damage” because "[t]he bullet [had] bounced off [his] spine....”
. To the extent we take into account that there was a hung jury in the first trial, we cannot attribute it to doubt about Boyd’s identification of appellant as the shooter, as that jury was not informed that Boyd did not identify appellant as the shooter when he was first interviewed at the hospital.
. At another point the prosecutor asked:
Prosecutor: In fact, [the first prosecutor] told you that the last thing he wanted to do was to have the wrong person in jail; isn’t that right?
Mrs. Shelton: He told me that but I didn't believe him, and especially don’t believe him now since I found out that it is information that he withheld from my husband’s lawyer that could have dismissed him and had him brought back home almost two years ago, like 15 months ago.
Prosecutor: Did you — ■
The Court: Ladies and gentlemen, disregard that last answer, it wasn’t responsive.