ALBERT V. BRYAN, Senior Circuit Judge:
In United States v. MacDonald,-U.S. -, 102 S.Ct. 1497, 71 L.Ed.2d 696 (1982), the Supreme Court reversed our holding1 that appellant’s Sixth Amendment right to a speedy trial was abridged by the Government’s delay in obtaining the indictment. On remand, we now speak to MacDonald’s remaining advancements of error. See id. at - n.4, 102 S.Ct. at 1500 n.4. Since the Supreme Court’s opinion scrupulously chronicles both the facts of record and the protracted history of the case, see id. at -, 102 S.Ct. at 1499-1500, we forego repetitious narration.
I. Due Process
Our first concern is the accused’s grievance that the two-year interval between the termination of the military proceedings and the grand jury’s convocation 2 amounted to a denial of constitutionally-guaranteed due process. Laggardness in prosecuting a criminal charge rightfully exposes the Government to censure. Still, not every delay is of Constitutional moment. Indeed, we conclude that the instant hiatus, although objectionable, falls short of Constitutional injury.
To maintain this challenge, MacDonald must initially identify prejudice ascribable to the two-year gap. While a Sixth Amendment violation is made out merely by showing the potential for prejudice, here, under the Fifth Amendment, one must demonstrate actual prejudice. United States v. Lovasco, 431 U.S. 783, 789, 97 S.Ct. 2044, 2048, 52 L.Ed.2d 752 (1977); United States v. Marion, 404 U.S. 307, 325, 92 S.Ct. [227]*227455, 466, 30 L.Ed.2d 468 (1971). We need not explore MacDonald’s claims of actual prejudice, however, unless we also are assured that the delay “violates those ‘fundamental conceptions of justice which lie at the base of our civil and political institutions,’ and which define the community’s sense of fair play and decency.” 431 U.S. at 790, 97 S.Ct. at 2048 (citations omitted).
In this regard, we write mindful of Supreme Court guidance peculiarly applicable here. While it did not decide this question, six Justices commented on the nature of and reasons for the delay in indicting MacDonald. For the Court, Chief Justice Burger concluded:
Plainly the indictment of an accused— perhaps even more so the indictment of a physician — for the heinous and brutal murder of his pregnant wife and two small children is not a matter to be hastily arrived at either by the prosecution authorities or by a grand jury. The devastating consequences to an accused person from the very fact of such an indictment is a matter which responsible prosecutors must weigh carefully. The care obviously given the matter by the Justice Department is certainly not any indication of bad faith or deliberate delay.
- U.S. at - n.12, 102 S.Ct. at 1503 n.12. See also id. at-, 102 S.Ct. at 1503 (Stevens, J., concurring). We think this conclusive of the Lovasco test and fatal to the appellant’s Fifth Amendment argument.3
II. Psychiatric Character Testimony
MacDonald presses, too, that the trial court was at fault in rejecting tendered expert psychiatric character testimony. See Fed.R.Evid. 404(a)(1). After presenting thirteen lay witnesses who vouched for his nonviolent nature, MacDonald sought to present as evidence the conclusions of Dr. Robert L. Sadoff, a forensic psychiatrist, who would opine that the defendant was possessed of “a personality configuration inconsistent with the outrageous and senseless murders of [his] family.”4 See Fed.R. Evid. 404(a)(1). The trial judge, however, declined to permit the witness to testify, ruling
that irrespective of the admissibility of the proffered evidence under Rules 404 and 405. F.R.E., the probative value of the evidence was substantially outweighed by the danger of unfair prejudice, confusion of the issues and misleading the jury ....
485 F.Supp, 1087 at 1096-97; see Fed.R. Evid. 403. MacDonald now challenges this decision.
At the outset, we must recall that the appraisal of the probative and prejudicial value of evidence under Rule 403 is entrusted to the sound discretion of the trial judge; absent extraordinary circum[228]*228stances, the Courts of Appeal will not intervene in its resolution. E.g., Salem v. United States Lines Co., 370 U.S. 31, 35, 82 S.Ct. 1119, 1122, 8 L.Ed.2d 313 (1962) (exclusion of expert testimony to be sustained “unless manifestly erroneous”); United States v. Masters, 622 F.2d 83, 87-88 (4th Cir. 1980) (reversed only if decision is rendered “arbitrarily or irrationally”). The District Judge was keenly aware of the factors bearing on the wisdom of admitting Dr. Sadoff’s testimony and painstakingly examined each. Militating against admissibility were the cumulative nature of this testimony,5 and the certainty of fostering a “battle of the experts” over Dr. MacDonald’s psychiatric composition.6 The Court concluded that an expansion of the inquiry into this uncertain area would more likely confuse, rather than assist, the jury. A fair reading of the record and the District Court’s memorandum opinion belies any claim that this decision abused the discretion reposed in the trial court, and we refuse, as we must, the invitation to substitute our judgment for its.7
III. Pajama Top Demonstration
We next analyze appellant’s contention that the trial court erred in allowing the Government to demonstrate the similarity between the pattern of puncture holes in his pajama top and the pattern of icepick wounds in his wife’s chest. The top was found draped over Mrs. MacDonald’s chest when the authorities first arrived at the crime scene; 8 it was soaked with the victim’s blood and, among other breaks in the fabric,9 contained 48 round punctures. MacDonald has insisted that the shirt was damaged when, after it was pulled over his head in a scuffle and became entangled about his hands, he used it to fend off blows from an icepick wielded by the same assailants he avers murdered his family. According to his version of the incident, he placed the nightshirt on his wife’s chest when he regained consciousness and discovered her body.
Suspicious of this story, the prosecution theorized that he intentionally placed the pajama top on his wife’s body to disguise the fact that her blood had stained it in his fatal attack on her. Consistent with this hypothesis and the defendant's alleged maiming of the bodies to give the appearance of a massacre, the Government postu[229]*229lated that he riddled his wife’s body with an icepick after laying the shirt across her body. Laboratory experts were asked to fold the shirt in the same manner as it was found at the MacDonald home and to determine whether the pattern of holes in the shirt and in the body coincided. Acting on these directions, the investigators folded the right sleeve inside out10 and, after some adjustment, aligned the 48 holes so that a pattern of 21 punctures emerged. The resulting array, 5 holes on the right side and 16 on the left, bore a striking resemblance to the pattern of icepick wounds suffered by Mrs. MacDonald.
The defense contends that allowing the jury to view this exhibition was error, urging that the prejudicial impact of this demonstration far outweighed its probative value. See Fed.R.Evid. 403. Further, counsel poses the possibility that the shirt was moved before it was photographed at the crime scene, the potentially infinite ways to align the 48 holes into a pattern of 21, and a variety of plausible shortcomings in the methods employed by the Government investigators. Each of these points merits scrutiny, and each was advanced, without limitation, before the jury.
Our task, however, is not to decide this dispute. As with the District Court’s refusal to admit expert psychiatric testimony on the issue of Dr. MacDonald’s personality, our inquiry now is, baldly, only whether that Court abused its discretion by finding this demonstration more probative than prejudicial. See part II supra. We think the District Court’s decision that this evidence was not unduly prejudicial was acceptable. See United States v. Bailer, 519 F.2d 463, 466 (4th Cir.), cert. denied, 423 U.S. 1019, 96 S.Ct. 456, 46 L.Ed.2d 391 (1975). We therefore do not think its ruling was an abuse of discretion.11
IV. The Rock Report
Next, MacDonald argues the District Court erred when it refused to allow into evidence the findings and conclusions of Colonel Warren V. Rock, the investigating officer designated by the Army in 1970 to determine whether probable cause existed to prosecute MacDonald.12 Principally, MacDonald argues the report was admissible as a public record under Fed.R.Evid. 803(8)(C).
Under Article 32 of the Uniform Code of Military Justice, an accused has a right to a pre-court martial investigation. An impartial officer is charged with assembling the evidence, ascertaining what charges may be brought, whether the charges are true, and what disposition should be made of the accusations in the interest of justice and discipline. See 10 U.S.C. § 832(a) (1976). While this probe is purely advisory, the subject is furnished counsel with the right to cross-examine witnesses. The officer then must forward a report to the appropriate military authorities. Id.
MacDonald contends that these attributes place the Rock report squarely within Rule 803(8)(C). Under this rule, public records, reports, or statements of factual findings, although hearsay, are admissible against the Government in a criminal case if “resulting from an investigation, made pursuant to authority granted by law, unless the sources of information or other circumstances indicate lack of trustworthiness.” [230]*230The Government attacks its admissibility, pressing first that it was not trustworthy because in the years after 1970, a more detailed and sophisticated examination of physical and other proof was possible and second, that even if literally acceptable, the District Court had discretion, which it properly exercised, to exclude the proffer on grounds of irrelevance, prejudice, or confusion.
Although Rule 803(8)(C) apparently has never been construed in this context, we think it apparent that the Rock report met the facial standards of admissibility. It was a) a “public record,” b) to be introduced against the Government in a criminal case, c) containing factual findings, d) made pursuant to an investigation mandated by law, e) containing, given the impartiality of the investigating officer, the availability of counsel, and the right to examine and cross-examine, adequate circumstantial assurances of trustworthiness. This conclusion only begins our inquiry, however, because Rule 803 does not mandate admission, it only allows reception of qualifying evidence.
In Cox v. Babcock E. Wilcox Co., 471 F.2d 13 (4th Cir. 1972), we indicated that the admission of evaluative public records was discretionary with the trial court. Citing the dissent from the denial of rehearing in Smith v. Universal Services, Inc., 454 F.2d 154, 160 (Dyer, J., dissenting), we said that a trial judge’s decision to reject an EEOC investigative report was unassailable. As Smith made clear, such reports at times suffer from an undue risk of prejudice. To the extent they contain credibility determinations, they tend to undermine the exclusive province of the jury.
Such reasoning upholds the presiding judge’s disallowance of Colonel Rock’s findings and conclusions. While the Court properly could have admitted the evidence, we do not question the ruling of declination. The ultimate query to the jury in this case was whether defendant committed the crimes charged. Nowhere has appellant shown that this report would have helped towards an answer to this question. Indeed, its admission would have tended to perplex, in that it likely would have distracted the jury’s attention from its task of ascertaining guilt or innocence to a second-guessing of the Government’s conduct of the murder investigation. There is no question that MacDonald was free to call any witnesses who testified in the Article 32 investigation or, indeed, to use such testimony, as appropriate, at his trial. Under these circumstances, we think the District Court sensitively concluded that the Rock report should be excluded. Seeing no abuse of discretion, we reject this assignment of error.
V. The Stoeckley Witnesses
Finally, appellant lays fault to the District Court’s exercise of discretion in excluding the testimony of seven witnesses, all of whom would have testified to various inculpatory comments or statements assertedly made by Helena Stoeckley. The exclusion of this evidence, charges MacDonald, was error in that it abridged appellant’s Fifth Amendment right to call witnesses in his own defense, was admissible under Rule 804(b)(3) and, in any event, constituted proper impeachment of Stoeckley’s own testimony. Reviewing the evidence in question, we analyze these contentions in turn.
A
Since the commission of the crimes in February 1970, MacDonald has maintained that he and his family all were victims of a bizarre cult attack. He claims that the perpetrators included three men and a woman wearing a floppy hat, having blond hair, and wearing boots. The woman, he says, was Helena Stoeckley.
At trial, Stoeckley testified that although her hair was brown in color, she owned a blond wig at the time of the crimes. She further said that she owned a floppy hat and boots. Although her recollection of events on the evening of February 16 and during the early morning hours of February 17 was, at best, hazy, she recalls not wearing the blond wig. However, she admitted to burning the wig and discarding the boots two days later.
[231]*231While Stoeckley offered this much evidence seeming to corroborate MacDonald’s version of the killings, the remainder of her testimony either contradicted him or tended to undercut his narration of the events. For example, she testified that she had never seen MacDonald before trial, had never been in his Fayetteville apartment, and while she vaguely felt that she might have had some connection with the crimes, since she had no explanation of her whereabouts between midnight and 5:30 a. m., she insisted she was not present at their commission. In all, the evidence disclosed that Stoeckley’s memory was exceedingly poor and that she was constantly under the influence of narcotic drugs.
Because of this faulty memory, appellant sought to introduce a series of inculpatory statements through other witnesses. In this proffer to the District Court, in the absence of the jury, it was shown that these witnesses would give evidence substantially as follows:
1) Robert A. Brisentine, an Army investigator assigned to the homicides, interviewed Stoeckley April 23 and 24, 1971, approximately 14 months after the crime. Stoeckley told him she was present during the murders, but did not think that she had taken part. She offered to divulge the participants and provide more details, but wanted immunity from prosecution. Subsequently, she said she had “said too much.”
2) James Gaddis, an officer of the Nashville Police Department, revealed that Stoeckley had confessed her belief that she was involved in the crimes in the fall of 1970. She also said that she knew others who were involved.
3) P. E. Beasley, a former detective with the Fayetteville Police Department, explained that Stoeckley had been a reliable drug informant for several years prior to the murders. On the morning of February 18,1970, a day after the fateful events, she told Beasley, in response to his accusation that she matched MacDonald’s description of the female intruder, “[i]n my mind, it seems I saw this thing happen ... I was heavy on mescaline.” Beasley also said that he observed funeral wreaths in the yard of Stoeckley’s home. He added that she had told him she was mourning the MacDonalds.
4) Jane Zillioux, a Nashville neighbor of Stoeckley throughout the fall of 1970, said that Stoeckley had confided to her that she could not return to Fayetteville because she was involved in murders there. She further confessed that the victims were a woman and two small children and that she had disposed of the clothes she had been wearing to sever her connection with the crimes.
5) Charles Underhill, another Nashville acquaintance, testified that Stoeckley told him “they killed her and the two children.”
6) William Posey, a neighbor of Stoeckley in Fayetteville, testified that Stoeckley told him a few days after the slayings that she didn’t kill anyone herself, but did hold a light while the crime was in progress. She also confided to him that she -was spotted by a policeman leaving the house.
7) Wendy Rouder, one of MacDonald’s lawyers, testified that two days after Stoeckley had testified she could not remember anything about the night of the crime, she told Rouder “I still think I could have been there that night.” Stoeckley also feared she would not be able to live with the guilt if MacDonald were convicted. Finally, she recalled standing by the couch in the MacDonald apartment holding a candle “only — you know — it wasn’t dripping wax; it was dripping blood.”
After all of these individuals had testified without the presence of the jury, the District Court excluded the evidence. It ruled the statements inadmissible hearsay because untrustworthy. In addition, the Court rejected MacDonald’s attempt to use the statements as impeachment on the grounds that it was not impeachment, properly so called, and in any event, was excludible under Rule 403 as unduly confusing and prejudicial.
B
Relying on Chambers v. Mississippi, 410 U.S. 284, 93 S.Ct. 1038, 35 L.Ed.2d 297 [232]*232(1973), MacDonald complains that the exclusion of the testimony of these seven “Stoeckley witnesses” deprived him of due process. He also maintains that Fed.R. Evid. 804(b)(3) explicitly supplies an exception to the hearsay rule and authorized admission of the Stoeckley witnesses’ testimony.
Chambers involved an appeal of a criminal conviction obtained after the refusal of the trial court to permit defendant to introduce the testimony of three witnesses who would have said that one Gable MacDonald admitted to each witness that he was guilty of the murder charged to Chambers. The Mississippi courts excluded the testimony on the ground that it was hearsay and not admissible under any exception recognized in that State. Particularly, Mississippi did not recognize statements against one’s penal interest as an exception to the general hearsay prohibition.
The Supreme Court reasoned that enforcement of this hearsay rule denied Chambers’ due process. In so concluding, it found sufficient indications of trustworthiness in the circumstances of McDonald’s admissions. For example, the evidence disclosed that each of the three witnesses was a close associate of McDonald and that McDonald had made the damaging remarks spontaneously. In addition, they were corroborated by other facts — a sworn (although subsequently repudiated) confession by McDonald, testimony of an eyewitness putting McDonald at the crime scene, proof that McDonald owned a gun similar to the weapon used, and evidence that he was seen with the gun just after the shooting — giving credence to the asserted veracity of the hearsay. Finally, the Court noted that McDonald was present and available for the prosecution to call to the stand if it so chose. In circumstances “where constitutional rights directly affecting the ascertainment of guilt are implicated, the hearsay rule may not be applied mechanistically to defeat the ends of justice.” Id. at 302, 93 S.Ct. at 1049.
This ruling, in large measure, is codified for Federal Courts in Fed.R.Evid. 804(b)(3).13 It conditions admissibility on the unavailability of the declarant, and provides that a statement of the declarant is admissible if
at the time of its making [it was] so far contrary to the declarant’s pecuniary or proprietary interest, or so far tended to subject him to civil or criminal liability, or to render invalid a claim by him against another, that a reasonable man in his position would not have made the statement unless he believed it to be true. A statement tending to expose the declarant to criminal liability and offered to exculpate the accused is not admissible unless corroborating circumstances clearly indicate the trustworthiness of the statement.
Fed.R.Evid. 804(b)(3). Thus, as applied to criminal matters, three requisites must be met prior to reception of the hearsay testimony. First, the declarant must be unavailable. Second, from the perspective of the average, reasonable person, the statement must have been truly adverse to the declarant’s penal interest, considering when it was made. Cf. United States v. Evans, 635 F.2d 1124 (4th Cir. 1980), cert. denied, 452 U.S. 943, 101 S.Ct. 3090, 69 L.Ed.2d 958 (1981) (suggesting that statement is not against penal interest where declarant made statements which appeared to subject [233]*233himself to criminal liability but which actually would constitute defense to more serious crime). Finally, corroborating circumstances must clearly establish the trustworthiness of the statement. United States v. Satterfield, 572 F.2d 687 (9th Cir.), cert. denied, 439 U.S. 840, 99 S.Ct. 128, 58 L.Ed.2d 138 (1978).
We have no difficulty in agreeing with appellant that declarant Stoeckley was unavailable 14 and that her statements, if true, clearly would be against her penal interest. The question remains, however, whether the “corroborating circumstances clearly indicate the trustworthiness of the statement[s].”
As corroborating circumstances, MacDonald adverts to the fact that Stoeckley owned and regularly wore boots, a blond wig, and a floppy hat, thus permitting her to fit the description of the female assailant described by defendant. In addition, defendant argues that Stoeckley had no motive to fabricate; that each admission was consistent with the others; that, for the most part, her declarations were spontaneous and to close associates; that at the time of their making, she was (and is) still subject to criminal liability, and in making these statements, she recognized this fact; that she cannot account for her whereabouts on the night of the crime; and that her mourning the deaths evinces a consciousness of guilt. The District Court, by contrast, concluded the declarations were untrustworthy because Stoeckley’s pattern of remarks in admitting and denying complicity rendered her hopelessly unreliable, and because her pervasive involvement with narcotic drugs, and her admissions that she was under the virtually continual influence of the drugs when these statements were made further manifested unreliability.
As with other of these evidentiary objections, our role in reviewing decisions at nisi prius construing Rule 804(b)(3) is a limited one. We must uphold the trial court unless it has abused its discretion. See United States v. Guillette, 547 F.2d 743 (2d Cir. 1976). No such abuse is evident here.
It is to be recalled that Rule 804(b)(3) places upon the proponent of a statement against interest a formidable burden. The declaration offered to exculpate the accused must be supported by corroborating circumstances that “clearly indicate the trustworthiness of the statement.” (emphasis added). Cf. Fed.R.Evid. 804(b)(5) (residual exception only requires “equivalent circumstantial guarantee of trustworthiness”). As the Advisory Committee’s Notes on this provision instruct, the risk of fabrication in this setting is significant. Consequently, rather than permitting only the jury to decide what weight to give the evidence, the initial responsibility is vested in the District Court. It is admonished that “[t]he requirement of corroboration should be construed in a manner [so] as to effectuate its purpose of circumventing fabrication.” See Advisory Committee’s Notes to Rule 803, reprinted in Federal Rules Pamphlet, Criminal at 222 (West 1981).
At bottom, the sticking point here, as recognized by the District Court, is the fundamental problem of trustworthiness. While MacDonald is able to point to a number of corroborating circumstances, he does not demonstrate, finally, that they make Stoeckley’s alleged declaration trustworthy. Her apparent longstanding drug habits made her an inherently unreliable witness. Moreover, her vacillation about whether or not she remembered anything at all about the night of crime lends force to the view that everything she has said and done in this regard was a product of her drug addiction. Given the declarant’s “pathetic” appearance, our conviction is that the District Court was not in error in adjudging that defendant failed to carry his burden under Rule 804(b)(3). Thus MacDonald’s argued violation of the Due Process clause fails.
C
Failing to establish the truth of the proffered Stoeckley declarations, MacDonald [234]*234endeavored to use this same testimony as impeachment of Stoeckley’s own testimony. The trial judge rejected the attempt, but on alternative grounds. To begin with, he explained that the testimony was unduly confusing and not proper as impeachment since its substance already had been ruled inadmissible for its truth. Second, the Court concluded that the evidence to be offered by the Stoeckley witnesses did not contradict Stoeckley’s own sworn testimony. Rather, it merely tended to supplement her statements.
The Court, we believe, properly used Rule 403 to exclude such testimony. As we observed in United States v. Morlang, 531 F.2d 183 (4th Cir. 1975), there is a significant danger of prejudice where evidence is adduced for impeachment purposes that could not be presented directly on the merits of the case. Id. at 190. Of course, as defendant rightly notes, Fed.R.Evid. 607 permits a party to impeach its own witness. Still, where as here, the jury is likely to be confounded by statements which Stoeckley repeatedly avowed under oath she did not remember making, the District Court properly can exclude them under Rule 403.
VI
At end, MacDonald asserts that the evidence, even when taken most favorably for the prosecution, does not justify the finding of guilt beyond a reasonable doubt. See Glasser v. United States, 315 U.S. 60, 62 S.Ct. 457, 86 L.Ed. 680 (1942). Our canvass of the record, however, gives ample warrant for the verdict. With no merit in any issue on this appeal, the judgment of conviction is affirmed.
Affirmed.