Calvin W. West, Floyd Lee Davis and Joseph Lee Dempsey appeal their convictions for distributing heroin and possessing heroin with the intent to distribute it. The most significant question presented is whether the admission of the grand jury testimony of Michael Victor Brown, who was slain prior to trial, was permissible under Rule 804(b)(5) of the Federal Rules of Evidence and the Confrontation Clause of the Sixth Amendment. We hold that it was.
The convictions challenged here are the product of an extensive Drug Enforcement Agency (DEA) investigation in which Brown played a vital role. Brown volunteered his assistance to the DEA while he was in jail on a drug charge and under a detainer for parole violation. He agreed to purchase heroin under police surveillance.
Each purchase was similar. Brown would contact West or Davis and arrange to purchase heroin. Twice the DEA monitored Brown’s calls to West arranging heroin deals. It also monitored one phone call to Davis. On other occasions it seems that Brown simply notified the DEA that he had arranged a purchase.
Each time that the DEA agents received notice that Brown was about to make a purchase, they made arrangements for extensive surveillance. Before each purchase, DEA agents strip-searched Brown to make sure that he had no drugs, and they concealed a transmitter on him. They then searched his vehicle to be sure that it contained no drugs and gave Brown the money required for the anticipated purchase.
According to the government’s evidence, on three occasions, Brown went to West, gave West money, and obtained heroin. Twice Brown went to Davis, gave Davis money and obtained heroin. On another occasion, Brown gave West money then accompanied him to meet Dempsey. West then gave Dempsey money and told Brown that they were to meet Dempsey at Griffin’s home. Brown and West went to Griffin’s home. Dempsey arrived, went to the open window of Brown’s car and then entered Griffin’s home and told Brown that everything was all right. Brown then returned to his car to find 30 capsules of heroin.
Each time, law enforcement officials observed Brown’s movements and obtained photographs of Brown as he met with West and with Davis. After each transaction Brown returned to the DEA office and surrendered the heroin that he had purchased and any money remaining. Each time the agents searched Brown and his car to be sure that he retained no contraband. Agent Scott then discussed with Brown the events that had taken place and composed a detailed summary of what had occurred, which Brown read, corrected and signed. After one of the purchases Brown himself prepared a statement which Agent Scott revised before Brown read, corrected and signed it. Each time, Scott and Brown listened to the tapes from the body transmitter for audibility and voice identification. By reviewing the tapes with Brown, Scott independently became able to identify the voices of the defendants.
On March 8, 1976, the defendants and others were indicted by a grand jury, apparently without Brown’s testimony. On *1134March 16, Brown appeared before a grand jury and testified under oath regarding his knowledge of the drug traffic in Virginia’s Tidewater area. The government attorney read the statements that Brown had signed and periodically asked Brown if they were correct.
As a result of his cooperation, Brown was released from jail, the pending drug charge against him was nol prossed, and the de-tainer for parole violation was lifted. The DEA also gave Brown $855 for his personal use so that he would not arouse suspicion and jeopardize his cover by being without funds immediately after supposedly selling a large amount of heroin.
On March 19 Brown was murdered in a manner suggestive of contract killers. Four bullets were fired into the back of his head while he was driving his car. According to the government, at least four potential government witnesses in this and related narcotics investigations have been murdered after they had agreed to cooperate. But these defendants have not been charged with Brown’s murder, and the government did not offer any evidence to show that they were responsible for it.
On April 22, a week before the scheduled trial date, the government notified the defendants, pursuant to Rule 804(b)(5) of the Federal Rules of Evidence, that it intended to introduce Brown’s grand jury testimony at trial. It agreed to give defense counsel all of its evidence, including Brown’s arrest record, and transcripts of the tapes of Brown’s conversations with the defendants.
After a pre-trial hearing, the district court ruled that the grand jury testimony was admissible under Rule 804(b)(5) because, under the circumstances, it was essential and trustworthy. It also gave the defense a week’s continuance after it announced that it would admit Brown’s grand jury testimony.
During the trial the government introduced the transcript of Brown’s grand jury testimony, the photographs, an expert on voice identification and the heroin. It also played the tapes of Brown’s conversations with the defendants. Law enforcement agents testified about their observation of Brown’s activities and corroborated Brown’s highly detailed grand jury testimony. The government sought to introduce transcripts which it had prepared from the tapes from Brown’s body transmitter. Although the district judge found that the transcripts were a fair representation of the taped conversations, he permitted the jury to see the transcripts only while they listened to the tapes and instructed the jurors to decide for themselves what the tapes said.
I.
The defendants contend that the district judge erred in concluding that the transcript of Brown’s grand jury testimony was admissible under Rule 804(b)(5).
Rule 804(b)(5) provides:
“(b) Hearsay exceptions. The following are not excluded by the hearsay rule if the declarant is unavailable as a witness:
******
“(5) Other exceptions. A statement not specifically covered by any of the foregoing exceptions but having equivalent circumstantial guarantees of trustworthiness, if the court determines that (A) the statement is offered as evidence of a material fact; (B) the statement is more probative on the point for which it is offered than any other evidence which the proponent can procure through reasonable efforts; and (C) the general purposes of these rules and the interests of justice will best be served by admission of the statement into evidence.”
The defendants do not contend that the grand jury transcript fails to meet the criteria of clauses (A), (B) and (C). Instead, they focus upon the general requirement that the statement have “equivalent circumstantial guarantees of trustworthiness” as statements the admission of which is authorized by any of the preceding four paragraphs. They find a lack of trustworthiness in Brown’s criminal record and their lack of any opportunity to cross-examine him. They point to legislative history indi-*1135eating that Rule 804(b)(5) applies only where “exceptional circumstances” lend to the extra-judicial statement a degree of trustworthiness equivalent to that of evidence admissible under other § 804(b) exceptions.1
There were present very exceptional circumstances providing substantial guarantees of trustworthiness of Brown’s grand jury testimony probably exceeding by far the substantial guarantees of trustworthiness of some of the other § 804(b) hearsay exceptions. Before each contact by Brown with West, Davis or Dempsey, the agents took elaborate steps to assure themselves that Brown possessed no drugs or money other than the money supplied by the agents to effect the purchases. Except when he entered a building and became concealed from their view he was under constant surveillance, and photographs were taken when he was with one of the defendants. Moreover, his transmitter was broadcasting his conversations with the defendants, and a tape recorder preserved those conversations. Moreover, immediately after each purchase, he and one of the agents reviewed what Brown had done, said and observed, and a statement of it was prepared and corrected. The immediate transcription and verification of Brown’s statements provide an additional guarantee other admissible hearsay statements lack.2 But the most impressive assurance of trustworthiness comes from the corroboration provided by the observations of the agents, the pictures they took and their recordings of the conversations. Brown had a criminal record, and he was seeking favors to avoid further incarceration, but the circumstances make deception of the agents inconceivable. The agents simply followed, photographed and recorded conversations to such an extent that deception by Brown was substantially impossible. Moreover, his interest in gaining favors to avoid further imprisonment gave him every incentive to be extremely accurate in his reports. He knew what the agents were doing to corroborate and verify his reports, and any attempted deception would only have been calculated to arouse the suspicion of the agents and to lose for Brown their favor.
The substantially contemporaneous sworn written statements by Brown were the basis of Brown’s grand jury testimony. The corroborative circumstances and verification procedures lend to his grand jury testimony a degree of trustworthiness probably substantially exceeding that inherent in dying declarations, statements against interest, and statements of personal or family history, all of which are routinely admitted under § 804(b)(2), (3) and (4).
Although Brown’s grand jury testimony was not subject to immediate cross-examination, to a large extent what Brown said was corroborated by the observations of the agents. The agents did appear as witnesses and were subject to cross-examination about what they observed, including the possibility of mistake or prevarication by Brown, and their own roles in preparing Brown’s statements. Moreover, defense counsel had Brown’s criminal record and knew of his interest in gaining favor with the agents. They could, and did, present those bases of impeachment of Brown which might have been developed on cross-examination if Brown had been present to testify.
Under all of these circumstances, the absence of an opportunity to cross-examine Brown himself is of considerable less signif*1136icance than in those cases involving statements against interest,- statements of family history, or dying declarations.
Whether the circumstantial guarantees of trustworthiness of Brown’s grand jury testimony are equivalent to those which arise from cross or direct examination which underlies the former testimony exception of § 804(b)(1), we need not determine. In this unusual case, those guarantees were probably greater, but the equivalent guarantee of trustworthiness requirement of § 804(b)(5) is met if there is equivalency of any one of the preceding § 804(b) exceptions. Clearly there is such equivalency with the exceptions we find in paragraphs 2, 3, and 4.
The defense lawyers were given every opportunity to attack Brown’s credibility, and they fully utilized their opportunities. It may be of passing significance that the jury did not accept all that Brown said, for it acquitted two of the defendants implicated by him. That it convicted West, Davis and Dempsey suggests that it carefully considered the very substantial extent to which the corroborative evidence established their guilt, either directly or through strong demonstration of the trustworthiness of Brown’s testimony as to them.
II.
The contention is earnestly advanced that even though Brown’s grand jury testimony meets the requirements of § 804(b)(5) of the Federal Rules of Evidence, its admission was barred by the Confrontation Clause of the Sixth Amendment. That Clause provides “In all criminal prosecutions, the accused shall enjoy the right . . . to be confronted with the witnesses against him.”
The Supreme Court has consistently held that the Confrontation Clause itself does more than to require that the prosecution produce available witnesses for live testimony. It affirmatively requires the exclusion of extra-judicial statements which have no badges of reliability. Thus, we are required to make a separate determination, focusing upon the Confrontation Clause itself, whether Brown’s grand jury testimony bore sufficient guarantees of reliability, Dutton v. Evans, 400 U.S. 74, 89, 91 S.Ct. 210, 27 L.Ed.2d 213 (1970), or whether the circumstances provided the jury with sufficient bases to judge its trustworthiness. California v. Green, 399 U.S. 149, 161, 90 S.Ct. 1930, 26 L.Ed.2d 489 (1970).
It has long been recognized that the Confrontation Clause does not preclude the admission in a criminal trial of all extra-judicial declarations. As long ago as 1892, the Supreme Court held in Mattox v. United States, 146 U.S. 140, 13 S.Ct. 50, 36 L.Ed. 917, that the Confrontation Clause does not require the exclusion in a criminal trial of a dying declaration, and it recognized that there are other analogous situations in which extra-judicial declarations might be allowable.3 More recently, statements against penal interest have been held admissible,4 and in California v. Green, 399 *1137U.S. 149, 90 S.Ct. 1930, 26 L.Ed.2d 489 (1970), the Supreme Court held that testimony at a preliminary hearing was admissible when the witness at trial suffered a loss of memory, since the preliminary hearing testimony had been subject to cross-examination. Testimony at an earlier trial of a witness unavailable at the time of the retrial is similarly admissible, Mancusi v. Stubbs, 408 U.S. 204, 92 S.Ct. 2308, 33 L.Ed.2d 293 (1972).
It is true that testimony of a witness at a preliminary hearing which was not at all subjected to cross-examination because the defendant had no lawyer present, constitutionally may not be admitted under the Confrontation Clause.5 The Confrontation Clause also requires the exclusion of a confession implicating the defendant given to police by a witness who invoked his privilege against self incrimination to avoid testifying at the trial.6 The confession was doubtless against the penal interest of the witness, but it was a confession given under potentially coercive circumstances which could not be adequately examined; they were not the spontaneous declarations made to friends and confederates which were held to be admissible under the Confrontation Clause in Dutton v. Evans.
The cases in the Supreme Court considering the application of the Confrontation Clause to the admission of previously recorded testimony have distinguished between testimony subject at the time to cross-examination and testimony which was not. When tested by cross-examination, the testimony gained some added measure of reliability and, even with a written record, the trier of fact is given some basis for judging the credibility of the testimony from the answers to the cross-examination. It is not as satisfactory as it is when the trier of fact can observe the demeanor of the witness, but evasive answers may still appear evasive on paper, and forthrightness can be evident in writing.
The Supreme Court has never intimated, however, that cross-examination is the only means by which prior recorded testimony may be qualified for admission under the Confrontation Clause. Just as surrounding circumstances may give assurance of reliability to dying declarations and to declarations against penal interest, so surrounding circumstances may give assurance of reliability to prior recorded testimony which was not subject at the time to cross-examination. They also may provide the trier of fact with firm bases for judging the credibility of the witness and the truthfulness of his testimony.7
Such circumstances are present in abundant measure here. We have canvassed them in considering the admissibility of the testimony under § 804(b)(5) of the Federal Rules of Evidence. The agents testified to their preparation of Brown for each contact with the defendants, to what *1138they observed during their surveillance, to their recordings of Brown’s conversations with the defendants and others, and the preparation of Brown’s written and signed statements immediately after each event. Moreover, the jury listened to the tapes as well as the written statements, and the agents at the trial were subject to cross-examination about their testimony concerning what they did and what they observed. All of this lends a high degree of reliability and trustworthiness to Brown’s testimony before the grand jury. It furnished the jury a firm basis for judging the truthfulness of what Brown said before the grand jury.
It should not be surprising that the same circumstances suffice to meet the requirements of § 804(b)(5) and of the Confrontation Clause. This is true of other exceptions to the hearsay rule which do not contravene the Confrontation Clause. The dying declaration and the declaration against penal interest have indicia of reliability which warrant their admission as exceptions to the hearsay rule while at the same time warranting their admission under the Confrontation Clause.
In the plurality opinion in Dutton, rejected hearsay declarations involved in earlier cases were characterized as “devastating” or “crucial”. This has led to the supposition that the principle of Dutton applies only when the declaration is neither crucial nor devastating, see, The Supreme Court, 1970 Term, 85 Harv.L.Rev. 3, 192, 196 (1971); at least, the standard of reliability should be elevated as the adverse impact of an extra-judicial declaration increases. We, however, find no basis for applying such a rule. If the admission of the declaration is harmless, no problem is presented, but faithfulness to the constitutional principle demands the exclusion of all extra-judicial declarations having no substantial indicia of reliability if admission of the declaration would have some tendency to persuade the jury to a finding of guilt. A flexible standard of more or less indicia of reliability triggered by suppositions about the force of the impact of the particular evidence upon the jury could hardly provide a workable standard. Here, the indicia of reliability are great, but we reject the notion that small indications of reliability will suffice if the prejudicial effect of the declaration is supposed to be not great while preserving a stricter standard'for the admission of declarations seemingly having a greater impact.
For these reasons, we find no error in the admission of Brown’s grand jury testimony.
III.
We find nothing meriting discussion in the remaining contentions.
The agent’s testimony that Brown had dialed West’s telephone number and the agent’s identification of West’s voice, which he learned to recognize from frequent review of the tapes, was sufficient authentication of the tape of October 30, 1975.
Nor did the trial judge abuse his discretion in permitting the jury to see transcripts of the taped conversations as the tapes were being played. The transcripts were fair, though the judge instructed the jurors to depend upon their own hearing of the tapes. United States v. Hall, 342 F.2d 849, 853 (4 Cir. 1965).
The evidence of the guilt of West and Davis was more than abundant; that of Dempsey’s guilt was quite adequate.
AFFIRMED.
. The defendants also rely upon United States v. Fiore, 443 F.2d 112 (2d Cir. 1971) in which it was held that grand jury testimony was inadmissible where the declarant was physically available but refused to take the oath and submit to meaningful cross-examination. Fiore is inapposite, for it was decided before the adoption of Rule 804(b)(5). Two cases decided after adoption of the rule have reached opposite results. Compare United States v. Carlson, 547 F.2d 1346 (8 Cir.) (admitting prior grand jury testimony under Rule 804(b)(5)) with United States v. Gonzalez, 559 F.2d 1271 (5th Cir. 1977) (testimony not admissible). Both courts focused for purposes of their analysis of the admissibility of the evidence under the F.R. Evid. on its reliability.
. See McCormick, Evidence, § 261 at 626 (2d Edition, 1972).
. Mattox at 151, 13 S.Ct. 50.
. Chambers v. Mississippi, 410 U.S. 284, 93 S.Ct. 1038, 35 L.Ed.2d 297 (1973); Dutton v. Evans, 400 U.S. 74, 91 S.Ct. 210, 27 L.Ed.2d 213 (1970). Though holding such declarations admissible, the Court, in Chambers v. Mississippi, was not concerned with the Confrontation Clause. At his trial, Chambers undertook to prove in his own defense that one McDonald, rather than he, fired the fatal shots. He sought to present McDonald as an adverse witness, but was prevented from doing so by an application of Mississippi’s witness voucher rule. He then-tendered three witnesses, close associates of McDonald’s, who would have testified that, shortly after the slaying, McDonald had made spontaneous statements to each of them, separately, strongly implicating himself as the slayer. The testimony was rejected, for, while Mississippi recognized as an exception to the hearsay rule a statement against pecuniary or proprietary interest, it did not recognize as such an exception a statement against penal interest. The Supreme Court examined the indicia of trustworthiness surrounding these statements. These included their spontaneity, the fact that each was made in seeming confidence to a close associate, the fact that each tended to corroborate the other, the fact that there was an eyewitness to testify that McDonald fired the fatal shots, and the. fact that McDonald was known to have owned a revolver similar to the one employed in the shooting. The conclusion was that the three declarations were shown to have been of sufficient trust*1137worthiness that they were not only admissible, but their rejection was a denial of Chambers’ due process right to a fair trial. The rejection of the testimony of those witnesses, coupled with the state’s refusal to permit Chambers to cross-examine McDonald, who had repudiated a formal confession and asserted an alibi, resulted in the reversal of Chambers’ conviction for want of a fair trial.
. Pointer v. Texas, 380 U.S. 400, 85 S.Ct. 1065, 13 L.Ed.2d 923 (1965). See Barber v. Page, 390 U.S. 719, 88 S.Ct. 1318, 20 L.Ed.2d 255 (1968).
. Douglas v. Alabama, 380 U.S. 415, 85 S.Ct. 1074, 13 L.Ed.2d 934 (1965).
. Compare United States v. Rogers, 549 F.2d 490, 500 (8th Cir. 1976) (prior testimony of witness with memory lapse had sufficient indi-cia of reliability so that Confrontation Clause was not violated by admission) with U. S. v. Gonzalez, 559 F.2d 1271 (5th Cir. 1977) (grand jury testimony lacked surrounding indicia of reliability so that admission violated Confrontation Clause). Both the Rogers and Gonzalez courts acknowledged that the reliability of hearsay evidence in part determines whether admission of the evidence violates the Confrontation Clause. Each case must be examined on its own facts. We do not hold that all hearsay admissible under the 804(b)(5) exception to the rule against hearsay can be admitted without violation of the Confrontation Clause rights of a defendant. We hold only that analysis under both Rule 804(b)(5) and under the Confrontation Clause must begin by focusing on the reliability and trustworthiness of the challenged statement.