Appellant Wyler was convicted with nine other defendants after a jury trial in the Eastern District of New York (Mishler, Ch.J.) of conspiracy to violate the narcotics laws. 21 U.S.C. §§ 173 and 174. On July 8, 1971, Wyler was sentenced to ten years in prison, consecutive to a New York State sentence he was then serving. Thereafter, Wyler and the other nine defendants appealed to this court, with the result that their convictions were affirmed. United States v. Vega et al., 458 F.2d 1234 (1972). Notwithstanding this affirmance of his conviction, this court thereafter, on July 12, 1972, ordered Wyler’s appeal “reinstated” because of his post-affirmance claim of a conflict of interest possessed by the lawyer then representing him on appeal and who had been trial counsel for a co-defendant, Vega. A different panel of this court now having heard Wyler’s reinstated appeal, we once again affirm the conviction.
In light of the previous opinions of this court, United States v. Vega, supra; see also United States v. Nathan, 476 F. 2d 456, decided March 16, 1973, familiarity with the facts as proved by the government will be assumed.
*172On (his reinstated appeal, Wyler makes three arguments: (1) there was insufficient evidence that Wyler was a knowing and purposeful member of the scheme to traffic in cocaine and heroin; (2) the trial judge improperly exercised his discretion in denying him a severance of his case for trial; and (3) he was “denied his Sixth Amendment right to compulsory process of witnesses favorable to the defense.” Each of these contentions will be dealt with hereinafter.
I
According to Wyler, the government offered no evidence to show that he knew of or participated in the charged conspiracy, which, as proved by the government, can be simply described as a heroin and cocaine business dominated by defendant Torrado. As Wyler views it, the only proof against him dealt with a June 8, 1968 transaction wherein one Estrada, an employee of Torrado, offered to sell some cocaine to Wyler. Wyler concedes that he, “acting as a go-between, obtained some money from another person in the bar and gave it to Estrada.” This narrow view overlooks other evidence of importance. There was testimony of a meeting, for example, on June 26, 1968 at the Butterscotchman Lounge. According to the testimony of one Gomez, he was then present during a conversation between Wyler and Boulier having to do with heroin. That conversation, according to Gomez, included a statement by Wyler (referred to as “Bobby the Italian”) that he would not be paying any more money for the heroin which he had been buying from Torrado. Furthermore, Gomez testified to a later conversation, apparently in July, 1968, wherein Torrado instructed Boulier to deliver i/^th kilogram to Bobby Wyler. Accordingly, we have no difficulty in concluding that there was sufficient non-hearsay evidence to permit the trial court to submit the case to the jury, United States v. Geaney, 417 F.2d 1116, at 1120 (2d Cir. 1969), and ample evidence, hearsay and non-hearsay, to convince a jury of Wy-ler’s guilt beyond a reasonable doubt. Id. at 1121. Moreover, contrary to the view of our dissenting colleague, we deem,this evidence sufficient to support the jury’s obvious finding that Wyler was no mere user of heroin and cocaine.
It is necessary to deal with a corollary argument advanced by Wyler to the effect that the evidence submitted about him to the grand jury was insufficient to sustain the indictment. As he correctly points out, the only evidence before the grand jury relating to Wyler was the testimony of Oscar Estrada. Before the grand jury, Estrada testified that on June 8, 1968, at the Butterscotchman Lounge he sold Wyler i/gth of a kilogram of heroin. As noted, his testimony at trial on this transaction was different in that he said that what he sold to Wyler on that day was i/sth kilogram of cocaine. Not surprisingly, this and another discrepancy were thoroughly explored by Wyler, who, with occasional assistance of attorneys Rosner and Mahler, ably defended himself at trial, on cross-examination of Estrada. It is perhaps sufficient for us to observe that this contention of Wyler is disposed of by the' rule of Costello v. United States, 350 U.S. 359 at 363, 76 S.Ct. 406 at 408, 100 L.Ed. 397 (1956), wherein it was held that federal indictments are not “open to challenge on the ground that there was inadequate or incompetent evidence before the grand jury.” But, assuming that the indictment is open to challenge for inadequate evidence, Estrada’s testimony, even with his error as to the type of hard drug involved, was certainly sufficient to indicate a reasonable probability of Wyler’s knowing involvement in the conspiracy charged. See Silverthorne v. United Stated, 400 F.2d 627, at 634 (9th Cir. 1968), appeal on remand 430 F.2d 675 (1970), cert, denied, 400 U.S. 1022, 91 S.Ct. 585, 27 L.Ed.2d 633 (1971) ; United States v. Potash, 332 F.Supp. 730 at 734 (S.D.N.Y.1971).
*173II
Prior to his trial, Wyler timely moved for an order severing his case for trial. He renewed this motion orally on the first day of trial. On those motions, as now, Wyler argued in substance that, absent severance, he would be unable to certainly obtain the testimony of certain co-defendants who, he claimed, would have demonstrated his lack of complicity in the conspiracy. Technically, we believe that the severance issue has already been resolved against Wyler by the panel of this court in United States v. Vega, supra, 458 F.2d at p. 1236. In any event, focusing upon this issue once again in respect to the peculiar facts pertaining to Wyler, it is only necessary to note that he was able to ask questions about his own involvement during the course of his cross-examination of certain co-defendants who took the stand at trial. For reasons which are obscure to us, it appears to be the view of our dissenting colleague that severance was required in order to permit Wyler to question all of his co-defendants. Even assuming that the remaining defendants would have been willing to testify, we doubt that their answers would have been more impressive than those given by other co-defendants at trial. Without extended discussion, therefore, we conclude that the trial judge was well within his discretion in denying the motions for severance; further, it is clear in hindsight that no prejudice resulted to Wyler by virtue of the judge’s rulings. It is, of course, horn-book law that co-conspirators’need not be shown to know one another; in this case, this principle has considerable practical importance due to the fact that four of the remaining defendants tried with Wyler were not “wholesalers” or their immediate agents but rather were “retailers” like Wyler.
III
Appellant also contends that he was unconstitutionally denied the right by the trial judge to issue subpoenas for witnesses and records favorable to his defense. See Washington v. Texas, 388 U.S. 14, 87 S.Ct.1920, 18 L.Ed.2d 1019 (1967). This contention effectively breaks into two separate parts, the first of which is plainly frivolous.
In his main brief on appeal, Wyler contended that the trial court erred in refusing to subpoena certain Central Intelligence Agency records and personnel as live witnesses. According „to that theory, Wyler obtained money from a third party in order to pay it over to Estrada on June 8th for the cocaine; the third party allegedly was an agent of the CIA operating under the cover name of “Alex Two”. In effect, then, the claim of appellant at trial and now is that he had been working for the CIA when he bought the cocaine on June 8th. Passing the inherent incredibility of such a claim, it is plain that the trial judge endeavored to come to a sensible solution of the problem; rather than allow a wholesale production of CIA records and unidentified personnel of that agency, he had the personnel director of the CIA, a Mr. Fred E. Lott, appear and testify for the appellant. (See SM2457-58). Not surprisingly, Mr. Lott’s testimony established that the CIA had no record of ever having employed Wyler or any of the other individuals he claimed were CIA employees dealing with him. We have no difficulty, then, in concluding that the trial judge properly exercised his discretion in regard to this aspect of the matter.
Apparently surmising that this court would reach such a conclusion, appellant and his counsel raised quite a different contention under this general heading in his reply brief on appeal. Specifically, Wyler therein claimed for the first time that the trial court erred in refusing to subpoena two witnesses, Lucretia Lum from Florida and one Clem Nash from Detroit. According to Wyler, Lucretia Lum could have testified that he, Wyler, was not known as “Bobby the Italian”, despite this identification by prosecution witnesses. Nash, a named defendant in the alleged conspiracy (though not on trial with *174Wyler), would have testified about some unspecified subjects which would cast in doubt the credibility of witnesses Estrada and Gomez. We have little difficulty with the Nash request, if only because the record is totally unclear that he could have given any helpful testimony to appellant. Thus, the trial judge was well within his discretion to refuse, as he did, to call Nash because Wyler and assisting counsel Rosner were not only distressingly vague as to Nash’s potential “evidence” but also aware that Nash might invoke his Fifth Amendment privilege. (SM2458-60)
Because the government had offered evidence tending to establish that Wyler was known as “Bobby the Italian” by other conspirators, the question regarding Lucretia Lum is arguably a closer one. Assuming, as Wyler does, that Miss Lum would not have invoked her privilege under the Fifth Amendment, we still note that there was no particular assurance that she, allegedly a girlfriend of principal defendant Torrado, would have been in any position to testify that Wyler was not called “Bobby the Italian”. As Wyler himself put it, “I would like to see if she knows who Bobby the Italian is”. (SM2461). The trial judge, who struggled constantly through the long trial to pass on Wyler’s legion requests for witnesses, was painfully aware of his responsibilities in this area. (See, e. g. SM2008-9; 2348-46; 2458-61.) As applicable Rule 17(b), F. R.Cr.P., indicates by its terms, the trial court is obliged to be satisfied that the production of a desired witness is “. . . necessary to an adequate defense.” Unlike the dissent, we cannot find that the aforementioned quotation of Wyler was an “explicit, relevant and important” offer of proof. Wyler at this point said nothing further; hence we are left with the unmistakable inference that Wyler himself had no reason to know what Miss Lum would say about this matter. Earlier, during another colloquy between the court, Wyler and other counsel, it is true that Wyler had stated that he wished to ask Miss Lum about the “credibility” of Estrada and Gomez. Government counsel immediately responded that he would object — with what we consider to be good reason — to any views which Miss Lum might have as to the credibility of Gomez and Estrada. Moreover, the trial judge thereupon turned to Mr. Rosner, who was then assisting Wyler, saying: “Now, do you want Miss Lum up here . ?” Rosner replied: “I don’t want her up.” (SM2345-46). With this state of the record, we cannot say that the trial court abused its discretion in concluding that there was no reasonable certainty that Miss Lum would testify in a manner helpful to Wyler. See United States v. Lepiscopo, 458 F.2d 977, at 978 (10th Cir. 1972); United States v. Panczko, 429 F.2d 683, at 688-689 (7th Cir. 1970).
The judgment of conviction is affirmed.