Hart and Robles appeal their convictions for distributing cocaine in violation of 21 U.S.C. § 841 (a)(1). The appellants, who were tried separately, sold cocaine to government agents pursuant to arrangements made by paid informants. Their only defense was entrapment.

The appeal presents two questions: (1) Did the district court err in denying the appellants’ respective motions to continue for failure of the government to produce the informant Murrieta, who was the key figure in the sale and upon whom the appellants depended to prove their entrapment defenses? (2) Did the district court err in foreclosing Robles from raising the entrapment defense because he refused to take the stand and there to admit the offense?

I.

The court took this case en banc to determine whether the government was a “guarantor” of the presence of an informant at the trial of a ease in which he had been used. We hold that it is not, and adhere to the rule that the government must use reasonable efforts to produce a government informant whose presence has been properly requested by the defendant. United States v. Leon, 487 F.2d 389 (9th Cir. 1973); United States v. Jenkins, 470 F.2d 1061 (9th Cir. 1972); Tapia-Corona v. United States, 369 F.2d 366 (9th Cir. 1966); Velarde-Villarreal v. United States, 354 F.2d 9 (9th Cir. 1965).

The record discloses the essential facts. The government availed itself of the services of two Mexican nationals in the development of the case against the appellants. Their names were Borjorquez and Murrieta. The arrest and the trial took place in Tucson and the court ordered that the government agent, Lugo, “make effort to locate informants and procure their presence at trial.” Borjorquez was produced for interview on July 25 prior to the scheduled August 13 trial of appellant Hart to be followed immediately by the August 14 trial of Robles. He was questioned in the courtroom with the court interpreter assisting, and with the judge announcing his availability if required. Borjorquez identified both himself and Murrieta as being residents of Magdalena, Sonora, Mexico. He further explained that Murrieta “has a little store, a general merchandise store” where he sells groceries and gave the street intersection where the store was located. He stated that Murrieta did not come for the interview “because he’s ill and apparently in pain.”

On August 12, a hearing was held on a motion to continue because Murrieta, who by then had developed as the only knowledgeable informer, had not appeared for interview or for trial. Special Agent Charles Lugo of the Drug Enforcement Administration was questioned under oath. He testified that his contact had principally been by telephone conversations initiated by Murrieta or Borjorquez. He stated that he had talked to them at least a dozen times between July 9 and August 12, telling them they would have to be present for the trial. He talked to them at least six times after Borjorquez had appeared for his interview on July 25. At no time did either indicate he would not be present. The last time he conversed with them was on Sunday, August 11, when they called from Santa Ana, Mexico. They assured him then, as they had before, that they would be in Tucson for pretrial interview on the following day, Monday, and for the trial on Tuesday.

At the conclusion of this evidentiary hearing on Monday the trial court denied the motion to continue with leave to renew it on Tuesday if Murrieta still had not appeared. On Tuesday, the day of trial, Murrieta had not arrived and a further hearing was held. Lugo told the court he had received a telephone call from Borjorquez after he returned to his office on Monday following the evidentiary hearing. Lugo related he had told Borjorquez in very strong terms to get Murrieta and come to Tucson at once. He also told them to call him from Nogales, at the border, and that he (Lugo) would pick them up and drive them to Tucson. He had received no further word.

*800 Lugo also amplified his testimony regarding employment of informants by explaining that when they are “first documented as informants” they are advised that the DEA requires that if they participate in a case in any way and are asked to testify they must be present to testify. “That’s one of the requirements for informants.” 1 He further stated that to his knowledge neither had been in the United States and available to subpoena, since the Borjorquez interview on July 25. On one occasion he had sent $20 to them to come up but they had not done so. The court denied the motion for a continuance and the motion to dismiss as to each defendant. 2

It was suggested at oral argument that Murrieta could have been “detained” as a material witness when he appeared and testified for the government as an informant in a case in mid-May of the same year that was tried in the United States District Court in Tucson. This is probably correct. See United States v. Verduzco-Macias, 463 F.2d 105 (9th Cir. 1972); Bacon v. United States, 449 F.2d 933 (9th Cir. 1971). At least some inducement such as retention of a portion of the reward until the case was closed, could have been made. But this case is not akin to Bacon or Verduzco-Macias . There the putative witnesses were fugitives; they had not only shown a disinclination to cooperate but the Mexican aliens were subject to possible imprisonment should the government have wished to indict and prosecute. Every self-interest was on the side of their fleeing the jurisdiction. Here, Murrieta up to that mid-May (the date of his last physical presence in the United States) had always been cooperative. He had promised to testify in court in May in a narcotics case and had appeared and testified as he had promised. He had not at that time refused to cooperate in any respect so far as the record shows. Neither had he failed to keep any commitment to testify. Had he been taken into custody at that time when there was no apparent reason to distrust him, he might well have been a very unhappy witness to be kept away from his home, his family and his business from mid-May until mid-August. It was also argued that the government might have withheld a portion of his reward. Again, he had presumably been paid before and had still cooperated. Under the Department’s requirements to be available to testify he still risked the loss of future rewards if he failed to appear when requested. Was there any reason as a matter of foresight for Lugo to believe that this case was different?

The dissent acknowledges that the government must only use reasonable ef *801 forts to produce the informant. Part of the difference between the majority rationale and the dissent is the point at which “reasonable effort” is to be judged. We believe it to be as of the time the government is exerting its efforts to obtain the attendance of the witness, taking into consideration the background of performance and attitude of the desired witness as of that time. That would ordinarily be after the trial date had been established and as the case was progressing to the actual finalized trial date. At the time Murrieta was last in the United States as far as the evidence shows, (mid-May before the August 13 trial date) the trial date had not been established finally. Certainly as of that time there was no reason to suspect that future performance would be any less than the 100 percent performance of the past.

After Murrieta had returned to Mexico there was nothing to do but to accept his promises as given with the expectation that he would fulfill them, together with the inducements of expense money and travel assistance. As of now the record is, of course, silent as to whether Murrieta was on his way, met with accident, remained ill or otherwise unable to fulfill his promise or whether he was simply recalcitrant. Just as ex post facto verification of the correctness of a tip from an informer by discovery of the contraband does not justify a finding of probable cause based upon the tip alone, United States v. Moreno-Buelna, 524 F.2d 1129, 1133 (9th Cir. 1975), (Hufstedler, J., dissenting), so, too, in this case, the view from perfect hindsight disclosing that an informer did not in fact show up for a trial, does not thereby establish conclusively that there was no reasonable effort made to produce him, or by him to appear.

All of which brings us to the all important consideration of the function of the trial judge at this point and the effect of his determination. His finding was that the government had met its burden. “They’ve done everything reasonably necessary and proper that they could be required to do lawfully, to get these witnesses here.” The trial court had held two evidentiary hearings before making this determination. We hold that the trial court’s finding should be sustained unless clearly erroneous and that it was not clearly erroneous under these circumstances.

This court sitting en banc held in United States v. Page, 302 F.2d 81 (1962), that the clearly erroneous rule applied in criminal cases by analogy to Rule 52(a), Fed.R. Civ.P., when the trial court rules upon the admissibility of evidence in the face of a motion to suppress. The motion to suppress was based upon the contention that a consent to search had not been validly given. This court decided in Page that it was for the trial court to determine, given certain facts, whether consent had been given in form and whether that consent was “valid” else it was no legal consent. In Robles and Hart the court hears certain facts and must determine whether the government did everything “reasonably necessary” to obey its order to produce an informant. In Page we held that the question was one of fact and was governed by the “clearly erroneous” rule. Our view is that the same rule applies here. 3

In each case the responsibility of the trial court could be argued to involve a mixed question of fact and of law — in the case at bench, “reasonably necessary” versus the case in Page “no duress or coercion, express or implied” and “freely and intelligently given.” 4 This court in cases subsequent to Page had adhered to the rule that questions of fact (even where arguably mixed with law) in criminal matters are governed by *802 the clearly erroneous rule. 5 Other jurisdictions have applied the same test, some without considering the fact that Rule 52(a), Fed.R.Civ.P. only applies directly to civil cases. 6

Nor can it be convincingly established that the pretrial ruling was a “conclusion of law” and therefore not subject to the clearly erroneous rule. The cases cited in notes 5 and 6, supra, which applied the clearly erroneous rule, could all arguably be considered to involve a question of law as well as a finding of fact. In Lundgren v. Freeman, 307 F.2d 104 (9th Cir. 1962), we discussed the distinction between findings of fact to which the clearly erroneous rule applied and, borrowing from Commissioner v. Duberstein, 363 U.S. 278 , 80 S.Ct. 1190 , 4 L.Ed.2d 1218 (1960), decided that “[a] finding of fact, to which the clearly erroneous rule applies, is a finding based on the ‘fact-finding tribunal’s experience with the mainsprings of human conduct’.” Lundgren v. Freeman, supra at 115. In Velarde-Villarreal v. United States, 354 F.2d 9, 13 (9th Cir. 1965), the very issue was decided by this court: “We think whether there was a failure to expend every reasonable effort to obtain the witness is a question of fact for the trial judge.” Here, the trial court had before him the agent who was responsible for Murrieta’s presence at the pretrial and trial proceedings. As a “border court” the judge was familiar with the problems of obtaining Mexican aliens to testify and the means which could be said to be reasonable or lack reasonableness to obtain their testimony. He held two evidentiary hearings to assure himself that reasonable efforts had been made. It was for him to measure the quality of the effort and the sincerity of the officer’s words and actions. 7

Other circuits faced with the same problem have not gone beyond the “reasonable effort” standard. 8 None has been found *803 which has required that the government “guarantee” or “insure” the presence of the witness and we decline to do so here. That this informer lives south of the border does not alter our conclusion. An informer can go underground in New York City, Chicago or Los Angeles and be just as unavailable for pretrial or trial, and the same rules should and do apply. The informants here went back to Mexico because it was where they lived and where Murrieta had his store and Borjorquez earned his small livelihood. 9

In sum, we are unable to say that the finding of the trial court that the government used reasonable efforts to produce these informants was clearly erroneous. It must be remembered that it was the trial court which heard testimony on direct and cross-examination at two evidentiary hearings; that it was the trial court which observed the demeanor of the witnesses; and most importantly that it was the trial court which considered the options available to the agent at the time he made his decision and measured the reasonableness of the agent’s actions against the facts and options available to him at that time. 10 It is not our role as an appellate court to try this case de novo.

The decision of the trial court that the government did exert reasonable efforts to produce the informers, is affirmed, and appellants’ motion to continue was thus properly denied.

II. 11

In requiring Robles to admit the offense as a condition to his asserting entrapment, the district court relied on the Eastman line of cases that we overruled in United States v. Demma, 523 F.2d 981 (9th Cir., en banc, 1975). Demma applies to Robles whose appeal was pending when Demma came down. None of the doctrines that have been developed to limit the retrospective effect of new rules of law upon pending cases has any application to Dem-ma. That decision announced no new rule of law; it did not represent any “sharp break in the web of the law” (Milton v. Wainwright, 407 U.S. 371 , 381 n. 2, 92 S.Ct. 2174, 2180 , 33 L.Ed.2d 1 (1972) (Stewart, J., dissenting)). Indeed, Demma mended a break in the law caused by the aberrational Eastman cases and its spawn and reconciled the law of our Circuit with Sorrells v. United States, 287 U.S. 435 , 53 S.Ct. 210 , 77 L.Ed. 413 (1932); Sherman v. United States, 356 U.S. 369 , 78 S.Ct. 819 , 2 L.Ed.2d 848 (1958); and United States v. Russell, 411 U.S. 423 , 93 S.Ct. 1637 , 36 L.Ed.2d 366 (1973). The special retroactivity doctrines affecting the exclusionary rule stated in United States v. Peltier, 422 U.S. 531 , 95 S.Ct. 2313 , 45 L.Ed.2d 374 (1975), are irrelevant. Equally remote from the Demma context are those cases that have given limited retrospective application to new prophylactic procedural rules, for example, Halliday v. United States, 394 U.S. 831 , 89 S.Ct. 1498 , 23 L.Ed.2d 16 (1969), holding that McCarthy v. United States, 394 U.S. 459 , 89 S.Ct. 1166 , 22 L.Ed.2d 418 (1969), was not retroactive to guilty pleas taken before McCarthy was decided. The Eastman error is grounds for reversing Robles’ conviction.

Upon remand, the defendants and the government will have the opportunity to present the issues in the light of the factual and legal developments that have occurred since these cases were tried.

As to defendant Hart, the judgment of the court below is affirmed. As to defend *804 ant Robles, the judgment is reversed and remanded for proceedings not inconsistent with this opinion.

. “THE WITNESS: When they were first documented as informants, they were advised that the procedure of the Drug Enforcement Administration, one of them is that if they participate in any way or conduct any introductions and we ask them to come to court, or the defense requests them to come to court to testify on behalf of the Government, that they will be present to testify. That’s one of the requirements for informants.

“Q. BY MR. KNAUSS: Is that done as a matter of standard procedure in your agency?

“A. Yes, sir, it is, sir.

“Q. Did you do it yourself personally?

“A. Yes, sir.

“Q. Is this done with both Mr. Borjorquez and Mr. Murrieta?

“A. Yes, sir, I did.

“Q. Did you remind them of that procedure during any of your calls that you have told us about?

“A. Yes, sir. But it was indirectly referring to the other case that they had been up here before on. And I told them, that, well, I know they didn’t like the idea of testifying, but I told them that regardless of whether or not they liked it or not, anytime they did a case and they got paid by the Government for doing it, that they were part of the case and they were required to testify, they would have to testify.” R.T. Vol. 4 at 36-37.

. “It appears to me that the Government has met the burden that they must bear. They’ve done everything reasonably necessary and proper that they could be required to do lawfully, legally to get these witnesses here. The defendants have a little obligation themselves. They’ve known who these witnesses are, and have known basically where they are. They were — had an opportunity to interview one of them for three hours or better. I think we’ve bent over backwards for the defendants in this case and have given them far more latitude than I know of any case that says we must give a defendant under the circumstances.” R.T. Vol. 4 at 42.

. Said this court in Page at 83:

. In Page the trial court’s finding was reversed but because the trial court mistakenly assumed that as a matter of law because of a prior ruling, he was obliged to make the ruling that he did.

. E. g., United States v. Trice, 476 F.2d 89 (9th Cir. 1973) (finding corroboration of informant’s testimony sufficient not clearly erroneous): McKinney v. United States, 487 F.2d 948 (9th Cir. 1973) (finding that a defendant had not met burden of proof of incompetency to stand trial not clearly erroneous); Costello v. United States, 324 F.2d 260 (9th Cir. 1963) (clearly erroneous rule applied in considering whether evidence sustained finding that officers who arrested defendant acted upon probable cause).

. E. g., United States v. Jones, 475 F.2d 723 (5th Cir. 1973) (whether defendant’s statement as to where stolen money was hidden was voluntary judged by clearly erroneous test); United States v. Conner, 478 F.2d 1320 (7th Cir. 1973) (whether facts disclosed constituted reasonable grounds for arrest without warrant measured by clearly erroneous standard). See also 9 Wright & Miller, Federal Practice and Procedure, 2573, at 689 (1971 ed.); Lewis v. United States, 382 F.2d 232, 234 (8th Cir. 1967).

. The dissent states in support of an innuendo of a lack of due process that “Neither is it simple to decide whether the Government has participated, by ‘suggestion, procurement, or negligence’, in the unavailability of a witness, which is a denial of due process (United States v. Mendez-Rodriguez (9th Cir. 1971) 450 F.2d 1, 5 ; United States v. Tsutagawa (9th Cir. 1974) 500 F.2d 420 ), and a failure to use reasonable efforts to produce a government informant whose departure was aided by his reward money, which only potentially leads to a dismissal of an indictment.” (Emphasis added.) The insinuation that the government has “participated” in the absence of the witnesses is not supported by any evidence in the record and the trial court so found.

. United States v. Williams, 496 F.2d 378, 382 (1st Cir. 1974); United States v. Super, 492 F.2d 319, 321 (2d Cir. 1974); United States v. Jones, 492 F.2d 239, 242 (3rd Cir. 1974); United States v. Tatum, 496 F.2d 1282, 1284 (5th Cir. 1974); United States v. Pollard, 483 F.2d 929, 931 (8th Cir. 1973); United States v. Hayes, 477 F.2d 868, 871 (10th Cir. 1973); United States v. Cansler, 419 F.2d 952, 954 (7th Cir.), cert. denied, 397 U.S. 1029 , 90 S.Ct. 1278 , 25 L.Ed.2d 540 (1970).

This Circuit has followed Page a half dozen times and as recently as United States v. Townsend, 510 F.2d 1145, 1147 (9th Cir. 1975). Other Ninth Circuit cases are:

United States v. Chase, 503 F.2d 571 , 572 n. 3 (1974)

United States v. Agosto, 502 F.2d 612, 614 (1974)

United States v. Phelps, 490 F.2d 644, 646 (1974)

United States v. Rothman, 492 F.2d 1260, 1264 (1973)

United States v. Marshall, 488 F.2d 1169, 1186 (1973).

Page has been followed by the Sixth Circuit, United States v. Gargotto, 510 F.2d 409, 411 (1974); by the D.C. Circuit, Jackson v. United States, 122 U.S.App.D.C. 324 , 353 F.2d 862 , 865 n. 4 (1965); and by the Ninth Circuit, Martinez v. United States, 333 F.2d 405, 407 (1964).

. The dissent implies that the payment of the reward financed or “assured them adequate funds” to return to Mexico. There is no evidence to support such a suggestion. A hold out of payment due them would have created an inducement. There is no evidence that it would have accomplished its purpose.

. We note that the options available to the government to pay or not to pay the informants and to detain or not to detain Murrieta were all made prior to any record of broken promises. There was never any indication that the government participated, by suggestion or by procurement, in the unavailability of the witnesses.

. This portion of the opinion was prepared by Judge Hufstedler for an earlier draft and is used with her permission, having met the approval of a majority of the court.