BROWN, Chief Judge:

The question is, must the Parole Board grant a Morrisey -type revocation hearing to a parolee at the commencement of a new prison sentence imposed for a crime committed while on parole where a parole violators warrant has been issued but returned unexecuted pending completion of the intervening sentence? Reversing the District Court, we hold that the revocation hearing can be postponed.

In 1966, while out on parole in Texas, under a federal bank burglary conviction, Appellee was returned to federal custody under two charges of post office burglary and one charge of burglary of a federally insured bank. On March 17, 1966 Appellee was released on $23,000 bond but was rearrested on March 28 on a charge of unlawfully attempting to enter yet another bank.

The following day the Parole Board issued a parole violators warrant charging Appellee with violating the conditions of his parole. The warrant was delivered to the United States Marshal for the Eastern District of Texas with instructions to (1) place a detainer if Appellee was apprehended by, and in custody of, local authorities and (2) to return the warrant unexecuted if the prisoner was sentenced on a new federal charge. The warrant was placed as a detainer against Appellee. Once again Appellee was prepared to make bond but decided not to when informed that the presence of the detainer would preclude his release in any event.

While in custody, Appellee was granted a preliminary interview with a United States probation officer pertaining to the issuance of the parole violators warrant. At this time, Appellee stated that he wished to fill out parole form 59(a) requesting a hearing before the Parole Board on return to a federal penal institution. The parole officer forwarded this request to the Parole Board.

On April 26, 1966 Appellee pleaded guilty to all four federal charges and received two five year sentences and one ten year sentence to run concurrently and one five year sentence to run consecutively. The five year consecutive sentence was suspended.

The parole violators warrant was not served on Appellee but was returned to the Parole Board unexecuted. This was not inadvertent but pursuant to earlier instructions to the Marshal and the apparently long established policy of the Parole Board. Appellee did not receive a revocation hearing on return to the federal prison nor thereafter although he repeatedly sought one.

The violators warrant was finally executed on March 30, 1972 on the eve of Appellee's completion of the service of his sentence at Leavenworth. In March, May and July Appellee was informed that he would be afforded a revocation hearing before the Parole Board. The hearing was held in July but Appellee voluntarily declined to appear. Following the hearing the Parole Board issued a written order revoking Appellee's parole, and ordering him to serve the 1,170 days remaining under his original sentence (see note 2, supra).

The District Court granted the request for mandamus ordering Appellee discharged from custody concluding that the parole violators warrant was "technically" executed in 1966, that it was a denial of due process as a matter of law to delay the revocation hearing for six years in view of Appellee's numerous requests for an earlier hearing, and that the attempted execution of the warrant in March 1972 constituted a denial of due process and abuse of discretion by the Parole Board. Federal statutes and the precedent of this Circuit compel us to reverse.

In Morrisey v. Brewer, supra, the Supreme Court established that in order to comply with due process, the parolee is entitled to certain procedural safeguards before parole may be revoked. The parolee must be afforded a preliminary probable cause hearing when he is arrested for a parole violation and a more thorough revocation hearing within a reasonable time after he is taken into custody.

Even prior to Morrisey an opportunity for a parole revocation hearing was provided by federal statute as well as by Justice Department regulations. Where a hearing is required procedure must, of course, measure up to the due process requirements mandated by Morrisey.

The instant case raises a question of timing — that is when must the federal parole revocation hearing be held where the parolee has been returned to prison under an intervening conviction and the parole violators warrant has been returned unexecuted.

While a parole violators warrant must be issued within the maximum term of the sentence in accordance with 18 U.S.C.A. § 4205 it need not be executed during this period. Instead, as we have many times declared, the warrant may be held in abeyance while the parolee serves sentence under an intervening conviction (the occurrence of which prompted the issuance of the violators warrant) and may then be executed following completion of this intervening sentence. Smith v. Blackwell, 5 Cir., 1966, 367 F.2d 539; Galloway v. Attorney General, 5 Cir., 1971, 451 F.2d 357; Cox v. Feldkamp, 5 Cir., 1971, 438 F.2d 1; Williams v. United States Board of Parole, 5 Cir., 1970, 428 F.2d 1210; Clark v. Blackwell, 5 Cir., 1967, 374 F.2d 953; Buchanan v. Blackwell, 5 Cir., 1967, 372 F.2d 451.

A parole violators warrant is executed when its command is carried out — that is when the parolee is retaken and returned to federal custody pursuant to it. But the return to federal custody must be by virtue of the parole violators warrant, not as was the case here, under the new intervening sentence for the recent crimes. See Johnson v. Wilkinson, 5 Cir., 1960, 279 F.2d 683.

Both statute and precedent confirm that execution of the warrant is the operative factor in triggering the availability of the revocation hearing. The hearing authorized by 18 U.S.C.A. § 4207 and 28 C.F.R. 2.40 is applicable to "a prisoner retaken upon a warrant." And in Galloway v. Attorney General, 5 Cir., 1971, 451 F.2d 357, we explicitly recognized that the right to a federal parole revocation hearing does not accrue while the parolee is serving an intervening federal sentence where the parole violators warrant remains unexecuted.

Appellee was not "retaken upon the warrant" in 1966 since he was already in federal custody under the four charges to which he eventually pleaded guilty. Thus the warrant was returned unexecuted, in accordance with the Parole Board's instructions. In an attempt to activate the § 4207 hearing requirement Appellee contends and the District Court held that the warrant was in fact "technically" executed since when filed as a detainer it effectively served the purpose of an executed warrant by preventing Appellee's release regardless of whether he made bond on the new charges. "Technically," however, we must conclude that the warrant was not executed in 1966 because Appellee was in fact held in custody pursuant to the four federal charges despite the subsequent lodging of the warrant as a detainer. The apparent futility of furnishing bond under these circumstances did not execute the warrant.

To hold otherwise would effectively vitiate Smith v. Blackwell, supra, and the cases which are binding on this panel that have expressly approved the Parole Board's common, if not standard, practice of deterring execution of the warrant until the intervening sentence has been served since the parolee will no doubt frequently be returned to custody pursuant to new federal charges prior to the issuance of the violators warrant.

We wish to emphasize that where the parole revocation hearing is deferred pending service of the intervening sentence, the parolee is not left without notice of the issuance of the violators warrant nor review of the propriety of its continued existence as a detainer.

Under 28 CFR 2.37(c) the Board in its discretion may provide a dispositional interview at the federal prison for a parolee who is serving an intervening sentence with an outstanding unexecuted violators warrant lodged as a detainer, at which time the continued propriety of the detainer may be challenged.

While in custody under the federal charges prior to pleading guilty, Appellee requested and received an interview with a local probation officer pertaining to the presence of the violators warrant then lodged as a detainer.

Nor was Appellee's case that of the forgotten person. The written report filed by the Parole Board subsequent to the 1972 revocation hearing affirmatively states that Appellee's case was reviewed by the Board several times during the course of his intervening sentence.

We realize that our decisions approving the deferral of the revocation hearing while the parolee serves an intervening sentence predated Morrisey. In concluding that the deferral of the hearing did not deprive Appellee of any rights prescribed by Morrisey, we emphasize that Appellee has not shown that he was prejudiced by the delay.

The District Court found that "the refusal of the Parole Board to grant a parole revocation hearing upon the request of Don Cook and his attorney, and the inability of Don Cook to be released from incarceration as a result of the parole violator warrant, materially altered his course of action in the defense of other charges outstanding against him at the time." This finding will not withstand the modest scrutiny required by the clearly erroneous rule since it is simply not supported by the record. There literally was no, not just insufficient, evidence to show what if any courses of action were open or foreclosed. Indeed, to this day there is no suggestion of what Appellee could or would have done nor anything which detracts from the validity and consequence of the plea of guilty to the new charges which constituted irrefutable proof of the parole violation.

As contemplated by Morrisey, the Parole Board must make two separate determinations at the revocation hearing: (1) Whether the parolee has in fact violated a condition of his parole and (2) what action should be taken by the Board if such a violation has occurred. 408 U.S. at 479-480, 92 S.Ct. at 2598, 33 L.Ed.2d at 493. In describing the nature of the revocation hearing in Morrisey, the Supreme Court expressly observed that "a parolee cannot relitigate issues determined against him in other forums, as in the situation presented when the revocation is based on conviction of another crime." 408 U.S. at 490, 92 S.Ct. at 2605, 33 L.Ed.2d at 499.

Appellee did not even begin to demonstrate that he could have presented a stronger showing of mitigating circumstances supporting non-revocation had the hearing been held earlier. This is especially true in light of the fact that a formal hearing was finally held at which Appellee deliberately did not appear and in which the Board revoked parole. If after the expiration of the intervening sentences the Board concluded that revocation was called for there is no showing here that either the facts and circumstances or the attitude of the Board would have led to a different result had hearings been held earlier.

Appellee also contends that he was prejudiced during the term of his intervening sentence in that the presence of an unexecuted parole violators warrant serving as a detainer results in the deprivation of certain prison privileges such as trustee status and various educational opportunities. We are unable to conclude on this record that the extent of such deprivation is so great or so unreasonably related to the very existence of a detainer — based as it is in this case on a serious and incontestable parole violation — as to require that the revocation hearing be held at the commencement of the intervening sentence. See Lawrence v. Blackwell, N.D.Ga., 1969, 298 F. Supp. 708.

Appellee also asserts that the deferral of the revocation hearing coupled with the presence of the detainer caused him great anxiety and interfered with the rehabilitation process since it is difficult for a parolee to become motivated while laboring under the uncertain prospect of further imprisonment following completion of his current sentence. We are simply unqualified, unauthorized, and unwilling to second guess the Parole Board on a matter so peculiarly within its own expertise.

We do not close our eyes to the fact that Appellee may have been disadvantaged in certain respects by the deferral of the revocation hearing but we are unable to conclude that the disadvantage constitutes such a grievous loss — in due process terminology — as to require the hearing be held prior to service of the intervening sentence or to permit the intrusion by a Court into this highly discretionary activity.

Underlying the District Court's decision was the proposition that the revocation hearing must be held within a reasonable time. Morrisey, in fact, recognized that " [t] he revocation hearing must be tendered within a reasonable time after the parolee is taken into custody." 408 U.S. at 488, 92 S.Ct. at 2603, 33 L.Ed.2d at 498. It is important to realize, however, that in Morrisey the Court was confronted with parolees who had been returned to prison under executed warrants — not under new intervening convictions for admitted, serious crimes.

The District Court concluded that "the attempted execution of the parole violator warrant in March of 1972, more than six years after the issuance thereof, is a denial of due process as a matter of law and an abuse of discretion by the parole officials. Simon v. Moseley, 10 Cir., 1971, 452 F.2d 306 and McCowan v. Nelson, 9 Cir., 1970, 436 F.2d 758." As noted above our precedents clearly refute that conclusion. Furthermore neither of the cases cited by the District Court supports its holding.

As we have pointed out, Appellee received a full federal parole revocation hearing — which he declined to attend — prior to the revocation of his parole. He does not show that this hearing lacked any of the various ingredients required by Morrisey. Nor does, nor can, he show that the result would have been different had this hearing been held earlier. The District Court's discharge of Appellee from federal custody was unwarranted.

Finally, Appellee claims that he is entitled to credit under 18 U.S.C.A. § 3568 for the 25 days spent in jail between March 28, 1966 when he was rearrested and April 21 when he pleaded guilty during which time he was unable to obtain release from custody due to failure to make bond coupled with the presence of the detainer. Whatever the significance of the 1966 amendments to § 3568 (June 22, 1966, Pub. Law 89-465, 80 Stat. 21, 18 U.S.C.A. § 3568) he is not entitled to credit against his original sentence but only, at most, credit against the sentences for the new intervening crimes. Claims of this kind are best determined administratively so we express no opinion as to this.

Reversed.