SELYA, Circuit Judge.

Defendant-appellant Kelley Mala, a resident of the U.S. Virgin Islands, appeals his conviction on various drug-related charges. We affirm, without prejudice, however, to Mala's right to explore certain contentions in a more appropriate forum.

I. Background

On January 4, 1989, a federal grand jury in Puerto Rico indicted Mala. The grand jury twice revised the bill, a process that culminated in a five-count superseding indictment against a total of fourteen defendants. Three counts targeted appellant, charging him with conspiracy to import cocaine into the United States, 21 U.S.C. § 963 (1988), conspiracy to possess cocaine with intent to distribute it, 21 U.S.C. § 846 (1988), and using a telephone to facilitate importation of cocaine, 21 U.S.C. § 843(b) (1988).

Most of the named defendants were promptly arrested and tried. Some were convicted, some were not. Withal, the government exhibited seeming indifference toward appellant. It was not until February 22, 1991 — some 25 months after the original indictment surfaced — that government agents arrested him in St. Thomas, took him to Puerto Rico, and arraigned him on March 8, 1991.

From that point forward, matters progressed at a more celeritous clip. On April 22, 1991, Mala filed a motion to dismiss the indictment on speedy trial grounds, or in the alternative, to suppress certain evidence. The district court denied the motion on May 17. Four days later, Mala filed a notice of appeal contesting the denial of his prayer for suppression. Undeterred by the appeal, the district court ordered the trial to commence on May 23, 1991, as previously scheduled. On May 30, a jury found appellant guilty on all three counts.

Two potentially significant events occurred between the date of the verdict and the imposition of sentence. Some six weeks after the trial ended, this court dismissed the interlocutory appeal for want of jurisdiction after determining that the order refusing to suppress evidence was not immediately appealable. In roughly the same time frame, appellant filed a pro se motion alleging, among other things, that he had been victimized by ineffective counsel. The district judge denied this initiative on procedural grounds, ruling that such a motion could not be brought in advance of sentencing.

On November 8, 1991, the court sentenced appellant to a lengthy prison term and imposed other penalties. This appeal followed. In it, appellant is represented by successor counsel.

II. Analysis A. The Trial Court's Jurisdiction

Appellant seeks to persuade us that his conviction is a nullity because the district court lacked authority over the case at time of trial. The linchpin of this asseveration is appellant's insistence that a case cannot be pending in two courts at the same time; hence, the pendency of his appeal from the refusal to suppress had the double-barrelled effect of transferring the case to the appellate court and stripping the trial court of jurisdiction. We are not convinced.

Ordinarily, docketing a notice of appeal ousts a district court of jurisdiction over the underlying case. See, e.g., Coastal Corp. v. Texas Eastern Corp., 869 F.2d 817, 819 (5th Cir. 1989). There is, however, an important difference between interlocutory appeals not specifically authorized by statute and other, less problematic appeals. While an appeal from either a final order or an interlocutory order made immediately appealable by statute divests a district court of authority to proceed with respect to any matter touching upon, or involved in, the appeal, see 9 James W. Moore et al., Moore's Federal Practice ¶ 203.11, at 3-45 (2d ed. 1993), an interlocutory appeal that is brought without any colorable jurisdictional basis does not deprive the district court of jurisdiction over the underlying case. See United States v. Ferris, 751 F.2d 436, 440 (1st Cir. 1984); Hodgson v. Mahoney, 460 F.2d 326, 328 (1st Cir. 1972); see also 9 Moore's Federal Practice, supra, ¶ 203.11, at 3-52. Thus, when a litigant purposes to appeal a plainly unappealable order, the trial court may treat the appeal for what it is — a sham — and continue to exercise jurisdiction over the case. Were the rule otherwise, a litigant bent on vexation could temporarily divest a trial court of jurisdiction at whim.

This case aptly illustrates the point. Two days before his trial was scheduled to start, appellant "appealed" an interlocutory order that had been entered a few days earlier. He did not identify then, nor has he identified now, any jurisdictional hook on which his appeal arguably might hang. A transparently invalid appeal constitutes no appeal at all. Because Mala's appeal was of this sorry stripe, the district court retained the authority to try the case.

B. The Right to a Speedy Trial

Appellant contends that the charges against him should have been dismissed because of unpardonable delays in the proceedings. This contention must rise or fall on appellant's claim that too long a period of time intervened between his indictment and his arrest. This claim, in turn, implicates the Sixth Amendment, for the Speedy Trial Act, 18 U.S.C. §§ 3161- 3174 (1988), is not applicable to periods of delay antedating a defendant's arrest. See United States v. Zandi, 769 F.2d 229, 233 (4th Cir. 1985); United States v. Haiges, 688 F.2d 1273, 1274 (9th Cir. 1982).

The Sixth Amendment provides in pertinent part that "in all criminal prosecutions, the accused shall enjoy the right to a speedy . . . trial." U.S. Const., Amend. VI. This right attaches upon indictment or arrest, whichever first occurs. See United States v. MacDonald, 456 U.S. 1, 6-7, 102 S.Ct. 1497, 1500-02, 71 L.Ed.2d 696 (1981); Dillingham v. United States, 423 U.S. 64, 64-65, 96 S.Ct. 303, 303-04, 46 L.Ed.2d 205 (1975) (per curiam). The constitutional assurance serves many laudable purposes, chief of which is to limit the possibility that memories will fade, witnesses disappear, and needless delay impair an accused's ability to defend himself. See United States v. Ewell, 383 U.S. 116, 120, 86 S.Ct. 773, 776, 15 L.Ed.2d 627 (1966).

In Barker v. Wingo, 407 U.S. 514, 92 S.Ct. 2182, 33 L.Ed.2d 101 (1972), the Supreme Court established a four-part balancing test to be used in determining whether a defendant's constitutional right to a speedy trial has been abridged. These four factors are (1) the length of the delay; (2) the reasons for the delay; (3) the defendant's posture vis-a-vis the delay, especially in respect to assertions of the speedy trial right; and (4) the prejudice stemming from the delay. Id. at 530, 92 S.Ct. at 2192. These factors cannot be plugged into a formula that operates with scientific precision. Rather, they must be considered on a case-by-case basis "together with such other circumstances as may be relevant." Id.

Attempting to apply the Barker test in the circumstances at bar frustrates meaningful appellate review. The devoir of persuasion rests with the appellant to show error in the ruling below. Although he filed a motion to dismiss the indictment on speedy trial grounds, he did not accompany it with affidavits or other materials of evidentiary quality. What is more, he did not request an evidentiary hearing. In the end, the district court denied the motion without holding a hearing and without making specific findings. The briefs on appeal evince that the facts relevant to the second, third, and fourth furculae of the Barker test are hotly disputed. We have no reliable way of resolving these factual disputes in the rarified atmosphere of an appellate bench. It follows inexorably that appellant cannot carry his burden of demonstrating error in the ruling below: without better factual insights, we can neither shrug off the possible existence of a scenario completely supportive of the district court's ruling nor measure the relative probabilities as among competing scenarios. Consequently, Mala's assignment of error cannot prevail.

To illustrate our dilemma, it might well be, as the government suggests, that appellant eluded arrest; or, knowing about the indictment, failed to assert his speedy trial right for a protracted period of time; or, having had the good fortune to observe a dress rehearsal of the government's case, suffered no cognizable prejudice through the delay. If an evidentiary hearing shows any such scenario to be true — and we do not suggest that this will (or will not) prove to be the case — the facts might well defeat appellant's speedy trial claim, notwithstanding the extremely long period of pre-arraignment delay. See, e.g., Doggett v. United States, ___ U.S. ___, ___, 112 S.Ct. 2686, 2691, 120 L.Ed.2d 520 (1992); United States v. Brock, 782 F.2d 1442, 1447 (7th Cir. 1986). On this inscrutable record, we simply cannot tell.

Nor is it unbefitting to decide the point based on a burden-of-proof rule where, as here, appellant can fairly be held accountable for the opacity of the record. Under federal motion practice, no automatic entitlement to an evidentiary hearing exists. See Aoude v. Mobil Oil Corp., 892 F.2d 1115, 1120 (1st Cir. 1989) (explaining that pretrial motions "do not usually culminate in evidentiary hearings"). Thus, a litigant who believes that evidence should be taken in order to put a motion into proper perspective must, at the very least, call the need for a hearing to the court's attention and ask that a hearing be convened. A party who fails to meet this precondition cannot then complain that the court did not hold a hearing that it was never asked to hold. See United States v. Tardiff, 969 F.2d 1283, 1286 (1st Cir. 1992); Teamsters, Etc., Local No. 59 v. Superline Transp. Co., 953 F.2d 17, 20 n. 4 (1st Cir. 1992). District judges are not expected to be mind readers.

To sum up, "[d]ue process does not entitle the defendant to an evidentiary hearing where the defendant has failed to request one." Tardiff, 969 F.2d at 1286; accord United States v. Rigby, 896 F.2d 392, 395 (9th Cir. 1990). Because an evidentiary hearing was neither sought nor convened in this instance, the assignment of error premised on the defendant's constitutional right to a speedy trial succumbs for want of satisfactory proof.

C. Ineffective Assistance

The Sixth Amendment also provides that persons accused of crimes shall receive the benefit of counsel for their defense. See U.S. Const., Amend. VI. Appellant maintains that he was denied this safeguard because his trial counsel performed below any acceptable standard of proficiency. While this suggestion is not implausible on its face, we do not think it is ripe for our consideration. We explain briefly.

We have held with a regularity bordering on the monotonous that fact-specific claims of ineffective assistance cannot make their debut on direct review of criminal convictions, but, rather, must originally be presented to, and acted upon by, the trial court. See, e.g., United States v. McGill, 952 F.2d 16, 19 (1st Cir. 1992); United States v. Natanel, 938 F.2d 302, 309 (1st Cir. 1991), cert. denied, ___ U.S. ___, 112 S.Ct. 986, 117 L.Ed.2d 148 (1992); United States v. Hunnewell, 891 F.2d 955, 956 (1st Cir. 1989); United States v. Costa, 890 F.2d 480, 482-83 (1st Cir. 1989); United States v. Hoyos-Medina, 878 F.2d 21, 22 (1st Cir. 1989); United States v. Carter, 815 F.2d 827, 829 (1st Cir. 1987); United States v. Kobrosky, 711 F.2d 449, 457 (1st Cir. 1983). The rule has a prudential aspect. Since claims of ineffective assistance involve a binary analysis — the defendant must show, first, that counsel's performance was constitutionally deficient and, second, that the deficient performance prejudiced the defense, see Strickland v. Washington, 466 U.S. 668, 687, 104 S.Ct. 2052, 2064, 80 L.Ed.2d 674 (1984) — such claims typically require the resolution of factual issues that cannot efficaciously be addressed in the first instance by an appellate tribunal. See Costa, 890 F.2d at 483; Hoyos-Medina, 878 F.2d at 22. In addition, the trial judge, by reason of his familiarity with the case, is usually in the best position to assess both the quality of the legal representation afforded to the defendant in the district court and the impact of any shortfall in that representation. Under ideal circumstances, the court of appeals should have the benefit of this evaluation; elsewise, the court, in effect, may be playing blindman's buff.

To be sure, we have occasionally undertaken review of ineffective assistance claims on direct appeal, even without the advantage of the district court's views. See, e.g., Natanel, 938 F.2d at 309. But we travel this route only when the critical facts are not in dispute and the record is sufficiently developed to allow reasoned consideration of the claim. See id.

Although appellant invokes the exception on the theory that any lawyer worth his salt would have requested an evidentiary hearing, we think this case falls well within the compass of the usual rule. Even if we assume arguendo that trial counsel's performance was constitutionally deficient, appellant's thesis runs afoul of the second prong of the Strickland test. Under that prong, a criminal defendant must "show that there is a reasonable probability that, but for counsel's unprofessional errors, the result of the proceeding would have been different." Strickland, 466 U.S. at 694, 104 S.Ct. at 2068. On the sparse record presently compiled, we cannot say whether, had the speedy trial claim been litigated fully, it likely would (or would not) have led to a dismissal of the indictment. See supra Part II(B). Thus, because the record does not furnish proper illumination to enable us to assess probable outcomes, the issue of ineffective assistance is prematurely before us.

When faced with similar situations in comparable cases, we have routinely dismissed the relevant portion of the appeal without prejudice to the defendant's right to litigate his ineffective assistance claim through the medium of an application for post-conviction relief. See, e.g., McGill, 952 F.2d at 19 n. 5 (dismissing assignment of error without prejudice to the filing of a petition in the district court under 28 U.S.C. § 2255); Hunnewell, 891 F.2d at 956 n. 1 (same). We follow this sound practice today — but with an added wrinkle.

Three things coalesce here: (1) appellant has shown a fair likelihood of success on the constitutional claim, (2) that claim is factually complex and legally intricate, and (3) the facts are largely undeveloped and appellant (who is both incarcerated and indigent) is severely hampered in his ability to investigate them. This seems, therefore, to be the rare section 2255 case in which the appointment of counsel is warranted. See 18 U.S.C. § 3006A(a)(2)(B) (1993 Supp.) (stipulating that, if "the interests of justice so require, representation may be provided [under the Criminal Justice Act] for any financially eligible person who . . . is seeking relief under section . . . 2255 of title 28"); see also Battle v. Armontrout, 902 F.2d 701, 702 (8th Cir. 1990) (holding that the district court abused its discretion in failing to appoint counsel for habeas corpus petitioner); Richardson v. Miller, 721 F. Supp. 1087 (W.D.Mo. 1989) (finding, on particular facts, that the interests of justice dictated appointment of counsel in a § 2255 case). We thus direct the district court, if appellant petitions for section 2255 relief and demonstrates continued financial eligibility, to appoint counsel for him under 18 U.S.C. § 3006A(a)(2)(B).

III. Conclusion

We need go no further. We affirm the judgment below, without prejudice, however, to appellant's right to raise his claim of ineffective assistance in a proceeding brought pursuant to 28 U.S.C. § 2255. As stipulated herein, the district court shall, subject to the strictures of the Criminal Justice Act, appoint counsel for appellant should such a proceeding eventuate.

It is so ordered.