This is an appeal from a judgment of conviction entered on February 2, 1979, by the United States District Court for the Eastern District of New York, Henry Bramwell, Judge, after a jury trial, for three armed bank robberies, in violation of 18 U.S.C. §§ 2113(a), 2113(d), and 2. Appellant urges that the police lacked probable cause for detaining him prior to eliciting inculpatory statements and that certain statements introduced at trial were the inadmissible fruit of an unlawful arrest. For the reasons that follow, we reverse the judgment of the district court and remand the cause for proceedings consistent with this opinion.
The facts, briefly, are as follows. On April 17, 1978, two tall black males robbed the Chase Manhattan Bank, 3126 Avenue U, Brooklyn, New York. On April 25, two black males robbed the same bank; a bank employee testified at trial that she recognized the tall man who controlled the floor as the same in both robberies. A truck driver saw the robbers leave after the second robbery and was later able to describe the car in which they escaped, including its license plate. The following day, police on patrol spotted a car of a similar description, with a closely similar plate. (The witness had described the automobile as a blue Dodge Dart or a Nova with license plate number 552-CZZ or 352-CZZ; the automobile that appellant tried to enter was a rented blue Dodge Aspen with license plate number 552-ZCV.) According to testimony at the suppression hearing, the police saw appellant and another man unsuccessfully attempt to open the car’s doors, engaged the two men in conversation as to who owned the car, and asked them (and a third man who had joined them) to come down to the station to determine who owned the car. Appellant was detained for several hours in a holding pen until agents of the Federal Bureau of Investigation arrived. The agents told him that he was under arrest for the April 25 robbery, at which he blurted out “All right, you got me.” The agents immediately gave Miranda warnings to appellant and obtained a confession from him on the spot. They obtained a further confession the following morning, when they transported him to his arraignment.
Appellant was released on bail on April 27, 1978. On August 16, 1978, there was a robbery of a different bank in Brooklyn. Based on eyewitness testimony, the police arrested appellant for the robbery later that morning.
Appellant moved to suppress physical evidence and post-arrest statements concerning all three robberies. But with respect to the two April robberies, appellant explicitly limited the grounds for his motion to two issues, inadequate Miranda warnings and improper government influences to make the appellant talk, specifically disavowing any illegal arrest argument. During the December 11 hearing on the motion, how*1010ever, the judge permitted questioning on the issue of illegal arrest over the Government’s objection. Appellant raised the illegal arrest/poisonous fruit argument at the end of the hearing, and the court considered and summarily rejected it.
Under Fourth Amendment principles recently restated in Dunaway v. New York, 442 U.S. 200, 99 S.Ct. 2248, 60 L.Ed.2d 824 (1979), the Government has not on this record, satisfied its burden of proving by a preponderance of the evidence, see Brown v. Illinois, 422 U.S. 590, 604, 95 S.Ct. 2254, 45 L.Ed.2d 416 (1975), that the confessions on April 26 and April 27, 1978, were admissible and were not the fruit of an illegal arrest. First, the detention of appellant in the holding pen apparently did constitute an “arrest,” requiring a finding of the usual degree of probable cause, not the lesser degree permitted by the stop-and-frisk cases such as Terry v. Ohio, 392 U.S. 1, 88 S.Ct. 1868, 20 L.Ed.2d 889 (1968), and progeny. As in Dunaway, the police told the appellant to come down to the station for questioning, leaving him with the impression that until they were through with him, he was not free to leave. See Dunaway, supra, 442 U.S. at 208, 99 S.Ct. at 2254.
The dissent argues that Dunaway should not be applied retroactively because it decides a new question of law and broadens the exclusionary rule, and that the policy of deterrence said to underlie the exclusionary rule1 would not be served by applying it retroactively while the administration of justice would be unduly burdened by such application. But Dunaway does not purport to expand Fourth Amendment protections beyond the contours established in prior cases. Thus, although Dunaway was decided subsequently to the oral argument in this case, it establishes no “new principle of law,” Chevron Oil Co. v. Huson, 404 U.S. 97, 106, 92 S.Ct. 349, 30 L.Ed.2d 296 (1971), and we should apply it here. The general standard for nonretroactivity is discussed in Chevron Oil, supra, 404 U.S. at 106-07, 92 S.Ct. at 355:
First, the decision to be applied nonretroactively must establish a new principle of law, either by overruling clear past precedent on which litigants may have relied, see, e. g. Hanover Shoe, [Inc.] v. United Shoe Machinery Corp. [392 U.S. 481, 496, 88 S.Ct. 2224, at 2233, 20 L.Ed.2d 1231 (1968)], or by deciding an issue of first impression whose resolution was not clearly foreshadowed, e. g., Allen v. State Board of Elections [393 U.S. 544, 572, 89 S.Ct. 817, at 835, 22 L.Ed.2d 1 (1969)]. Second, it has been stressed that “we must * * * weigh the merits and demerits in each case by looking to the prior history of the rule in question, its purpose and effect, and whether retrospective operation will further or retard its operation.” Linkletter v. Walker [381 U.S. 618, 629, 85 S.Ct. 1731, at 1738, 14 L.Ed.2d 601 (1965)]. Finally, we have weighed the inequity imposed by retroactive application, for “[w]here a decision of this Court could produce substantial inequitable results if applied retroactively, there is ample basis in our cases for avoiding the ‘injustice or hardship’ by a holding of nonretroactivity.” Cipriano v. City of Houma [395 U.S. 701, 706, 89 S.Ct. 1897, 23 L.Ed.2d 647 (1969)].
The proper application of this three-fold standard in Fourth Amendment exclusionary rule cases is to be found in United States v. Peltier, 422 U.S. 531, 95 S.Ct. 2313, 45 L.Ed.2d 374 (1975), in which the Court declined to give retroactive application to Almeida-Sanchez v. United States, 413 U.S. 266, 93 S.Ct. 2535, 37 L.Ed.2d 596 (1973) (warrantless Border Patrol auto searches, without probable cause, unconstitutional). In Peltier the Court held that where law enforcement agents acted pursuant to a validly enacted federal authorizing statute whose predecessor dated back to 1946, “supported by longstanding administrative regulations and continuous judicial approval,” 422 U.S. at 541, 95 S.Ct. at 2319, a new *1011finding that such conduct violates the Fourth Amendment and requires application of the exclusionary rule should not be applied retroactively. The rationale was that in such cases the law enforcement officers did not know, and could not reasonably be charged with knowing, that their conduct was improper and that therefore neither the “judicial integrity” purpose, nor the deterrent purpose, of the Fourth Amendment exclusionary rule would be served by retroactive application. 422 U.S. at 537-38, 541-42, 95 S.Ct. 2313.
The issue here may be stated as whether a detention in a police station “holding pen” for several hours, for investigative purposes, may be brought within some sort of an expanded Terry v. Ohio, supra, stop-and-frisk exception to the probable-cause requirement. The principal issue in Brown v. Illinois, supra, concerned the per se efficacy of Miranda warnings in dispelling the taint of prior police illegality. The illegality, however, in Brown was an improper detention, about which the Court had this to say:
The impropriety of the arrest was obvious; awareness of that fact was virtually conceded by the two detectives when they repeatedly acknowledged, in their testimony, that the purpose of their action was “for investigation” or for “questioning.”
422 U.S. at 605, 95 S.Ct. at 2262. While the Court also mentions the fact that the manner of arrest appeared to aim at causing “surprise, fright, and confusion,” id., the principal emphasis of its analysis of the arrest appears to lie in its investigative purpose. Brown alone would be good precedent for the conclusion that the detention in the present case was illegal, unless probable cause can be established.
The dissent cites several cases which expressly condone “investigative detentions” under certain conditions, and implies by this argument either that these cases were overruled by Dunaway or that if they were not overruled by Dunaway it would have been reasonable to think, before Dunaway, that their principles properly applied to the present fact situation. Closer analysis reveals, however, that neither of these suggestions is correct and that, at most, Duna-way limits the holding of these cases to their own, and substantially similar, fact situations.
People v. Morales, 42 N.Y.2d 129, 397 N.Y.S.2d 587, 366 N.E.2d 248 (1977), cert. denied, 434 U.S. 1018, 98 S.Ct. 739, 54 L.Ed.2d 765 (1978), held that “[l]aw enforcement officials may detain a person upon reasonable suspicion for questioning for a reasonable and brief period of time under carefully controlled conditions which are ample to protect the individual’s Fifth and Sixth Amendment rights.” 42 N.Y.2d at 135, 397 N.Y.S.2d at 590, 366 N.E.2d at 251. However, in applying this standard the court specifically mentioned various exceptional circumstances that obtained:
A brutal and heinous felony had been committed. All of the indications raised by the “checkerboard square” of police investigation pointed at the defendant. Interrogation of the defendant was the only practical investigative technique open to the police. The period of detention was brief [fifteen minutes] and defendant, experienced in police procedures, was fully advised of his constitutional rights.
42 N.Y.2d at 132-33, 397 N.Y.S.2d at 588, 366 N.E.2d at 249. There has been no showing of any similar special circumstances in the present case (nor, of course, any showing to the contrary).2
*1012The dissent cites a number of Second Circuit cases as establishing that Morales reflects what “was for many years the law of this circuit,” dissent at 1017. All the cases here cited, however, precede Brown v. Illinois, supra. In fact, the most recent, United States v. Thomas, 250 F.Supp. 771, 790 (S.D.N.Y.1966), aff’d, 396 F.2d 310 (2d Cir. 1968) (statements made on street corner before entering police vehicle), precedes Brown by over half a decade.
More recent cases are mentioned. One, United States v. Oates, 560 F.2d 45 (2d Cir. 1977) (airport patdown), is clearly distinguishable from Dunaway, and from the present case, as it involved what the court there described as “a classic stop and frisk,” 560 F.2d at 58. Whatever else Dunaway does, it certainly does not disturb the Terry standard as applied to the “classic stop and frisk.” Another case, United States v. Rico, 594 F.2d 320 (2d Cir. 1979) (investigative stop at airport), is cited as supporting the legality, pre-Dunaway, of investigative detentions. Again, however, Rico is clearly distinguishable from Dunaway and from the present case. In Rico, the brief investigative stop which was justified under the Terry rationale, as explained in Adams v. Williams, 407 U.S. 143,146, 92 S.Ct. 1921, 32 L.Ed.2d 612 (1972), “rapidly developed evidence sufficient to justify appellant’s arrest.” 594 F.2d at 326.
In our view, then, there is no basis for the position that Dunaway “overrules clear past precedent” or “decides an issue of first impression whose resolution was not clearly foreshadowed.” True, the New York Court of Appeals had held that under limited circumstances investigative detention was legal without probable cause, and the Supreme Court in Dunaway reviewed and reversed the Appellate Division’s application of that standard to a fact situation similar to that in the present case. Surely, however, one prior incorrect holding by a lower state court does not make a Supreme Court decision a “sharp break” with the past. There are no other cases cited in the dissent which were clearly overruled by Dunaway. We are thus compelled to find that on the present record, the Government has failed to show that the police and FBI agents could reasonably have believed that their conduct was lawful. Under principles stated in Brown and reiterated in Dunaway, an involuntary prolonged detention in a police station is an “arrest” requiring the usual degree of probable cause.
On this record, there is a serious question whether the police had probable cause to arrest appellant when they brought him to the station. Although this is a closer question than the question whether appellant was arrested, the only evidence connecting him to the crime was apparently3 that (like one of the robbers) he was a tall black male, that he was trying to enter an automobile, and that there was substantial reason to believe that the automobile had been used in the bank robbery the day before.
If the detention of appellant was illegal because not supported by probable cause, the Government has not shown that the taint had dissipated when the FBI secured confessions from appellant the afternoon of his arrest and the following day. To decide whether the statements were obtained by exploitation of the illegality of the arrest, we must examine “[t]he temporal proximity of the arrest and the confession, the presence of intervening circumstances, . and, particularly, the purpose and flagrancy of the official misconduct . . . .” Brown v. Illinois, supra, 422 U.S. at 603-04, 95 S.Ct. at 2261-62 (footnote omitted). Here, as in Dunaway, although the official misconduct was not egregious, the arrest and confession were very close in time, and *1013the defendant was in continuous police custody. The issue thus turns on whether “any intervening event of significance,” Dunaway, supra, — U.S. at 218, 99 S.Ct. at 2259, occurred. The Government suggests that the arrival of the FBI agents several hours after state police brought appellant to the “holding pen” was such an event because the FBI then had probable cause to arrest appellant. But this suggestion is not altogether convincing. As an abstract matter, such intervening probable cause would probably dissipate the taint, see United States v. Morris, 597 F.2d 341 (2d Cir. 1979) (per curiam). But there is some doubt here that the FBI agents had probable cause to arrest appellant when they did so, for they subsequently showed appellant several bank surveillance photographs and asked him to identify himself, stating that they had been “confused as to which one was Mr. Tucker.” The only evidence on this record that the FBI had probable cause to arrest him before they told him he was under arrest (and before he blurted out “All right, you’ve got me” and identified himself from the photographs) is Agent Kaminski’s testimony: “When I arrived [at the station], I had on my possession bank surveillance photographs . . . Based on that photograph, I called the Eastern District of New York and got authorization to arrest Charlie Tucker.” This statement is too vague to demonstrate probable cause.
The Government suggests that even if the April statements are suppressible, appellant adopted the admissions six months later on October 31, 1978, in the presence of his first lawyer and the prosecutor. But we do not believe that the failure to suppress the earlier statements was therefore harmless error. The defense had a colorable objection to the introduction at trial of those later statements, and pursuant to a stipulation the Government did not introduce these statements at trial. The earlier confessions were introduced at trial, and the Government heavily relied upon them in its prosecution for the two April robberies. Of course, appellant was also convicted of a third robbery, a conviction which was untainted by the other convictions, as the Government notes. Although appellant received a general twenty-year sentence on each of the three robberies, to run concurrently, the Government does not invoke the concurrent sentence doctrine, see Weems v. Follette, 414 F.2d 417 (2d Cir. 1969), cert. denied, 397 U.S. 950, 90 S.Ct. 973, 25 L.Ed.2d 131 (1970). Since there may be some prejudicial collateral consequences, see United States v. Hines, 256 F.2d 561, 563 (2d Cir. 1958), we decline to rely upon the doctrine.
Notwithstanding the Government’s inadequate proof, we remand the case because it was not the Government’s fault that the record is so “barren” (as the Government admits). We therefore remand for reconsideration, after further findings, of the following matters:
1. Whether the detention of appellant on April 26,1978, prior to his questioning by FBI agents, constituted an “arrest” requiring the ordinary high degree of probable cause;
2. Whether the State had the requisite degree of probable cause to detain appellant;
3. If not, whether the statements obtained from appellant after his detention were obtained in exploitation of the illegal detention, giving particular attention to whether, when the FBI formally arrested appellant, they had probable cause to do so.
Cause remanded for further proceedings consistent with this opinion.
. But see Schrock & Welsh, Up from Calandra: The Exclusionary Rule as a Constitutional Requirement, 59 Minn.L.Rev. 251 (1974).
. It should be noted in passing that when Dun-away was decided by the Appellate Division in New York, 61 A.D.2d 299, 402 N.Y.S.2d 490 (1978) (the decision subsequently overturned by the Supreme Court), the dissent strongly contended that the majority was improperly broadening the rule of Morales:
The majority read Morales to posit a broad test of reasonable police conduct under all the circumstances. Instead Morales sets forth a tightly drawn and carefully articulated rule limited to exceptional circumstances. In reversing the trial court’s suppression order, the majority extend the ambit of Morales *1012beyond these established parameters and in so doing violate Dunaway’s rights in light of Brown v. Illinois, supra.
Id. at 307, 402 N.Y.S.2d at 495 (dissenting opinion). This is not to say that Morales, supra, was good law after Brown v. Illinois was decided or, a fortiori, after Dunaway. On that question we express no opinion.
. We have only the FBI agent’s hearsay testimony on this point. The Government did not call the arresting local police officers because the motion to suppress was not on this ground.