HARRIS, Associate Judge:
Appellant challenges his conviction of armed robbery (D.C.Code 1973, §§ 22-2901 and -3202) on the grounds that his in-court identification was the “fruit” of an illegal arrest, which hence should have been excluded as evidence. We affirm.
I
On the morning of January 3, 1974, a woman was robbed at gunpoint in the ladies’ restroom on the grounds of the Washington Monument, Her assailant, peering through the crack between the door and the side of the stall that she occupied, requested admission and demanded $10. She refused, whereupon he pointed a [1065]*1065pistol at her and repeated his demands. She gave him $10, but he insisted that she open the stall door. When she did so, the gunman made sexual advances, including touching her breasts and asking her to perform fellatio. She resisted and pleaded with him to leave, which he finally did.
A similar incident occurred on the afternoon of January 6. In the same restroom, two other women were forced to surrender $20 to a youth who was wielding a broken bottle. All three victims described their assailant to the police as a 15-to-18-year-old Negro male of slender build and light complexion.
Three days later, Officers Rayfield and Barg of the United States Park Police observed appellant in the vicinity of the Monument. They stopped him and asked his name and age. He gave his name and his age, which was 16.1 The officers asked why he was not in school, and said that he bore a likeness to the descriptions given by the robbery victims. Appellant replied that he had just “walked away from school”, and the officers allowed him to go on his way. They then asked James Dickens, a tour guide who believed that he had seen the assailant of the first victim on January 3, if appellant looked familiar. Dickens responded that he thought appellant had been in the area that day. The Park Police officers stopped appellant a second time and summoned Detective Ore, the Metropolitan Police officer in charge of the robbery investigation. The detective' arrived a few minutes later and attempted to take a picture of appellant to show to the robbery victims. When it was realized that inclement weather precluded acceptable photography, Detective Ore took appellant into custody as a suspected truant and transported him to Park Police Headquarters. He was detained there for approximately one hour, during which time the detective telephoned appellant’s school, and the youth was photographed and interviewed.2 Appellant then was released.
On the following day, the first victim was shown an array of eight photographs, including that of appellant. Although previously she had selected no suspect after viewing several hundred mugshots, she immediately identified appellant as her assailant. One of the other two victims made a similar identification of appellant from the photographs. Later, the first victim again identified appellant at a lineup.
Appellant filed a pretrial motion to suppress all identification testimony, contending that his detention for truancy had been' a pretext to seek evidence for the robbery investigation, and that being the product of his illegal detention, the identification testimony was inadmissible. Following extensive testimony by appellant, the three victims, and Officer Rayfield and Detective Ore, the trial court found that the second detention constituted an arrest, and that as such it was defective for lack of probable cause. The court ruled that the photographic and lineup identifications would be excluded. However, on the grounds that the victims’ ability to identify the robber (based on their face-to-face encounters with their assailant) was unaffected by the police conduct, it concluded that in-court identifications should be permitted. The jury convicted appellant of the armed robbery of the first victim, but [1066]*1066found him not guilty of all other charges.3 Appellant now contends that the trial court erred in permitting the in-court identifications.
II
Appellant’s challenge to the identification testimony by the three women rests upon the “fruit of the poisonous tree” doctrine developed in Silverthorne Lumber Co. v. United States, 251 U.S. 385, 40 S.Ct. 182, 64 L.Ed. 319 (1920), Wong Sun v. United States, 371 U.S. 471, 83 S.Ct. 407, 9 L.Ed.2d 441 (1963), and their progeny. He contends that the in-court identifications were the result or “fruit” of an illegal arrest and detention, and therefore were inadmissible. We reject both his premise and his conclusion.
In Wong Sun, the Supreme Court held that in certain circumstances, evidence which the government has acquired either directly or indirectly as a result of a violation of an accused’s Fourth Amendment rights may not be used to secure his conviction. See Mapp v. Ohio, 367 U.S. 643, 81 S.Ct. 1684, 6 L.Ed.2d 1081 (1961); Silverthorne Lumber Co. v. United States, supra; Weeks v. United States, 232 U.S. 383, 34 S.Ct. 341, 58 L.Ed. 652 (1914). While the principle applies to testimonial as well as to tangible evidence [Wong Sun v. United States, supra, 371 U.S. at 485-86, 83 S.Ct. 407; see also Bond v. United States, D.C.App., 310 A.2d 221, 224-25 (1973)], the Wong Sun Court emphasized that the reach of the exclusionary rule is not unlimited (371 U.S. at 487-88, 83 S.Ct. at 417):
We need not hold that all evidence is “fruit of the poisonous tree” simply because it would not have come to light but for the illegal actions of the police. Rather, the more apt question in such a case is “whether, granting the establishment of the primary illegality, the evidence to which instant objection is made has been come at by exploitation of that illegality or instead by means sufficiently distinguishable to be purged of the primary taint.” Maguire, Evidence of Guilt, 221 (1959).
Cf. United States v. Wade, 388 U.S. 218, 240-41, 87 S.Ct. 1926, 18 L.Ed.2d 1149 (1967); see also Nardone v. United States, 308 U.S. 338, 340-41, 60 S.Ct. 266, 84 L.Ed. 307 (1939). Accepting the trial court’s finding that appellant’s detention constituted an arrest for which the police lacked probable cause, the question for our determination is whether the in-court identification testimony by the robbery victims properly may be characterized as evidence which resulted from an impermissible “exploitation” of that arrest. We conclude that it may not.
The challenged identifications rested upon the concurrence of (1) the ability of the witnesses to render such evidence (i. e., the knowledge upon which their testimony was based), and (2) the opportunity for the presentation of the incriminating testimony (i. e., the presence of both the witnesses and the accused in the trial). A witness’ testimony may be held inadmissible when it rests upon knowledge or recollections of the underlying transaction which have been provided or significantly supplemented by improper police activity. Cf. United States v. Wade, supra, 388 U.S. at 239-40, 87 S.Ct. 1926; People v. Stoner, 65 Cal.2d 595, 55 Cal.Rptr. 897, 901, 422 P.2d 585, 589 (1967). Here, however, there was no such fatal infection. Cf. Pender v. United States, D.C.App., 310 A.2d 252 (1973). The trial court ruled that the identification testimony rested upon the independent basis of the victims’ face-to-face encounters with their assailant, and we find its conclusion amply [1067]*1067supported by the record.4 See D.C.Code 1973, § 17-305(a).
While appellant correctly observes that the poisonous tree doctrine is not confined to the direct “fruits” of police misconduct (e. g., tangible items improperly seized, or a confession obtained during an illegal detention), it does not follow that, simply because his arrest ultimately was followed by his in-court identification by the three women, there was a sufficient relationship between the two events to warrant application of the exclusionary rule. The Wong Sun Court expressly declined to adopt a “but for” test as the appropriate analytical mode (371 U.S. at 487-88, 83 S.Ct. 407), and subsequent case law uniformly has demanded more than a superficial demonstration of a causal chain between the improper act and the disputed evidence. See, e. g., State v. Miranda, 104 Ariz. 174, 450 P.2d 364 (1969) (en banc); People v. McInnis, 6 Cal.3d 821, 100 Cal.Rptr. 618, 494 P.2d 690 (en banc), cert. denied, 409 U.S. 1061, 93 S.Ct. 562, 34 L.Ed.2d 513 (1972); People v. Pettis, 12 Ill.App.3d 123, 298 N.E.2d 372, 375 (1973). It is true, however, that a sufficient connection may be found where the breach of the accused’s constitutional rights provided the government with what might be called the “opportunity for incrimination” by revealing the identity of a crucial witness [see, e. g., Smith v. United States, 120 U.S.App.D.C. 160, 344 F.2d 545 (1965); Abbott v. United States, D.C.Mun.App., 138 A.2d 485 (1958)], or, in some cases, by revealing the fact of the offense itself. See, e. g., United States v. Schipani, 289 F.Supp. 43, 61-63 (E.D.N.Y.1968), aff'd, 414 F.2d 1262 (2d Cir. 1969), cert. denied, 397 U.S. 922, 90 S.Ct. 902, 25 L.Ed.2d 102 (1970). Appellant apparently seeks an expansion of the Wong Sun doctrine in this direction. He posits that absent his arrest and detention, his identity would have remained unknown and there would have been no opportunity for the in-court identifications.5 Essentially, he argues [1068]*1068that he was the “fruit” of the police misconduct. We find this theory unacceptable.
We rejected a similar argument in Bond v. United States, supra, where it was asserted that the police had focused their investigation of a confidence game on the defendant as a result of a photograph obtained during what was alleged to have been a pretextual arrest for a traffic violation. While we concluded that the traffic arrest had resulted in no such focus, and hence there had been no “exploitation” of the alleged misconduct, we expressed doubt that the Wong Sun doctrine reached the essentially nonevidentiary circumstance of the accused’s later presence in the courtroom (310 A.2d at 224-25):
Even assuming the illegality of the prior arrest, we regard [appellant’s] position as untenable. In the first place, he points to no particular “fruit” of this alleged “poisonous tree” which was introduced into evidence against him. This doctrine does not operate so broadly as to bar all subsequent prosecutions. Rather it operates on particular evidence, either tangible or testimonial, and, if properly invoked, causes the exclusion only of such evidence. See Wong Sun v. United States, [supra]. Here, it would seem that appellant would have us hold that he himself is the “fruit” and accordingly he should have been excluded but “[w]e have ruled on more than one occasion that a court will not inquire into the manner in which an accused is brought before it, and that the legality or illegality of an arrest is material only on the question of suppressing evidence obtained by the arrest.” [Quoting District of Columbia v. Jordan, D.C.App., 232 A.2d 298, 299 (1967).]
See District of Columbia v. Perry, D.C.App., 215 A.2d 845, 847 (1966); Boucher v. Warden, 5 Md.App. 51, 245 A.2d 420, 423-24 (1968). Cf. M. A. P. v. Ryan, D.C.App., 285 A.2d 310, 315 (1971). Our conclusion rested upon the well-established principle that, given a fair trial, the fact of an illegal arrest will not vitiate a conviction. Frisbie v. Collins, 342 U.S. 519, 72 S.Ct. 509, 96 L.Ed. 541 (1952); Ker v. Illinois, 119 U.S. 436, 7 S.Ct. 225, 30 L.Ed. 421 (1886). While it is true, as appellant notes, that the Ker-Frisbie doctrine has been the subject of some criticism [see, e. g., United States v. Toscanino, 500 F.2d 267, rehearing en banc denied, 504 F.2d 1380 (2d Cir. 1974); United States v. Edmons, 432 F.2d 577, 583 (2d Cir. 1970)], we have no doubt as to its continued validity. See Stone v. Powell, 428 U.S. 465, 96 S.Ct. 3037, 3047, 49 L.Ed.2d 1067 (1976); Gerstein v. Pugh, 420 U.S. 103, 119, 95 S.Ct. 854, 43 L.Ed.2d 54 (1975); Stevenson v. Mathews, 529 F.2d 61, 63 (7th Cir.), cert. denied, 426 U.S. 954, 96 S.Ct. 3181, 49 L.Ed.2d 1193 (1976).
In Payne v. United States, 111 U.S.App.D.C. 94, 294 F.2d 723, cert. denied, 368 U.S. 883, 82 S.Ct. 131, 7 L.Ed.2d 83 (1961), the United States Court of Appeals sustained, by analogy to Frisbie, the admission of eyewitness testimony given pursuant to a confrontation which occurred during an unlawful detention, It approved, however, the exclusion of the defendant’s statement which had been made during the period of illegal custody. To support its rulings, the court relied in part upon the two Bynum v. United States decisions, 104 U.S.App.D.C. 368, 262 F.2d 465 (1958), appeal after retrial, 107 U.S.App.D.C. 109, 274 F.2d 767 (1960). In Bynum I, the court ordered the suppression of finger[1069]*1069prints obtained following an illegal arrest. Accord, Mills v. Wainwright, 415 F.2d 787 (5th Cir. 1969); see Davis v. Mississippi, 394 U.S. 721, 89 S.Ct. 1394, 22 L.Ed.2d 676 (1969). At Bynum’s second trial, the government introduced in evidence an older set of fingerprints unrelated to the unlawful arrest, and the second conviction was affirmed. We also note that the Supreme Court in United States v. Wade, supra, cited Wong Sun’s attenuation-of-taint analysis as support for its independent source rule. 388 U.S. at 241, 87 S.Ct. 1926, citing 371 U.S. at 488, 83 S.Ct. 407. We conclude that the poisonous fruit doctrine does not reach so far as to exclude identification testimony connected with an illegal arrest if, as here, there is an adequate independent source for the evidence. See Johnson v. Louisiana, 406 U.S. 356, 365, 92 S.Ct. 1620, 32 L.Ed.2d 152 (1972); Stevenson v. Mathews, supra; State v. Miranda, supra, 450 P.2d at 371-72.
Ill
Even if we were to agree with appellant that his in-court identification by the three women was causally related to his unlawful arrest in the sense contemplated by the Wong Sun doctrine, our conclusion as to the admissibility of such evidence would be unchanged. The Supreme Court has emphasized that the judicially-created exclusionary rule is not aimed at redressing the harm to an individual whose constitutional rights have been invaded, but rather seeks by its deterrent effect to preserve to the whole of society the interests secured by the Fourth Amendment.6 See Stone v. Powell, 428 U.S. 465, 96 S.Ct. 3037, 49 L.Ed.2d 1067 (1976); United States v. Calandra, 414 U.S. 338, 347-48, 94 S.Ct. 613, 38 L.Ed.2d 561 (1974). As an adjunct of the exclusionary principles embraced in Mapp v. Ohio, supra, the fruit of the poisonous tree doctrine does not mandate the automatic exclusion of all evidence which may be linked (however tenuously) to police misconduct. See Stone v. Powell, supra, 465 U.S. at 487, 96 S.Ct. at 3048. Rather, the appropriate inquiry involves an examination of the circumstances of the particular case to determine both the need for and the likelihood of deterrence of the misconduct in question should the penalty of exclusion be imposed.7 As expressed by the Fifth Circuit:
[1070]*1070Evidence should be excluded only where the benefit accruing to society from the additional deterrent against unlawful police practices equals or exceeds the detriment to society caused by the release of criminals. [United States v. Houltin, 525 F.2d 943, 947 (5th Cir. 1976). See Stone v. Powell, supra, 428 U.S. at 484-489, 96 S.Ct. at 3047-49; United States v. Calandra, supra, 414 U.S. at 348, 94 S.Ct. 613; see also Brown v. Illinois, 422 U.S. 590, 608-12, 95 S.Ct. 2254, 45 L.Ed.2d 416 (1975) (Powell, J., concurring in part)].
In the case before us, the police misconduct consisted of arresting and detaining appellant for approximately one hour on the basis of information which fell short of constituting probable cause with respect to the robberies. We do not suggest that the episode amounted to an insignificant invasion of appellant’s constitutionally protected interests. However, it is well settled that while a subsequent determination that the original arrest was made without probable cause may give rise to the exclusion of incriminating evidence resulting from the arrest, it does not provide the arrested individual with immunity from prosecution for the transaction in question. See, e. g., Bond v. United States, supra, at 224—25; Gissendanner v. Wainwright, 482 F.2d 1293 (5th Cir. 1973); United States v. Friedland, 441 F.2d 855, 861 (2d Cir.), cert. denied, 404 U.S. 867, 92 S.Ct. 143, 30 L.Ed.2d 111 (1971). While the trial court concluded that the officers did not have probable cause to detain appellant, their suspicions as to his involvement in the robberies and his possible truancy were soundly based [cf. Beck v. Ohio, 379 U.S. 89, 85 S.Ct. 223, 13 L.Ed.2d 142 (1964); Johnson v. United States, D.C.App., 349 A.2d 458 (1975); Stephenson v. United States, D.C.App., 296 A.2d 606 (1972), cert. denied, 411 U.S. 907, 93 S.Ct. 1535, 36 L.Ed.2d 197 (1973)], and he was released soon after he had been photographed and it was determined that he was not a truant.8 Cf. Gatlin v. United States, 117 U.S.App.D.C. 123, 128, 326 F.2d 666, 670-71 (1963); Wise v. Murphy, D.C.App., 275 A.2d 205 (1971) (en banc). Without more, the incident reflects good faith misjudgment on the part of the officers, scarcely warranting the severe result urged by appellant.9 See United States ex rel. Pella v. Reid, 527 F.2d 380 (2d Cir. 1975).
Appellant’s principal thrust, however, is that the gravity of the error committed by the police officers was compounded by the fact that while he was detained ostensibly for truancy, the true purpose of his detention was to gain information for the robbery investigation. At the suppression hearing, Officer Ray and Detective Ore testified that they had followed the routine procedure for truancy cases, but they acknowledged that their principal interest was in the more serious charges. We recognize that where the arrest is no more than a sham to circumvent the safeguards of the Fourth Amendment, some courts have sought to deter such miscon[1071]*1071duct by barring in-court identification testimony as well as the more direct fruits of the constitutional violation. Cf. United States v. Edmons, supra; United States ex rel. Pella v. Reid, supra.10 See also Taglavore v. United States, 291 F.2d 262 (9th Cir. 1961); Blazak v. Eyman, 339 F.Supp. 40 (D.Ariz.1971); cf. People v. Dibble, 46 App.Div.2d 829, 361 N.Y.S.2d 77, 80 (1974). However, the mere fact that by arresting an individual on one charge the officers gain an opportunity to advance their investigation of another offense does not mandate the imposition of evidentiary sanctions. In a case in which the police suspect that an individual has violated two laws, one for which they have probable cause to arrest and one for which they do not, it would be absurd to suggest that they must forego enforcement of the former simply because their primary interest is in the latter.
Appellant’s reliance on United States v. Edmons, supra, is misplaced. There, more than SO FBI agents swept a neighborhood in an effort to locate individuals who had assaulted and interfered with other agents who had been attempting to execute an arrest warrant. The officers knew only that the suspects were “young and black”, and were instructed to round up such persons on the charge of failure to have their selective service cards in their possession, in the hope that the victims of the assault would be able to pick out their assailants. Id. at 580-81. Cf. Sullivan v. Murphy, 156 U.S.App.D.C. 28, 59-60, 478 F.2d 938, 969-70, cert. denied, 414 U.S. 880, 94 S.Ct. 162, 38 L.Ed.2d 125 (1973). Five men were arrested on the pretext,11 and four were identified and subsequently convicted. The trial court found their arrests to have been illegal, but concluded that the in-court identification testimony rested upon the independent bases of the agents’ observations at the time of the assaults. The Second Circuit did not disturb this conclusion (see 432 F.2d at 582-83), but, concerned with the gravity of the agents’ misconduct, reasoned that the illegal arrests had been the “necessary cause” of such testimony and concluded that the deterrent principles of Wong Sun required that the indictments be dismissed.12
The case before us is readily distinguishable. Here there is no dragnet. Appellant’s arrest was not the result of a random or indiscriminate roundup of possible suspects. See Ellis v. United States, 105 U.S.App.D.C. 86, 264 F.2d 372, cert. denied, 359 U.S. 998, 79 S.Ct. 1129, 3 L.Ed.2d 986 (1959); People v. Lee, 84 Misc.2d 192, 375 N.Y.S.2d 812, 816 (Sup.Ct.1975). Cf. Davis v. Mississippi, supra. Although the trial court concluded that the circumstances did not provide the officers with probable cause, the record reveals that their focus on appellant was supported by the facts that (1) he was found near the scene of the recent robberies, (2) he matched the general description provided by the three victims, and (3) he was tenta[1072]*1072tively identified by the witness Dickens. Cf. Johnson v. United States, supra; United States v. Hall, 174 U.S.App.D.C. 13, 15-16, 525 F.2d 857, 859-60 (1975).
Nor was the alleged pretext upon which appellant was detained the violation of a rarely enforced statute, the investigation of which was abandoned as soon as the apprehension was effected.13 While we express no approval of the officers’ investigatory tactics, we do not view the facts as presenting the sort of egregious misconduct the deterrence of which would warrant the extreme sanction of barring the in-court identification testimony of the victims. Cf. United States ex rel. Pella v. Reid, supra, at 382-83; Paulson v. State, 257 So.2d 303, 305 (Fla.App.1972), federal habeas corpus denied sub nom. Paulson v. Florida, 360 F.Supp. 156 (S.D.Fla.1973); see also Lockridge v. Superior Court, 3 Cal.3d 166, 89 Cal.Rptr. 731, 734, 474 P.2d 683, 686 (1970) (en banc), cert. denied, 402 U.S. 910, 91 S.Ct. 1387, 28 L.Ed.2d 652 (1971).
The Supreme Court recently declared that “the policies behind the exclusionary rule are not absolute” and “must be evaluated in light of competing policies.” Stone v. Powell, supra, 428 U.S. at 488, 96 S.Ct. at 3049. Against whatever incremental deterrence arguably might be provided by barring the victims’ in-court testimony, in addition to the photographic and lineup identification which were excluded by the trial court, must be weighed the costs of such a penalty.14 See Brown v. Illinois, supra, 422 U.S. at 608-12, 95 S.Ct. 2254 (Powell, J., concurring in part).
Appellant does not seriously contend that the women’s recollections of the robberies became tainted by the fact of the illegal arrest. He does not deny that the police were aware of both the fact' of the assaults and the identities of the complaining witnesses prior to the disputed detention. Rather, he argues that but for the.detention the officers would not have learned his identity, and consequently there would have been no prosecution and no opportunity for the chain of separate circumstances to coalesce into the incriminating identification testimony.15 In the final analysis, what appellant seeks is no less than an immunity from any prosecution. On the facts of this case, such a price [1073]*1073would be too high.16 See Gissendanner v. Wainwright, supra; People v. Lee, supra. As the circuit court observed in a similar case, Payne v. United States, supra, at 98, 294 F.2d at 727:
The suppression of the testimony of the complaining witness is not the right way to control the conduct of the police, or to advance the administration of justice. The rights of the accused in a case like the present are adequately protected when the complaining witness takes the stand in open court, for examination and cross-examination.
We conclude that the trial court did not err in denying appellant’s motion to exclude the in-court identification testimony of the robbery victims.
Affirmed.