The trial judge erred in ruling that there was probable cause to arrest the defendant. See Sibron v. New York, 392 U.S. 40, 62 (1968). See also Commonwealth v. White, ante 929, 930 (1981). Passing the question whether the policemen's actions in stopping and detaining the defendant were "based on specific and articulable facts" (Terry v. Ohio, 392 U.S. 1, 21 ; compare Commonwealth v. Wainio, 7 Mass. App. Ct. 863 ), we conclude that at the time the defendant was placed in the cruiser he was "under arrest." See Commonwealth v. Wallace, 346 Mass. 9 , 16 (1963). See also Commonwealth v. Garcia, 379 Mass. 422 , 427 (1980). This arrest or seizure (see Terry v. Ohio, supra at 16) was unlawful because "at that moment the facts and circumstances within [the officers'] knowledge and of which they had reasonably trustworthy information were [not] sufficient" to constitute probable cause to arrest the defendant. Beck v. Ohio, 379 U.S. 89, 91 (1964). Compare Brown v. Texas, 443 U.S. 47, 50-52 (1979). Only the defendant's ethnicity and rate of movement were apparent to the officers at the time of the stop. Neither race nor velocity (or both) provided a reasonable ground to suspect that a crime had been committed, was in progress, or was about to be committed. Compare Commonwealth v. Bacon, 381 Mass. 642 , 646-647 (1980). Moreover, we are not able to discern any justifiable basis for the police officers' driving the defendant around the area. As the officers had no knowledge or information at that juncture (even after checking with the dispatcher at the operations control center) of any crime the defendant might have committed, we conclude that there was not then available to the police sufficient "information which reasonably permit[ted] a conclusion that the defendant ha[d] probably committed a felony." Commonwealth v. Andrews, 358 Mass. 721 , 723 (1971). See Henry v. United States, 361 U.S. 98, 101-102 (1959). Contrast Commonwealth v. Pellier, 362 Mass. 621 , 626 (1972); Commonwealth v. Snow, 363 Mass. 778 , 788-789 (1973).
As the judge improperly concluded that the police "had probable cause to detain the defendant" at the time of the initial stop, we are constrained to remand this case to the Superior Court for a determination whether the in-court identification was obtained by official "`exploitation' of the `primary illegality' within the meaning of Wong Sun [v. United States, 371 U.S. 471, 487-488 (1963)]." United States v. Crews, 445 U.S. 463, 469 & n.9 (1980), quoting from Maguire, Evidence of Guilt 221 (1959).
Accordingly, the judgments of conviction are reversed, the verdicts are set aside, and the case is remanded to the Superior Court for reconsideration of all aspects of the identification issues in light of this opinion. See United States v. Crews, 445 U.S. at 470-474. Prior to a retrial, the judge
must make findings of facts and rulings of law as to the validity of any proposed in-court identification pursuant to the teachings of Commonwealth v. Venios, 378 Mass. 24 , 26-28 (1979). Cf. Commonwealth v. Powell, 10 Mass. App. Ct. 57 , 60-61 (1980).