On the state of the evidence disclosed by the substitute bill of exceptions, the inquiry which the defendant was precluded (despite the fact that the Commonwealth had raised no objection) from putting to the complaining wit*880ness on cross-examination related not merely to the credibility of the latter but to the central issue of the correctness of the identification of the defendant as one of the smaller group which committed the crime, an issue which was not obviated by the defendant’s admission that he was part of the larger group in the vicinity. In these circumstances it was error to foreclose inquiry on cross-examination into the content of the written description which led to the apprehension of the defendant and the subsequent in-person identification of him by the complaining witness. See Commonwealth v. Franklin, 366 Mass. 284, 290 (1974), and cases cited; Commonwealth v. Graziano, 368 Mass. 325, 329-330 (1975); Commonwealth v. Bohannon, 376 Mass. 90, 94 (1978); Commonwealth v. Dominico, 1 Mass. App. Ct. 693, 712 (1974), and cases cited.
Joseph M. Flak for the defendant. Robert J. Schilling, Special Assistant District Attorney, for the Commonwealth.Exceptions sustained.