When the Brooklyn district attorney’s office asked a judge last month to toss out the guilty verdict of a man who had been wrongfully convicted of murder, the prosecutors making the request did something they rarely do: They held someone responsible for bungling the case.

It was July 12 and Mark Hale, the chief of the office’s Conviction Review Unit, announced in court that the wronged defendant, Jabbar Washington, had spent 20 years in prison because of grievous errors at his trial. But then, Mr. Hale went further, telling the judge that the prosecutor who had overseen the trial intentionally withheld evidence and coaxed a witness into giving testimony that was purposefully misleading.

“There’s a lot of — perhaps blame is maybe the wrong word — but responsibility that goes around on that,” he said.

It might seem like an obvious step for prosecutors seeking to reverse a tainted conviction to declare in open court who in law enforcement had a role in compromising the case. But assigning blame, at least in public, doesn’t happen often — even in troubled cases.