“Brooklyn is an outlier — the resources and the number of cases they’re taking on have no parallels,” said Samuel R. Gross, a University of Michigan professor who runs the exonerations registry.

In the first six months of this year, the Brooklyn district attorney’s office vacated the convictions of six men, earning praise from defense lawyers and prisoners’ advocates. But not every case will turn out that way; this week, the office intends to announce that it plans to stand by 11 of the convictions obtained by Mr. Scarcella.

“Detective Scarcella played a very small role in these cases, did not generate an incriminating statement from these defendants, and in many cases, the defendants themselves don’t allege the detective or the prosecutors did anything wrong,” Mr. Thompson said.

When Mr. Thompson took office, there were two lawyers on the review unit; he has since assigned 10 assistant district attorneys and three detective investigators to it.

Ronald S. Sullivan Jr., a Harvard Law professor who directs the criminal justice institute there, is a consultant to the district attorney on the design and operations of the unit; a panel of three independent lawyers reviews the unit’s recommendations before Mr. Thompson makes the final decisions. The effort costs $1.1 million a year.

In the six cases that Mr. Thompson’s office has vacated so far, the unit found fairly solid evidence showing the men should not have been convicted. Two were overturned based on DNA evidence; three because the testimony of a crack-addicted witness who was frequently used by Mr. Scarcella was discredited; and the sixth was based on a receipt and police reports showing that the defendant was, as he had always claimed, in Florida during the murder.