In an April 8 interview with John Catsimatidis on his New York radio show, Mr. Dershowitz asserted that Mr. Mueller was “the guy who kept four innocent people in prison for many years in order to protect the cover of Whitey Bulger as an F.B.I. informer.” Mr. Mueller, he said, was “right at the center of it.” Mr. Bulger was a notorious crime boss in Boston, the head of the Winter Hill Gang, and also a secret source for the F.B.I.

There is no evidence that the assertion is true. I was the federal judge who presided over a successful lawsuit brought against the government by two of those men and the families of the other two, who had died in prison. Based on the voluminous evidence submitted in the trial, and having written a 105-page decision awarding them $101.8 million, I can say without equivocation that Mr. Mueller, who worked in the United States attorney’s office in Boston from 1982 to 1988, including a brief stint as the acting head of the office, had no involvement in that case. He was never even mentioned.

The case wasn’t about Whitey Bulger but another mobster the F.B.I. was also protecting, the hit man Joseph Barboza, who lied when he testified that the four men had killed Edward Deegan, a low-level mobster, in 1965. Mr. Barboza was covering for the real killers, and the F.B.I. went along because of his importance as an informant.