BOSTON — Federal prosecutors are granting immunity to five men in a decades-old slaying involving New England’s former mob boss.

WPRI-TV reports ( that four of the men are Rhode Islanders with mob ties: Charles “Harpo” Garabedian, Richard Cinquegrana, William Ricci and Joseph DeLuca.

Another man, Roland Wheeler, is also named, according to a document filed in Boston federal court Friday listing evidence in the case against Francis “Cadillac Frank” Salemme.

The former Patriarca crime family boss and associate Paul Weadick have been charged in the 1993 killing of former Boston nightclub owner Steven DiSarro, whose remains were found in March behind a Providence, Rhode Island mill building owned by Ricci.

U.S. Attorney Carmen Ortiz’s office and the attorneys for Salemme and Weadick, who have pleaded not guilty, declined to comment Saturday.