BOSTON — Former New England Mafia boss Francis “Cadillac Frank” Salemme and a mob associate have been indicted in the 1993 killing of a Boston nightclub owner.

An indictment unsealed Friday charges Salemme and Paul Weadick with the murder of federal witness Steven DiSarro.

Salemme was arrested last month in the case and is being held without bail. Weadick was arrested Friday and pleaded not guilty to the charge during a hearing in U.S. District Court. He was ordered held in custody pending a detention hearing scheduled for Sept. 8.

The indictment alleges that Salemme, Weadick and Salemme’s son participated in DiSarro’s killing to prevent him from talking to authorities about illegal activities by Salemme and others. Salemme and his son, Frank Salemme Jr., had a hidden interest in DiSarro’s nightclub, The Channel. Weadick, 61, of Burlington, was a close associate of Salemme’s son, according to the indictment.

Salemme, now 83, led the New England family of La Cosa Nostra in the early 1990s. His son died in 1995.

The indictment says shortly after DiSarro was killed, Salemme brought his body to Providence, Rhode Island, where his associates made arrangements to bury it. DiSarro’s remains were found in March behind a mill in Providence.

Salemme denies participating in DiSarro’s killing. Weadick’s lawyer, Carmine Lepore, said Weadick had “absolutely nothing to do with” DiSarro’s murder. Salemme was indicted on racketeering charges in 1995 and convicted in 1999. He was indicted again in 2004 for denying knowing anything about DiSarro’s killing while he was negotiating a plea deal with federal prosecutors. He was convicted of obstruction of justice and sentenced to five years in prison.

Salemme went into the federal witness protection program while he was a cooperating witness during the prosecution of Boston gangster James “Whitey” Bulger and former FBI Agent John Connolly Jr., Bulger’s handler while he worked as an FBI informant.