Historic Irish mob boss James (Whitey) Bulger tipped off former New England mafia boss Francis (Cadillac Frank) Salemme to the fact that Salemme’s business partner, Stevie DiSarro, was cooperating with the feds in the weeks before DiSarro was slain 25 years ago, according to an allegation in new court filings citing an FBI informant. Salemme is going on trial this week for DiSarro’s murder. In the early 1990s, Salemme and DiSarro co-owned The Channel nightclub on the South Boston harbor. The FBI informant told one of his handlers in a 2016 phone conversation that in the spring of 1993, Bulger and his right-hand man Stevie (The Rifleman) Flemmi, alerted Salemme that DiSarro had flipped and already testified in front of a federal grand jury about his knowledge of Salemme’s affairs. DiSarro disappeared on the afternoon of May 10, 1993. Prosecutors say that was the day Salemme watched on as DiSarro, 44, was strangled to death inside Salemme’s suburban Boston home by his son, Francis (Frankie Boy) Salemme, Jr. and Salemme, Jr.’s best friend, Paul (Paulie the Plumber) Weadick, a convicted murderer and longtime Boston mob associate. DiSarro’s remains were found in Providence in March 2016 and four months later, Salemme, 84, and Weadick, 62, were arrested and charged in the hit. Cadillac Frank, who led the New England mafia in the first half of the 1990s before joining Team U.S.A. by the end of the decade, was living in the Witness Protection Program when the feds came calling, already having pled guilty to perjury and obstruction of justice connected to the DiSarro investigation. Salemme, Jr. died of complications arising from the AIDS virus in 1995. While heading the Patriarca crime family, the half-Irish Salemme aligned himself with Bulger and Flemmi, the most powerful gangland figures in South Boston at the time. They had all come up together in the turbulent Boston underworld of the 1960s — Cadillac Frank and Flemmi were childhood best friends. Prior to Salemme taking the reins of the city’s Italian crime syndicate, Bulger had butted heads with his predecessors. One of the most iconic American criminals of the past half century, Bulger ran the Winter Hill Gang, Beantown’s Irish mob, out of a tavern in “Southie.” But secretly, he was on the FBI’s payroll, too. Bulger and Flemmi maintained an intelligence exchange with disgraced FBI agent John Connolly for 20 years prior to them all getting busted in the 1990s and Bulger spending 16 years as a fugitive. Bulger, 88, was caught in 2011 and soon convicted of 11 murders. Connolly was convicted of second degree murder for tipping off Bulger to the identity of an FBI informant who Bulger had killed in Florida in 1982. He was suspected of aiding Bulger in other gangland slayings as well. The relationship between Bulger, Flemmi and Connolly was depicted in the 2015 film Black Mass, starring Johnny Depp as Bulger and Joel Edgerton as Connolly. Flemmi turned government informant in 2003 and testified against both Bulger and Connolly at their respective racketeering and murder trials. He told the FBI in his debriefing session that he accidentally walked in on Salemme, Jr. and Weadick killing DiSarro in 1993 at the Salemme residence. As recently as 2013, Salemme told the FBI that Flemmi was the one who murdered DiSarro. Bulger and Flemmi owned a small piece of The Channel after arranging for rezoning and licensing for the club from their contacts in South Boston city hall upon DiSarro and Salemme purchasing the establishment in 1991. Attorneys for Weadick filed a motion in court last week trying to get clarification on Flemmi’s future testimony at this month’s trial and how it jibes with a piece of law enforcement documentation from the 2000s. Flemmi asserted in his debriefing that DiSarro was killed in the Salemme’s kitchen, however Weadick’s lawyers are of the belief that a 2007 report written by an FBI agent cites a confidential informant divulging that he was told by Salemme, Jr. before he died that the DiSarro hit went down in the basement to avoid his mother from knowing what was going on. Per that informant, Cadillac Frank’s wife and Frankie Boy’s mom was upstairs in the master bedroom at the time of the murder.