By Scott Malone
BOSTON (Reuters) - Lawyers for former Boston mob boss James "Whitey" Bulger are set to challenge his 2013 racketeering conviction on Monday, contending a judge wrongly blocked them from arguing that a U.S. official had given him immunity for his crimes.
Bulger, 85, was found guilty of committing or ordering 11 murders in the 1970s and 1980s in a trial that shone a light on his corrupt relationship with federal agents and prosecutors in Boston, who turned a blind eye to the Irish-American gangster's crimes in return for information they could use against the Italian-American Mafia.
The former head of the "Winter Hill" gang currently is serving a sentence of two life terms plus five years for what U.S. District Judge Denise Casper called his "unfathomable" crimes.
His attorney, Hank Brennan, is expected to argue in the First Circuit of the U.S. Court of Appeals that Casper violated Bulger's rights by not allowing him to testify that a U.S. attorney for Massachusetts, Jeremiah O'Sullivan, who has since died, had offered Bulger immunity for his crimes, which also included extortion and drug dealing.
Casper contended that even if Bulger had been offered immunity for information on rival criminal gangs, a deal that allowed him to continue to murder with impunity would have no legal standing.
For his part, Bulger denied ever serving as an informant - or "rat" in gang parlance - contending he paid a corrupt FBI agent for information but offered none of his own.
"I've been choked off from having an opportunity to give an adequate defense and explain about my conversation and agreement with Jeremiah O'Sullivan," Bulger told Casper during his trial. "For my protection of his life, in return, he promised to give me immunity."
Federal prosecutors, represented by Assistant U.S. Attorney Randall Kromm, are expected to argue that Bulger never produced any evidence that an immunity deal existed.
"Bulger's claim that the district court violated his constitutional rights by precluding him from testifying as to an alleged immunity agreement with a federal prosecutor is meritless," they wrote in a filing ahead of Monday's hearing.
Bulger, whose brother William was the president of the Massachusetts state Senate, fled the city in 1994 on a tip that his arrest was imminent. He spent 16 years on the lam, many listed atop the FBI's "Most Wanted" list, before his capture in Southern California in 2011.
(Reporting by Scott Malone; Editing by Eric Beech)