Infamous South Boston mobster James "Whitey" Bulger will fight a 2013 jury verdict that found him guilty of committing or ordering the murders of 11 people while he ruled the city's organized crime underworld in the 1970s and '80s.

Bulger was sentenced to life in prison.

The U.S. Court of Appeals for the First Circuit on Monday said it would hear Bulger's case on July 27 in the same waterfront courthouse where a jury heard descriptions of what U.S. District Judge Denise Casper called the "unfathomable" crimes he committed while running the city's "Winter Hill" crime gang.

The 85-year-old former mobster's trial exposed his corrupt relationship with the Boston office of the Federal Bureau of Investigation, which for years turned a blind eye to the Irish-American gangster's crimes in exchange for tips it could use against the Italian-American Mafia, which was a higher-profile target at the time.

Bulger's attorneys argue that Casper made a "constitutional error" by refusing to allow them to argue that Bulger had been granted immunity for his crimes by corrupt Justice Department officials. Casper blocked him from making that claim, saying that such a deal would have had no legal authority.

Bulger terrorized Boston for decades, shooting and strangling real and perceived enemies, before fleeing in 1994 after a tip from a corrupt FBI agent that authorities were preparing to arrest him. He spent 16 years on the run, many atop the bureau's "Most Wanted" list, before being captured in Southern California in 2011.

His lawyers took an unusual approach during Bulger's trial, admitting in opening statements that their client had been an "organized criminal" and focused most of their energy on trying to prove that he had not murdered two women and that he had never served as an FBI informant, although doing so would not have been a crime.

The jury found Bulger guilty of murdering Deborah Hussey, the stepdaughter of one of his associates, but was unable to reach a verdict on whether he had killed Debra Davis, who had been dating an associate.

Bulger was sentenced to two life terms in prison, plus five years. He is currently in federal custody at a high-security penitentiary in Sumterville, Florida, according to prison records.

Bulger never testified during his trial, at one point telling Casper, "This is a sham and you do what you want with me."

(Reporting by Scott Malone; Editing by Bill Trott)