Former Boston crime boss James "Whitey" Bulger is appealing the racketeering conviction that landed him a life sentence last week.

Bulger's attorneys filed a brief notice of appeal in federal court late Wednesday. 

The appeal was expected. Bulger's lawyers have said he believes his trial was a "sham" because he wasn't allowed to argue that a now-deceased federal prosecutor gave him immunity to commit crimes.

The Winter Hill Gang boss was an FBI informant against the rival New England Mafia.

Bulger was convicted in August in a broad racketeering case, including 11 killings and other gangland crimes in the 1970s and 80s.

Bulger fled Boston in 1994 after being tipped off by a former FBI agent he was about to be indicted. He was a fugitive for 16 years until he was captured in 2011.

Read more about the trial of James "Whitey" Bulger here