A gangster in U.S. custody after 16 years on the run has pleaded not guilty to charges he committed 19 murders.

Observers said James “Whitey” Bulger spoke quietly but clearly as he entered his plea Wednesday in a federal court in Massachusetts, accompanied by his public defender.

Relatives of the murder victims sat in the courtroom audience alongside Bulger's brothers, including William Bulger, who once was the president of the Massachusetts senate.

Also in the courtroom were law enforcement officers who participated in the long-running investigation against Bulger. One retired state policeman, Tom Foley, said it was a relief to finally see Bulger in handcuffs.

The 81-year-old Bulger was leader of the violent Winter Hill Gang in Boston, a largely Irish mob that ran criminal ventures. Authorities offered a $2 million reward for his capture and he rose to number one on the FBI's 10 Most Wanted list after the death last month of al-Qaida leader Osama bin Laden.

Bulger once was an FBI informant. He provided the law enforcement agency with tips about his gang's main rival, the New England Mob.

His legend as a fugitive grew over the years. Many books have been written about him, and he was the inspiration for a character played by actor Jack Nicholson in the 2006 film, “The Departed.”

The arrest of Bulger and his long-time girlfriend, 60-year-old Catherine Greig, came less than two days after the FBI sparked new interest in the case by using a 30-second television ad aimed at women around Greig's age, to determine her whereabouts and ultimately his.