Notorious Boston mob boss James ‘Whitey’ Bulger was found dead at a federal prison in West Virginia on Tuesday. He was 89.

After an investigation, authorities said Bulger was murdered inside the prison a day after being transferred from another facility. Bulger was the feared former leader of Boston’s Irish-American Winter Hill Gang, and killed or was responsible for the assassination of almost 20 people between 1973 and 1985, per federal investigators. He controlled much of Boston’s criminal activities during that time.

After spending 16 years as one of the country’s most wanted fugitives, Bulger was arrested by the FBI in Santa Monica, California, in 2011 after the bureau received a tip. In 2013, he was convicted for his involvement in 11 murders in various states. The gangster had been serving a life sentence in prison.

Bulger’s girlfriend Catherine Greig was arrested alongside him in June 2011. Federal agents found $822,000 in cash in the couple’s apartment at the time of the arrest, as well as several fake identity documents and a collection of firearms. Greig, who is now 67, pleaded guilty in 2012 to identity fraud and harboring Bulger, according to NBC News. She is currently serving a nearly ten-year sentence in a federal prison in Minnesota.

Bulger’s criminal activities started at an early age. He was held in a juvenile detention center and was discharged from the Air Force in 1952 after multiple run-ins with the law.

50 CELEBRITIES WHO DIED IN 2018 – TRIBUTE SLIDESHOW

The gangster also inifiltrated the FBI and several other government agencies, and his other crimes included racketeering, extortion and money laundering.

Bulger’s brother William Bulger is a retired politician who was the Massachusetts state Senate’s longest-serving president.

Johnny Depp portrayed Bulger in the 2015 biographical crime drama Black Mass, which also starred Joel Edgerton, Benedict Cumberbatch, Dakota Johnson and Kevin Bacon. The film is based on a book of the same name by Dick Lehr and Gerard O’Neill.

Bulger was the inspiration behind Jack Nicholson‘s Irish mob boss character in Martin Scorsese‘s Oscar-winning 2006 film The Departedwhich also takes place in Boston.