Boston mobster James "Whitey" Bulger is dead. He was found lifeless in his prison cell earlier today, apparently murdered. Bulger was the city's most notorious criminal, running a powerful gang out of South Boston for decades. He was also at the center of a longstanding mystery in the city, his whereabouts unknown for the 16 years that he spent on the run. Bulger was finally arrested in 2011, and convicted for his role in 11 murders two years later, in 2013. He was serving two consecutive life sentences and had just been transferred to a new prison in West Virginia at the time of his death. WGBH Radio’s Phillip Martin has covered Bulger extensively. He spoke with WGBH All Things Considered anchor Barbara Howard about Bulger and his death. The following transcript has been edited for clarity.

Barbara Howard: We're hearing that the inmate who may have had a hand in the death of Bulger had mafia ties. That's according to the Boston Globe. Does that surprise you?

Phillip Martin: Not at all, when you consider that Whitey Bulger had a long history of antagonism between the Winter Hill Gang, that he was formerly a member of, and his own gang, and that he came to the attention of the FBI because of their interest in taking down the Italian mob, the Mafia. He basically gained reputation and favor by working with the FBI against his enemies. By taking down the Mafia, of course, that left him more time to engage in the criminal activities that he was involved with for decades in Boston.

Howard: Talk a little bit about his rap sheet.

Martin: This is a guy who was convicted of committing multiple murders, of intimidation, of extortion. He reigned in South Boston because of his fierce reputation — his reputation for brutality. He didn’t just kill people, he slaughtered individuals.

Howard: I understand you've been talking with some of the families of his victims?

Martin: That's right. I just finished speaking, in fact, with Steve Davis. His sister Debra was believed to have been murdered by Whitey Bulger. At the trial, he was not convicted of killing Debra Davis, but it's widely believed that he killed her. They found her body in a shallow grave off of 93, not too far from where Steve Davis lives now. And Steve Davis, when asked about the death of Whitey Bulger, asked rhetorically, “Is this a trick or treat?” He wouldn't believe that this man was dead until he saw it for himself.

Howard: Bulger himself tried to come across, especially in his younger days, as being sort of a Robin Hood in South Boston. He was beloved. People wouldn't turn on him. There was a code of silence. He considered himself as savior of South Boston. He was seen as keeping drugs out of that neighborhood, but that was all smoke and mirrors — is that right?

Martin: Totally smoke and mirrors, and he succeeded in conveying that message, at least to a lot of people. This man was actually bringing drugs into the neighborhood and profiting from keeping his enemies and competitors out of the neighborhood by in fact developing this reputation for being a Robin Hood. But a Robin Hood he was not.

Howard: Another thing Bulger prided himself in was not being what he called "a rat."

Martin: That's right. Interestingly, this is no doubt one of the factors that probably led to his death. Once you are known as a rat, it's perhaps one of the worst reputations you could have in prison and on the streets. So he fought hard to build his reputation as a ruthless, fearless, fearsome and even loathsome person. But to be a rat was the last thing in the world he wanted to be. And he did all he could do to erase that image from the minds of jurors and from the public during his trial.

Howard: But his handler, John Connolly of the FBI, who grew up in the same housing development in Old Colony in South Boston — it was John Connolly who ended up going to prison over that.

Martin: Well that's right. You had the proof right in front of you, the evidence that came out in court, that he in fact was an informant.

Howard: Whitey Bulger didn't like disloyalty. He didn't like people who snitched. He didn't like rats, but he himself was a rat.

Martin: He was a walking contradiction. He himself was a rat. It was proven in court that he was a confidential informant.