It's tough to be in prison, but to grow old in prison can be especially difficult. Jenifer McKim from WGBH News partner the New England Center for Investigative Reporting has been looking into the issue. She spoke with WGBH's All Things Considered host Barbara Howard. The following transcript has been edited for clarity.

Barbara Howard: I know you say it's not just the aches and pains of aging, but some real dangers.

Jenifer McKim: Yes. We've been looking at the issue of this growing population of aging inmates in Massachusetts. The numbers are pretty stunning. The numbers of older people, 55 and older, have grown more than 32 percent over the last eight years. And with this come all of these issues and complications related to their care, but also vulnerabilities and safety risks. There's only been five deaths in Massachusetts state prisons since 2000, but three of them have been older men. And nationally, statistics show that older inmates are twice as likely to be killed in prison than other folks. So there's definitely some issues.

Howard: You said some sort of video came to your attention that really casts that in sharp relief?

McKim: So we obtained a surveillance video of a murder in the state's maximum security prison, Souza-Baranowski, in 2014. The film showed a 72-year-old man, William Sires, walking with a cane in the middle of the afternoon. First he gets into an altercation with an inmate where they start to talk, and then the inmate kicks him, and he starts to hit him with the cane. It's broken up by some other inmates, and he continues walking around the tier again. A couple minutes later, he's dragged into a cell by a different inmate. Another inmate closes the curtain, and then the cell of the door closes shut. We understand through court records that somebody called out to the guard to shut the door, and he did so without understanding exactly who asked him to do it or why. William Sires was then left in the cell for 30 minutes with his killer before he was discovered.

Howard: How old was he?

McKim: He was 72 years old.

Howard: And how old were the men who ostensibly killed him?

McKim: So he was physically killed by Michael Freeman, who was about half his age. And the two other men who were convicted in their roles for his killing were also much younger than him. You can see in the tier that he is just at a totally different age from the other men in this block.

Howard: The guard who shut the door, why wouldn't he come see why the door needed to be shut if they were calling for it?

McKim: So in testimony, he mentions that it's completely normal practice for guards to open and shut doors on the request of inmates who perhaps want to use the bathroom and have some privacy, and that he didn't know who had asked him, and didn't check to see.

Howard: Tell me a little bit more about Sires.

McKim: So Sires was convicted of a 1973 murder of his mother. From what we hear from transcripts and interviews, he was not well-liked in prison. He was buried in the state cemetery for inmates who have no family to collect their bones. So in fact, there's really nobody out there crying for any questions about what happened in his death, and nobody there to speak for him.

Howard: His death came 10 years after the strangulation death of a convicted pedophile priest, John Geoghan, but didn't get any similar publicity as John Geoghan's case.

McKim: It's very interesting, because when Sires was murdered, it really was a case against the men who killed him without the focus on what happened. In contrast, John Geoghan was killed about 11 years beforehand, and it was a huge issue in the state of Massachusetts. He was strangled in the same maximum security prison, in a cell, by a man. There was only one guard also in the tier at the time, and there were huge issues when that happened - questions about how he could have been left there to be murdered. And there was a big shakeup in the Department of Correction when that happened - a 130-page list of recommendations of things that they should do to fix, particularly, Souza-Baranowski. There were issues about not leaving one guard in a tier by himself. There were also issues and questions about putting an older man in the maximum security prison.

Howard: Have any of the suggestions been implemented?

McKim: So my understanding is that there were some changes, and that there were others that weren't. And that time passes, and when something sort of falls out of the media's eye, things kind of devolve back to normal. I spoke with one lawyer who was involved in the Geoghan murder investigation to look at what happened. I talked to him about what happened with Sires, and he said 'well, this is really important to bring this out again, because it takes something like this to look at it again.'

They say that prison is not an old man's game. A lot of the older folks stay in their cells, afraid of what is really often a gang-filled community. Not everybody is sympathetic to people who are in prison, and there are a lot of people who believe they're exactly where they should be. But there are particular issues about the state also protecting the folks in their care.

Howard: OK, thanks Jenifer.

McKim: Thank you very much

Howard: That's Jenifer McKim from WGBH News partner the New England Center for Investigative Reporting, talking about the dangers - some of them fatal - of aging in prison. This is All Things Considered.