Edward (Big Ed) Johnson is not physically large. In fact Mr. Johnson, who is serving a life sentence for gang-related homicide, looks wispy standing next to some of his fellow inmates. The origin of his nickname is likely wrapped up in the fact, as a convict at Donaldson Correctional Facility, Alabama’s highest security prison, he was a gang-leader in a prison populated by violent criminals.

That is, until taking part in the Vipassana Buddhist meditation program that forms the centerpiece of the documentary The Dhamma Brothers.

“I had to go tell gang members, ‘You go your way, I’m going to go my way,’ and hope I don’t catch any repercussions behind that,” says Mr. Johnson in the film, recalling how the experience caused him to leave the prison reprisal culture behind.

On the third day of the 10-day Vipassana course —­ held uninterrupted in the prison gym — Mr. Johnson had a heart-wrenching revelation, consciously acknowledging that his daughter, who suffered a fatal fall from a swing-set while he was in prison several years earlier, was dead. Despite attending her funeral, in shackles, he had never accepted her death.

“He looked down at her in the ground and believed he saw her eyelids twitching,” says Jenny Phillips, a Concord-based cultural anthropologist and prison psychotherapist who, inspired by the Donaldson inmates she met during a research trip in 2000, decided, with no filmmaking experience, to make this documentary.

“He went up to [meditation teacher] Bruce Stewart and said ‘I had a dream my daughter is dead,’” says Mrs. Phillips, “and Bruce, being a psychotherapist, said ‘That’s great! You’re doing good work.’ But that made him happy.”

Filmed again in 2006, calmly dispensing wisdom and sharing personal insight, Mr. Johnson is one of the film’s most arresting portraits of change. “Some people is scared to deal with life,” says Mr. Johnson. “I was one of those people scared to deal with life.”

But there are several such stories of transformation to The Dhamma Brothers, including its own. Mrs. Phillips acknowledges the film went through several “final cuts,” from 2004 through 2007, all presenting a far bleaker outlook than the version that opens the Martha’s Vineyard Film Festival next Friday night.

“It was certainly very realistic,” deadpans Andy Kukura the documentary’s editor, Boston based, remembering the downbeat finale of the original 2004 cut. “We had footage of the men breaking down the apparatus in the gym — taking down tarps, folding up the beds — with a voiceover saying how the warden had called a halt to meditation,” says Mr. Kukura, who fashioned today’s finished documentary from 100 hours of footage.

Acting on a letter of complaint from the prison chaplain, who was losing inmates to this nonreligious practice, then-warden Stephen Bullard called an end to the regular group meditation. After a change in administration in 2005, meditation was reintroduced. Mrs. Phillips, the Vipassana teachers and film crew also were given further access to the prison, allowing the team to flesh out the film with the inmates’ testimony.

Mr. Bullard, Donaldson warden until 2005 is interviewed in the documentary; he advertises his scepticism as to the scope for reform within his prisoners.

“Is it something they can fake for their final assessment in front of the parole board?” he asks in the film. “Show me you’re still doing it in five years, show me when you’re out.”

Mrs. Phillips maintains that the prisoners’ testimonies are genuine. “There’s not much to gain by saying they didn’t do it to me,” she says.

She is particularly surprised by their determination during the intervening years; they were able not only to maintain interest in the program but to progress independently.

“It’s hard to keep anything going in prison,” she says. “It has all the distractions of a shopping mall with the added elements of depravation, fear and danger. It’s a very stimulating environment.”

Among a cast of characters whose crimes include a drive-by murder and a horrific stabbing, Wayne Finch’s story stands out to her.“This is a man who is a serious gang-banger,” says Mrs. Phillips, who has decided not talk about the specifics of Mr. Finch’s past, but cites his as a particularly compelling Vipassana story. “He has a background of such incredible violence. But [following the 10 days] he continued to navigate through prison in a more peaceful way.”

Mr. Finch talks briefly at the end of the film about his experience.

“I practice on and off. It’s been a real struggle me being in the blocks,” he says. “There’s a lot goes on within the system and sometimes I’m kind of caught up in the mix of it. But since I did the 10 days, it humbled me a lot.”

Mrs. Phillips cites recent Pew research showing that a full quarter of the world’s prison population exists in America. Donaldson itself was suffering from serious overcrowding during Mr. Bullard’s tenure. In a country where one in every 100 Americans is incarcerated, with a high national rate of re-offense, focusing on prisoner rehabilitation should be a priority.

“You have to look at cost-effectiveness to avoid recidivism and at the public safety issues to not send unrehabilitated prisoners back on to the street,” she says.

Mr. Kukuru, who has never done meditation, argues the film is not soft on its subjects. “[It] doesn’t shy away from describing their crimes. They’re not exonerated ... it just stresses the need for treatment.”

Mrs. Phillips hopes the film can help alter perceptions. “The public diet is MSNBC’s Lock-Up, people walking around with huge torsos and tattoos on the their necks with Crips and Bloods and neo-Nazis everywhere,” she says. “The truth is it’s a very vulnerable population.”

The Dhamma Brothers screens Friday, March 14, at 7 p.m. followed by discussion with Mrs. Phillips at the Chilmark Community Center.