They were two men on opposite sides of the law.

Bill Rollinson was a police officer who'd fallen into the profession over a bet. While he never collected his prize — 10 bottles of beer — he quickly realised he loved the work.

"Everybody's got some good, you've just got to show them that they've got it," he says.

Brett Carhartt was a teenager, cruising around with heavy metal blaring from the speakers of his Torana. He was often pulled over by Bill.

"He was a bit of a bugger, he'd get you for anything," Brett remembers.

It was the late 1970s in Glenorchy, north of Hobart.

During one encounter, Bill did something that changed the course of Brett's life — but he didn't know it at the time.

More than 35 years on — having both survived lives that could have been easier — they've come together again, to have a conversation two men rarely get to have.

'They should have realised something was wrong'

Bill witnessed a great deal of violence during his time as a police officer. ( Supplied: Zilla Gordon )

The streets of Glenorchy were wild in the '70s, and Bill witnessed a lot of violence and death in his time — including the suicide of a young man.

Fifteen years into the job, he started to behave strangely.

At one accident he attended, Bill found himself inexplicably carrying around the severed leg of a victim, saying: "Bring out your rag and bone, bring out your dead."

"They should have realised that something was wrong then," Bill says of the police leadership.

He also developed an unhealthy addiction to the adrenaline rush of driving after an assailant.

"The moment you saw a runner and you started the car you got, not a drunk feeling, but a feeling of 'oh, that feels good'. But the moment you stopped you felt dead," he says.

Eventually he was diagnosed with post-traumatic stress disorder, and after 17 years of policing, Bill had to hang up his uniform.

A chance encounter

During nearly two decades as a cop, Bill had several encounters with Brett.

Brett's childhood had been a difficult one. His father spent time in jail and he remembers the violence at home.

"You get slapped around with the old belt and the garden hose, the jug cord," he says.

His father also tried to take his own life twice; something that still plays on Brett's mind.

Brett hated the police, until he met Bill. ( Supplied: Zilla Gordon )

By the time he was 19 Brett had seen the inside of a police cell more than a few times, and says he was also the victim of police brutality.

"They'd try to pin you with everything, they'd smack you around, give you the old phone book around the head trick," Brett says.

Brett was fuelled by anger; he hated the police.

One day when he was hooning Brett was pulled over by Bill — but he got off with a warning.

That small act of mercy had a huge impact on Brett.

Until then he thought he was headed towards a life like his father's.

But when Bill showed some faith in him, he realised he could change his ways.

Meeting again

Bill didn't know that at the time, but he does now.

A few years ago, RN's Earshot made a documentary about a policeman with PTSD and Bill got in touch with the ABC, describing his own experience.

After he'd left the force he'd started drinking more, and he had tried to take his own life.

Brett had also struggled with depression and attempted suicide —and by chance, saw Bill's comment on the ABC website.

He knew he had to reach out to Bill.

"You are a top bloke Bill, you should remember me from all those years ago. Chin up Bill and maybe we have a chat over a coffee about old times … the cop and the crim," he commented.

I decided to take up Brett's suggestion and bring the two men back together, after more than 30 years.

Around 18 months later, Brett arrived at the nursing home where Bill now lives.

Bill and Brett reunited this year after nearly four decades. ( Supplied: Zilla Gordon )

Bill looked like a bald eagle perched on the edge of his bed, his curious eyes watching everything as he waited for the knock on the door.

When it came, Bill immediately leapt to his feet, and the two men shook hands. It was the first time Brett had seen Bill out of his police uniform.

The conversation quickly turned to something important: that day that Bill let Brett off.

"You didn't know it, but you virtually taught me my ways of respect and to stop being a bloody idiot," Brett told Bill.

"You changed my history, you turned me into a better man, into what I am today."

He told Bill he'd sold his Torana, got married and had a daughter.

"It it wasn't for you, I don't know where I'd be now, because if I had have kept on going the way I did, I would have ended up in jail."

Bill says helping people was one of the reasons he joined the force.

"You're the first person who has said anything like that to me, I've never had anybody say that I've helped them and they don't know where they'd be if I hadn't saved them," he told Brett.

"Help comes in a thousand different ways, a shoulder if someone needs to talk, or a good ear, but if someone needed a good talking to I'd give it to them."

Then the conversation turned darker, to the violence they've both witnessed over the years.

Listening in, it felt like the kind of conversation men rarely get to have.

Brett told Bill: "Mate, this stuff plays on your mind, but it's actually good to talk about shit like that because it gets it out and it's not stuck in your mind."

They shared with each other that they both cry easily: Bill cries when he watches TV, Brett cries every night.

"People say real men don't cry, people who say that sort of thing have never had any trauma in their own bloody life, especially caused by other people," Bill said.

"I don't know how many times I've been told to build a bridge and get over it."

And Brett, who's been told the same thing by counsellors, replied: "I wasn't a carpenter mate."

'My kids are my world'

Bill was recently awarded a Police Integrity medal, something he says he's very proud of.

Bill was awarded a medal for his time as a police officer, but the traumatic memories of that time remain. ( Supplied: Zilla Gordon )

He still suffers from PTSD, which has numbed his emotions.

"I don't know what hate is, I don't know what love is," he says.

He copes by walking each day beside the Derwent River, next to his nursing home.

"I walk out here for tranquillity, it gets me away from thinking because you don't need to think while you walk," he says.

Brett works as a crossing guard at New Town Public School, where five of his eight children are students.

He finds that interacting with the school community, being a volunteer firefighter and working in the school canteen all help with his depression.

"What fixes me is keeping myself occupied, doing stuff I love doing. And my kids keep me going, my kids are my world," he says.

Brett left the nursing home feeling happier and lighter.

And Bill reflected that Brett is still the same person he was 30 years ago.

"He still has that same heart and I don't think you can ever take that away from anybody," he said.