He spent more than 40 years in prison but just 18 months after finally being released, Bobby Veen has died at the age of 62.

Veen was one of Australia’s longest-serving prisoners, sent to jail for the killings of two men in separate incidents in the 1970s and 1980s.

He died of a heart attack on Saturday on the New South Wales Central Coast.

Veen had been living with his adoptive sister, Bernice, since his release in 2015 and speaking to Lateline after his death, she described him as “the kindest, gentlest person”.

“In the end he only got 18 months of freedom after spending 40 years in jail,” she said.

Veen spoke to Lateline last year about growing up as a member of the Stolen Generations and the abuse that he said led him to crime.

Born in Bourke, he was taken from his Aboriginal family as a baby and later adopted by the Veen family of Albury.

“They were a beautiful family and I was raised up good. My father was stern, strict. My mother used to take us to church every Sunday,” he said.

But when he was 11 years old, Veen said he was abducted and molested by three men.

This sent him on a downward spiral that saw him end up in a boys home, and eventually working as a prostitute on the streets of Kings Cross.

He was found guilty of manslaughter over the stabbing death of a man in 1975, and after being released from prison for that crime, he murdered another man in 1983. He claimed both men were paedophiles.

Despite being due for parole in 2003, Veen was not released from prison until June 2015, when doctors diagnosed him with cancer.

“It’s the strangest feeling I’ve ever had, very daunting, emotional too,” he said.

By that time he had served in many of the New South Wales’ prisons, including Goulburn, Long Bay and Parramatta jail.

“He should have got out in 2003 when he was first eligible for parole. He was not a danger to anybody,” Bernice said.

“He believed the two people he killed were paedophiles.”