He was once a national and global hero winning a gold Paralympic medal and competing also in the Olympics. These days Oscar Pistorius is serving a life sentence in South African for murdering his girlfriend.

But he become a spiritual leader and is preaching the Bible to hardcore criminal inmates at his prison near the capital Pretoria, his father has told the UK newspaper, The Times.

The former athlete is serving a life sentence for the 2013 murder of his model girlfriend Reva Steenkamp, aged 29, is now the leader of a bible group at the Atteridgeville correctional center in Pretoria.

Throughout the world he was known as the Blade Runner due to his hi-tech carbon prostheses,

He has found new purpose since being jailed for life for the murder of his girlfriend, Henke Pistorius said.

He told The Times that his son had "always been a child of God" and was "making a difference to others" within the prison walls.

"I have no doubt that Oscar has changed the environment in the prison for the better, he is helping to mediate between people and is having a positive influence," Pistorius said.

"He can feel he is making a difference to others who really needed a difference to be made — to give their lives meaning, purpose and some hope. As a result, things have also improved for him. It's a wonderful story.

"They are hardcore chaps, the problem people in the prison, but now they are all meeting to follow the Bible once or twice a week."

December marked the second Christmas that Pistorius has spent behind bars. He still must serve another five years before he is eligible for parole in 2023.

Oscar Pistorius is a double amputee and he fired his 9 millmeter pistol through a locked lavatory door at his home in 2013, killing Reeva Steenkamp, a law graduate and model.

Britain's Daily Mail cited South Africa's Weekend Argus newspaper quoting a source in South Africa's Department of Correctional Services who claimed Pistorius was a model prisoner who was "humble and caring."

The source said: "The Oscar I've come to know in jail is kind-hearted and cares for his fellow inmates. He buys food for those who can't afford it or those who are far away from their relatives. And he does this without asking for anything in return.

"Oscar also doesn't deny what he did and shows remorse every day without faking it or to manipulate people's opinions. This is the side he shows in jail and people should stop judging him."

The source said that Pistorius keeps a low profile behind bars and did not enjoy any preferential treatment adding: "He likes his privacy and spends a lot of his time reading and visiting the prison library. He's a real bookworm."

The Blade Runner was the first double amputee to race in the Olympics competing in the 2012 London Games and became a worldwide role model.

But the following year Pistorius plummeted from grace after being arrested for the brutal murder of Reeva shooting her four times including a fatal wound to the head.

Reeva's parents British-born June and her South African-born retired horse trainer husband Barry, 75, were always convinced she was murdered.

The couple told a TV channel that they believe Reeva had packed her bags and told Pistorius she was leaving him on the evening of her death and that he killed her.