OUAGADOUGOU -- When Pierre Owono was 25, he was sentenced to four years in a Cameroonian jail for robbery. But the justice system misplaced his file, he had no money to hire a lawyer, and so he remained behind bars for 33 years.

He finally walked free last August at age 58, thanks largely to a documentary on his life, which premiered this week at the Fespaco Panafrican Film Festival in Ouagadougou.

The director of "Au Dela De la Peine," which loosely translated means too much punishment, said she wanted to make a film about the death penalty in Cameroon, but instead stumbled upon Owono's story by accident.

"I was shocked and saddened when I heard about Pierre," Osvalde Lewat, whose film is up for a prize in the documentary category, told AFP in an interview.

"He came from a very poor family who turned their backs on him -- they were ashamed to see him in jail for so long.

"And Pierre didn't have any money for a lawyer, so he was completely on his own" in pursuit of justice, she said.

Lewat said however she did not aim to expose gross injustices in the Cameroon justice system -- she is not a prison expert -- but wanted to tell a compelling story which would spur people to think.

"I'm someone who refuses to teach lessons to others, my aim is to look at certain things in life. I ask everyone 'take a look at this with me' and they can then draw their own conclusions and form their own opinion," she said.

The reactions at Fespaco have been strong. The audience gasped several times during one screening, while loud applause greeted the end of the film.

Authorities cooperated closely with the director, allowing her camera into a Yaounde Jail for hours at a time, a fact she put down to her wish to honestly portray life behind bars for one individual.

The film also includes interviews with his now ex-wife, son and daughter, who only reluctantly agreed to talk to the filmmaker, and whose pain and anger is clearly visible.

On his last day in prison, the camera is right by his side as he uncertainly walks through the gates and onto a road to catch a taxi.

suddenly his face breaks into a broad grin.

Lewat then accompanies him home, first to a cold welcome by his family and then to his village, where in marked contrast cries of joy greet him as he walks into town.

Before the film was even finished, Cameroonian media heard about the story and ran several reports on the long-lost prisoner. Shortly thereafter, the prison administration inspected a number of jails around the country.

Several other inmates, locked up for years because of similar mix-ups, were then released. The events pleased Lewat. "I think this film can give a little something to other Cameroonian prisoners, it has already started to do just that." (AFP)