The trial of South African Paralympic champion Oscar Pistorius opened in Pretoria on Monday. The Blade Runner denied murdering his girl friend Reeva Steenkamp but his neighbor Michelle Burger told the court that she heard a woman screaming and a man shouting.

A neighbor of South African Olympian Oscar Pistorius has testified she heard a woman's screams before the sound of four gunshots on the day Pistorius shot and killed his girlfriend on Valentine's Day of last year.

Michelle Burger has told Pistorius' trial she and her husband were awoken by screams in the pre-dawn hours when Pistorius killed Reeva Steenkamp by shooting four times through a door in his bathroom.

"My lady what I can say to the court is her shouts, her screams were petrifying. Before the gunshots, moments before the gunshots I sat in the bed and it's the most helpless feeling I've ever had in my life."

Pistorius has pleaded not guilty to the charges of murder.

He contends he killed Steenkamp by mistake, thinking she was an intruder in his house.

The trial is being broadcast live on television throughout South Africa.

If convicted, Pistorius could be imprisoned for at least 25-years before any chance of parole.

The double-amputee became famous after qualifying to compete at the London Olympics.

He also has six Paralympics gold medals.

The trial in Pretoria will continue later today.