The murder trial of South African paralympian star Oscar Pistorius has resumed for a fourth day in Pretoria.

His defense lawyer is cross-examining witnesses who say they heard a screaming on the night in February 2013 when he shot dead his girlfriend  Reeva SteenKamp.

The double amputee denies intentionally killing her, saying he mistook the 29-year-old model for an intruder.

If found guilty, the 27-year-old could face life imprisonment.

Defense lawyer Barry Roux said that the two neighbours, Michell Burger and Charl Johnson, had discussed testimony with each other and amended the rough notes they had made a few days after the shooting.

“Your interpretation (of events) is designed to incriminate the accused and it’s unfortunate “, said Mr Roux.

Mr Johnson denied this. He insisted that he heard a  woman screaming “help” followed by a man doing the same.