Ex-girlfriend says Oscar checked with her when he heard noises at night

"Blade Runner" Oscar Pistorius slept with a firearm by his side and often suspected there was an intruder in his home at night, his ex-girlfriend Samantha Taylor on Friday told the court where he is on trial for murder.

However, on those occasions he always woke her up to ask whether she had heard a suspicious noise too, Taylor said under questioning from State prosecutor Gerrie Nel.

Nel begged Judge Thokozile Masipa's indulgence to introduce fresh evidence before asking Taylor to describe these incidents, taking the disabled athlete's defence lawyer by surprise.

It raises questions as to what transpired between Reeva Steenkamp and Pistorius on the night he shot and killed her through a locked toilet door, according to him because he believed there was an intruder was hiding behind it.

Taylor, who began dating Pistorius in 2011 when she was still a teenager, described Pistorius as a volatile man who frequently shouted at her, her best friend and her sister.

"There was a lot of commotion in our relationship," she said, adding that it ended for good when he attended an award ceremony with Steenkamp.

"He cheated on me with Reeva Steenkamp."

Taylor was repeatedly asked by Nel whether Pistorius, 27, sounded like a man or a woman when he shouted. She firmly responded: "It sounded like a man, My Lady."

The question relates to one of the pillars of Pistorius's defence - that he screams in a high-pitched voice that can readily be mistaken for a woman's.

His lawyer Barry Roux, SC, has used this argument to undermine the testimony of State witnesses who claim they heard a woman's terrified cries coming from his house before Steenkamp died.

Roux claims it was in fact his client who they heard scream on the night Steenkamp died as she was too severely injured to make a sound.

Roux said the defence had re-enacted screaming in tests at Pistorius's home and would submit the results to the court to challenge the testimony.

"On the 21st of February there were indeed tests done and part of the tests was a woman screaming, loud, as loud as she could," Roux said.

When Roux's turn came on Friday to cross-examine Taylor, he immediately brought her to tears.

He said she was lying about the end of her relationship with Pistorius and that he would provide copies of their emails to prove this.

Judge Masipa briefly adjourned the court, before Roux resumed questioning and set out to prove that Taylor's recollection of events during her relationship with Pistorius was unreliable.

This included her account of the night he pulled out his gun to scare off somebody he believed had followed them to his home.

Roux has systematically questioned the credibility of every State witness since the trial began on Monday. - Sapa