Paralympic star Oscar Pistorius's chances of winning bail appeared to increase dramatically today after an embarrassing series of blunders and confusion in the prosecution case.

Just hours after the police officer leading the murder hunt told the athlete's bail hearing in Pretoria that the performance enhancing drug testosterone and steroids had been found at his mansion home shortly after the killing of girlfriend Reeva Steenkamp, prosecutors changed their story.

In a humiliating U-turn, a spokesman for South Africa's National Prosecution Agency said there had been an error in the evidence of detective Warrant Officer Hilton Botha when he identified the substance found in the 26 year-old's bedroom.

There had been gasps in court when WO Botha, a policeman for 24 years and the first officer to arrive at the Pistorius house on Valentine's Day following the shooting of the 29 year-old model and law graduate, and prosecutors claimed testosterone had been found together with needles.

Discovery of the sports drug could potentially have brought questions over the star's achievements at London 2012 where he became the first athlete to compete at an Olympics and Paralympics, winning two gold medals and a silver.

At one stage, the detective supposedly providing the key facts to keep Pistorius in custody had agreed with the defence lawyer that police had no evidence challenging the runner's claim he accidently killed his girlfriend in a bathroom, believing it was an intruder.