PRETORIA, South Africa – The prosecution case against Oscar Pistorius began to unravel Wednesday with revelations of a series of police blunders and the lead investigator’s admission that authorities have no evidence challenging the double-amputee Olympian’s claim he killed his girlfriend accidentally.

Detective Hilton Botha’s often confused testimony left prosecutors rubbing their heads in frustration as he misjudged distances and said testosterone – banned for professional athletes in some cases – was found at the scene, only to be later contradicted by the prosecutor’s office.

The second day of what was supposed to be a mere bail hearing almost resembled a full-blown trial for the 26-year-old runner, with his lawyer, Barry Roux, tearing into Botha’s testimony during cross-examination.

Police, Botha acknowledged, left a 9 mm slug from the barrage that killed Reeva Steenkamp inside a toilet and lost track of illegal ammunition found inside the house. And the detective himself walked through the crime scene without wearing protective shoe covers, which potentially could have contaminated the area.

Authorities, Roux asserted, were selectively taking “every piece of evidence to try to extract the most possibly negative connotation and present it to the court.”

Pistorius says he mistook Steenkamp for an intruder and shot her out of fear, while prosecutors say he planned the killing and attacked her as she cowered behind a locked bathroom door.

Projecting a diagram of the bedroom and bathroom, prosecutor Gerrie Nel said it showed Pistorius had to walk past his bed to get to the bathroom and could not have done so without seeing that Steenkamp was not asleep there.

“There’s no other way of getting there,” Nel said in disputing Pistorius’ claim that he had no idea Steenkamp was no longer in bed when he pumped four bullets into the bathroom door, striking her with three.

Botha described how bullets struck Steenkamp in the head and shattered her right arm and hip, eliciting sobs from Pistorius, who held his head in his hands.

However, when asked whether Steenkamp’s body showed “any pattern of defensive wounds” or bruising from an assault, Botha said “no.” He again responded “no” when asked if investigators found anything inconsistent with Pistorius’ version of events, though he later said nothing contradicted the police version either.