PRETORIA, South Africa — The case against Oscar Pistorius faltered Wednesday as a series of police errors came to light and the lead investigator acknowledged that authorities have no evidence to disprove the Olympian, who has both legs amputated, claiming he accidentally killed his girlfriend.

Detective Hilton Botha’s often confused statements left prosecutors shaking their heads. He had misjudged distances and claimed that testosterone had been found at the crime scene – in some cases prohibited for professional athletes. However, the prosecution later contradicted this statement.

The second day of the hearing, which was supposed to be only a bail hearing, was almost like a full-blown trial against the 26-year-old runner, with his lawyer Barry Roux grilling Botha’s testimony step by step under cross-examination.

Botha acknowledged that police left a 9mm bullet from the barrage of fire that killed Reeva Steenkamp in a toilet and lost illegal ammunition they found in the house. And the investigator himself walked through the crime scene without protective shoe covers, potentially contaminating the area.

The authorities, Roux said, would selectively “use every piece of evidence to filter out the possibly most negative connotation and present it to the court.”

The case has kept South Africa on tenterhooks. Journalists and curious onlookers crowded into the brick-walled courtroom where Pistorius, nicknamed the “Blade Runner” because of his prosthetic legs, is being charged with premeditated murder on Valentine’s Day.

Pistorius said he thought Steenkamp was an intruder and shot her out of fear. Prosecutors say he planned the murder and attacked her as she crouched behind a locked bathroom door.

The day seemed to start well for the prosecution: Botha presented new details of the shooting that seemed to call into question Pistorius’ account of the moments before the 29-year-old model’s death.

Ballistic evidence, he said, showed the bullets that killed them had been fired from a high altitude, backing up the prosecution’s claim that Pistorius was wearing prosthetic legs when he aimed at the bathroom door. The sportsman has claimed he was standing only on his stumps and felt vulnerable and frightened when he opened fire from a low position.

Prosecutor Gerrie Nel projected a plan of the bedroom and bathroom and said it showed that Pistorius had to walk past his bed to get to the bathroom and that he could not have done so without seeing that Steenkamp was not sleeping there.

“There is no other way to get there,” Nel said, contradicting Pistorius’ claim that he had no idea Steenkamp was no longer in bed when he fired four bullets into the bathroom door, hitting her with three.

Botha supported the prosecutor’s testimony, saying the holster for Pistorius’ 9mm pistol was found under the left side of the bed where Steenkamp was sleeping and it would have been impossible for Pistorius to get to the gun without checking to see if it was there.

“I think he knew Reeva was in the bathroom and he fired four shots through the door,” the detective said.

Botha described bullets hitting Steenkamp’s head and shattering her right arm and hip, causing Pistorius, who was holding his head in his hands, to sob.

When asked if Steenkamp’s body showed “any pattern of defensive wounds” or bruising from an attack, Botha said no. When asked if investigators had found anything that was inconsistent with Pistorius’ version of events, he also replied “no.” However, he later said that nothing had contradicted the police version either.

The testimony began with the prosecutor telling the court that a neighbor heard “incessant” shouting in Pistorius’ upscale home in a gated community in the capital Pretoria between 2 and 3 a.m. before the shooting.

However, Botha later said under cross-examination that the witness was in a house 550 metres away, possibly out of earshot. When the prosecutor questioned him again, he halved his estimate, as confusion prevailed much of his testimony.

At one point, Botha testified in court that police had found syringes and two boxes of testosterone in Pistorius’ bedroom – a statement that prosecutors later retracted on the grounds that it was too early to identify the substance because it was still being tested.

“It is not certain (what it is) until the forensic investigations are completed,” Medupe Simasiku, a spokesman for the South African Directorate of Public Prosecutions, told the Associated Press. It is currently unclear whether it is a “legal or illegal drug.”

The defense also denied the claim. “It’s an herbal remedy,” Roux said. “It’s not a … banned substance.”

Still, Botha provided potentially incriminating details from Pistorius’ past, saying the athlete was once involved in an accidental shooting at a Johannesburg restaurant and asked someone else to “take the blame.”

The messenger also threatened men on two separate occasions, Botha said, allegedly telling one of them that he would “break his legs.”

The investigator said police found two iPhones in Pistorius’ bathroom and two BlackBerrys in his bedroom, and neither had been used to call for help. Security guards at the condominium called the athlete, Botha said, and all he said was, “I’m fine,” while crying uncontrollably.

Roux later suspected that Pistorius had used a fifth phone, which the police had not picked up, to call for help.

The question now is whether Botha’s problematic testimony will be enough to convince Chief Justice Desmond Nair to keep Pistorius in jail until trial. While Pistorius must comply with the strictest bail conditions under South African law, the judge has said he would consider relaxing them based on the testimony at the hearing. Closing arguments were scheduled for Thursday.

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Gerald Imray reported from Johannesburg. Associated Press writer Michelle Faul in Johannesburg contributed to this report.