Pistorius trial: Police conduct faces scrutiny

Pretoria, South Africa: Police Col. J.G. Vermeulen testified about the bullet-marked door, a critical piece of evidence in the case against the double-amputee Olympian, who fired through the door on February 14, 2013, killing girlfriend Reeva Steenkamp.

Defense lawyer Barry Roux raised questions about possible contamination of evidence related to police handling of the door. Roux also suggested Vermeulen did not consider Pistorius's version of events, despite the colonel's assertion that he acted objectively in his investigation.

Roux indicated that police investigators might have also left a shoe print on the door, the door itself might have been kept in a policeman's office and not in proper evidence storage, and missing fragments from the door weren't examined.

Earlier, Vermeulen knelt in court and swung a cricket bat at Pistorius's toilet door, demonstrating how the double-amputee athlete may have bashed the door to get to the girlfriend he had just fatally shot.

Vermeulen said he believed Pistorius was on his stumps when he swung his bat at the cubicle door.

The defense insisted instead that Pistorius was wearing his prosthetic legs when hitting the door in the pre-dawn hours of Valentine's Day last year - and the marks from the bat on the door were lower down because the athlete swung with a bent back.

The intricate argument over whether Pistorius, the first amputee to run at the Olympics and now on trial for murder, was on his prosthetic limbs or not is important because it could match parts of his story that he accidentally shot Steenkamp. Or it could also suggest that he is lying.

The 27-year-old athlete has said he fearfully approached the bathroom on his stumps and shot Steenkamp by mistake, thinking she was an intruder hiding behind the door. According to his account, he then put on his prostheses and tried to kick down the locked toilet door, and battered it with a cricket bat to get to his girlfriend after realising what he had done.

Prosecutors maintain he intentionally shot the 29-year-old model and have charged him with murder. He pleaded not guilty to all charges against him, which also include three firearm related counts.