POLICE photographs of the blood-spattered scene where Oscar Pistorius shot his girlfriend indicate that evidence was moved, in violation of investigation procedure, the athlete's chief defence lawyer has said.

The High Court in Pretoria, where Pistorius is on trial for murder, heard that Warrant Officer Bennie van Staden took hundreds of images. These include blood marks, bullet casings, a gun and a cricket bat found in Pistorius's bathroom after the double-amputee athlete killed Reeva Steenkamp on February 14 last year.

Chief defence lawyer Barry Roux has challenged previous police witnesses, seeking to uncover contradictions and reported mishaps to support his argument that officers bungled the investigation.

He asked Mr van Staden to explain differences in images of the 9mm pistol Pistorius used to shoot Ms Steenkamp through a closed toilet door, and of a cricket bat the Paralympian used to hit the door.

"It seems there was movement of the bat" in the interval between two photos taken by Mr van Staden, Mr Roux said.

"It seems like that," Mr van Staden conceded.

The police photographer also acknowledged two pictures of the gun indicated a mat underneath it could have been shifted.

Mr Roux said one photograph also differed from the other because it showed a wooden splinter on the gun handle, and he questioned Mr van Staden's statement that he remembered being alone while he was taking photographs.

"Are you sure that you were alone up there?" Mr Roux asked, citing timelines from the photographs of another officer as evidence that they were in the same area at the same time.

Mr van Staden said he was sure that he was alone.

The officer earlier said he took nine photographs of Pistorius soon after the shooting, with the athlete seen in some of the images standing in blood-stained prosthetic legs and wearing blood-soaked shorts in the garage of his home.

Pistorius, 27, is charged with premeditated murder for killing Ms Steenkamp, 29. The trial continues.