PRETORIA, South Africa: Oscar Pistorius was probably on his stumps when he fatally shot his girlfriend through a toilet door, a forensic analyst said Wednesday at the double-amputee athlete's murder trial.

Wielding the cricket bat in his hands, Police Col. Johannes Vermuelen knelt down before swinging it at the wooden door in a court reconstruction to show the angle of the marks and to suggest they could only have been made by someone much shorter than him.

The 27-year-old double amputee is charged with the murder of model and law graduate Reeva Steenkamp, whom he shot through the locked toilet door on Valentine's Day last year. The matter of whether Pistorius was on his stumps is critical because it tests his assertions about what exactly happened on the night he killed Reeva Steenkamp in his bathroom on Feb. 14, 2013.

The athlete has said he fearfully approached the bathroom on his stumps and shot Steenkamp by mistake, thinking she was an intruder. 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 realizing what he had done.

Testimony Wednesday focused on the angle from which Pistorius hit the toilet door with a cricket bat, which could determine whether he was on his stumps, or was wearing his prostheses.

Police Col. J.G. Vermeulen, a forensic analyst, said he believed Pistorius was on his stumps when he fired through the toilet door, based on the angle of the bullet marks in the door, which was on display in the courtroom.

However, Vermeulen said the bat was used to hit the door from a low position, and he knelt and swung Pistorius' cricket bat at the door to demonstrate his point.

“It's quite low down on the door,” Vermeulen testified about one of the marks he said were made by the bat. He said it was “not the normal position that I would expect from a mark from a cricket bat.” He said marks on the door were consistent with Pistorius “being in a natural position without his prostheses.” Defense lawyer Barry Roux countered that Pistorius hit the door with a “bent back” and that the low marks were consistent with such a body position.

Vermeulen also said a steel plate in the main bathroom in Pistorius' home had been damaged by being hit with a “hard” object, or after the object fell against it.