Oscar Pistorius's girlfriend Reeva Steenkamp was standing when the Paralympian shot her, the High Court in Pretoria has heard.

The 27-year-old is accused of murdering the South African model by firing gunshots through a bathroom door in his home on Valentine's Day last year.

Police ballistics expert Capt Christiaan Mangena returned to the witness stand on day 13 of the murder trial to give an account of how Steenkamp was shot in the early hours of February 14.

Mr Mangena told the court that Steenkamp was standing in the toilet cubicle facing the bathroom door when the first shot struck her right hip.

The expert went on to claim that the model fell back onto a magazine holder and tried to protect herself by crossing her arms over her head, before the second bullet bruised her back after ricocheting off the wall.

The court heard that the third and fourth bullets hit Steenkamp's right arm and head respectively, which caused the model to collapse with her head on the toilet seat.

Pistorius denies murder by claiming that he mistook Steenkamp for a burglar when he fired the gunshots.

The trial has been adjourned until Monday.