Forensic expert challenges Pistorius' version of events

Oscar Pistorius was "probably not wearing his prosthetic legs" when he fatally shot his girlfriend through a toilet door, a forensic expert told his murder trial.

The matter of whether Pistorius was wearing his prosthetic legs is critical to the case, as it tests the Olympic and Paralympic star's assertions about exactly what happened on the night he killed girlfriend Reeva Steenkamp in his bathroom on Valentine's Day last year.

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

ITV News Africa Correspondent Rohit Kachroo reports:

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

Prosecutors want to prove that Steenkamp's shooting was a premeditated killing, but Pistorius denies this.

Vermeulen told the court, "The marks on the door are actually consistent with him not having his legs on and I suspect they must be similar to the height that he was when he fired the shots."

Lead defence lawyer Barry Roux countered by suggesting that even with his legs on, Pistorius would not be swinging a bat at the same height as an able-bodied person.

Close-up photographs of the damaged door were shown in court, as well as scuffs on the bat autographed by South African test cricketer Herschelle Gibbs.

Roux later heaped scorn on the state's evidence, again accusing police of shoddy detective work, after Vermeulen testified that police reassembled the broken door with a temporary adhesive.