A ballistics expert testifying for Oscar Pistorius's defence said the bullets that hit Reeva Steenkamp were not in the order prosecutors claimed.
Wollie Wolmarans sought to show that the sequence of the bullets showed Ms Steenkamp was reaching for the toilet door, and not putting her hands to her face defensively.
The model's final movements have been used by the defence to show Mr Pistorius shot the 29-year-old mistaking her for an intruder, while the prosecution has sought to show he knew she was in the cubicle and wilfully fired.
Mr Wolmarans told the court that Ms Steenkamp was close to the toilet door and leaning slightly forward when the first of four gunshots hit her hip.
The next bullets hit her arm and hand, and the final bullet hit her head as she was falling backward.
Mr Wolmarans's testimony runs in the face of police ballistics testimony.
Police said one bullet missed and ricocheted off the wall, injuring Ms Steenkamp's back and that the final bullet hit her hand and head, as she was sitting in a defensive position with her hands over her head.
The defence witness said all four hollow-point bullets hit the model and law graduate, saying the same bullet could not have hit both her hand and head, otherwise there would be brain tissue found on her hand.
"I would not expect that tissue to go on the wall, it would be on the inside of the hand," said Wolmarans.
He said the back wounds were "consistent with falling off a blunt surface" and caused when Ms Steenkamp fell on a wooden magazine rack in the toilet.
The state's version, that Ms Steenkamp fell into a seated position on the magazine rack, "doesn't make sense to me," he said.
The expert testimony bolsters the defence claim Ms Steenkamp was reaching for the toilet door handle when she was shot by Mr Pistorius.
The Paralympic gold medallist claims he shot his girlfriend by accident, believing her to be an intruder in his upmarket Pretoria home.
In contrast, the state claims the 27-year-old athlete shot Ms Steenkamp in a fit of rage following an argument.
If found guilty of premeditated murder, the double-amputee faces up to 25 years to life in prison.
Mr Pistorius began the day in good spirits, cracking a rare smile in court as he greeted Mr Wolmarans, an ex-policeman with over 30 years' experience in ballistics.
Yet as Mr Wolmarans testified on graphic details about Ms Steenkamp's death, Mr Pistorius bent his head in the dock, shielding his eyes with his hand from photos of the bloody crime scene shown on the court television monitors.