Wollie Wolmarans sought to show that the sequence of the bullets showed 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 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.
Wolmarans told the court that Steenkamp was close to the toilet door and leaning slightly forward when the first of four gunshots hit her hip.
Wolmarans's testimony runs in the face of police ballistics testimony, which said one bullet missed and ricocheted off the wall, injuring 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.
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The state's version, that Steenkamp fell into a seated position on the magazine rack, "doesn't make sense to me," said Wolmarans.
The expert testimony bolsters the defence claim Steenkamp was reaching for the toilet door handle when she was shot by Pistorius.
The Paralympic gold medallist claims he shot his girlfriend by accident, believing her to be an intruder in his upmarket Pretoria home.