A Conviction In Oscar Pistorius Trial Could Rest On One Detail: Which Shot Killed Reena Steenkamp?

A South African police ballistics expert testified in the Oscar Pistorius murder trial Wednesday, claiming that the sprinter shot Reeva Steenkamp in her hip, before firing a bullet which struck her fatally in the head. The question of when Steenkamp was killed, in the midst of the four shots Pistorius fired, is central to the case. This is because the defense has argued differently from the ballistics expert: They claim that Steenkamp was struck in the head by Pistorius' first shot, and thus could not have been the source of any subsequent screaming.

The expert, Christian Mangena, said he believes Steenkamp was standing behind the door when Pistorius fired the first bullet into his bathroom, striking her in the hip and knocking her down onto a magazine rack near the seat of the toilet. She then likely stayed seated defensively, trying to protect herself — "Reeva must have had both hands covering her head protectively," he said — before another bullet struck her in the head, killing her.

Mangena's testimony is effective for the purposes of the prosecution, corroborating witnesses who described hearing a woman screaming both before and during the gunfire. Pistorius' neighbor Michelle Burger testified to this, and also described hearing the screams start to fade after the last shot.

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Since killing Steenkamp in February of 2013, Pistorius has said that he became confused and mistook her for a home invader. By his own account, and corroborated by some testimony, the high-profile athlete felt vulnerable and paranoid about his security, and was frequently armed.

Unfortunately, that same testimony alleges a pattern of massively reckless behavior involving firearms, including two incidents of Pistorius firing a shot in public.

Mangena also concluded, through reconstruction of the crime scene, that Pistorius had not been wearing his prosthetic legs when he killed Steenkamp. This could be viewed as beneficial to his claim of having acted fearing for his safety, not to commit a premeditated murder.

If convicted of Steenkamp's murder, the 27-year-old Pistorius will face a minimum of 25 years to a possible life imprisonment.