The three 'key' factors that will be decisive in Pistorius' murder trial

The South African media has raised three key questions that may be important to the murder trial of Paralympian Oscar Pistorius, who is accused of shooting and killing his model girlfriend Reeva Steenkamp on Valentine's Day last year.

As his lawyers launched an aggressive defence on day one of the trial, tearing into a witness who claimed to have heard 'bloodcurdling screams' as Steenkamp was killed, a report has raised three questions, which could key to the trial.

According to News24, the first question is did the couple argue on the night of the shooting as in his affidavit, Pistorius claimed the couple spent a quiet night at home, although the prosecution is expected to challenge that account on basis of the testimony of neighbours who claim to have heard shouts coming from the couple's house.

The couple's mobile phone records could also offer evidence of a fight given that Steenkamp reportedly had her phone with her in the toilet when she was shot.

The second key question was whether the police irreparably tainted the crime scene as in the bail hearing, former lead detective Hilton Botha admitted he had entered Pistorius's home and investigated the scene without the correct protective footwear, lost track of ammunition at the scene and made several false assumptions.

The third and the most important question that comes up is why did not Pistorius call the police after the incident, and the report mentioned that in his affidavit, Pistorius claimed to have called two numbers after realising he shot Steenkamp, and none of them was the police.