There was no evidence to suggest that the firearm used to kill Bianca Warburton would go off accidentally, the High Court in Johannesburg heard on Friday.
“It would take a deliberate action ...to fire this,” forensic analyst Albert Wessels said in testimony.
The force or pressure on the trigger needed to be 27 neutrons or 2.8 kilograms to fire the pistol.
Wessels was testifying in the trial against the three men accused of murdering the psychology student last year.
The accused, Stembiso Mseleku, 24, Mphumuzeni Gumede, 27 and Moffat Mthonti, 29, pleaded not guilty to murder and robbery.
Gumede and Mthonthi however pleaded guilty to possessing a firearm.
Last year in the Wynberg Magistrate's Court, Mseleku said he was guilty of murder and that “it was a mistake.”
On Thursday, he however pleaded not guilty.
Witness Mpho Mbedegi said he saw Mseleku running away from the scene with a gun.
All accused were in police custody. - Sapa