Oscar Pistorius
"Blade Runner" Oscar Pistorius stands in the dock during a break in court proceedings at the Pretoria Magistrates court. Reuters

A South African judge is due to give his ruling on the bail plea of Oscar Pistorius who has been charged with premeditated murder of his girlfriend Reeva Steenkamp, 29, on Valentine's Day.

Prosecutors are opposing bail saying Pistorius is "prone to violence", while his lawyers claim that he is too famous to jump bail.

Lead defence lawyer Barry Roux told the magistrate, Desmond Nair: "I think there will be a level of shock if he is not released."

The bail hearing is taking place against the background of a replacement of the chief investigator in the case, Hilton Botha, who himself is facing attempted murder charges. Lt Gen Vineshkumar Moonoo, a senior detective, has been put in charge of the probe.

Pistorius's defence is banking on what they see as contradictory statements made by Botha during his deposition.

Roux has been quoted as saying: "The poor quality of the evidence offered by investigative officer Botha exposed the disastrous shortcomings of the state's case."

The defence is seeking a downgrading of the premeditated murder charge. They say the defendant was actually trying to save Steenkamp.

They have also cited forensic evidence and the post mortem report, which indicate that the victim's bladder was empty. This, they say, shows that she was not trying to flee from Pistorius and had gone to the bathroom in the middle of the night as is normal - contrary to the prosecution argument.

The prosecutors are arguing that Pistorius has a "history of violence" and that despite the defence plea that the ace sprinter fired his gun in self-defence, he had committed murder.

"What we can't forget is the applicant is charged with murdering a defenceless, innocent woman," prosecutor Gerrie Nel is quoted as having told the court.