Pistorius sits in the dock waiting to be called to testify during his ongoing murder trial at the high court in Pretoria. Judge Masipa later postponed the trial until April 7.

AFP/Pretoria

The judge overseeing Oscar Pistorius’s murder trial has adjourned the case for more than a week – just before the star Paralympian was expected to take the stand for the first time – because a senior court official was sick.

“One of my assessors is not well,” said Judge Thokozile Masipa. “I suggest that we postpone this matter to the 7th of April.”

Pistorius was expected to be called as a witness for the defence and later to face fierce cross-examination about how and why he killed his girlfriend Reeva Steenkamp on Valentine’s Day a year ago.

The “Blade Runner” sprinter denies a charge of murder, saying that he mistook the model for an intruder.

Judge Masipa had been appointed two court assessors to help her manage the high profile case, which has also seen South Africa’s justice system put in the dock amid allegations of police bungling.

The case was originally scheduled to run for three weeks until last Friday, but is now slated to run until at least mid-May.

Pistorius is the only surviving witness to the events inside his house in the early hours of February 14, 2013, so his testimony is likely to be key.

The 27-year-old has to explain why he fired four shots at the model and aspiring television actress through a locked toilet door, and undermine prosecutors’ argument that her death was premeditated murder.

It will be the first time he speaks in public since the Valentine’s Day killing, besides pleading “not guilty, milady”, and the occasional “yes, milady” to Masipa during his trial.

Defence lawyer Barry Roux has read two almost identical affidavits on behalf of his client – one at his bail hearing last year, another at the start of the trial on March 3.

Pistorius does not have to testify, but his defence team has indicated it believes it will be in his interest to explain the night’s events.

If the accused does take the stand, law dictates he has to be the defence’s first witness.

“I think it’s going to be a very tough time for Pistorius. Every person who testifies in court goes through pressure, especially the accused,” said William Booth, a Cape Town-based criminal lawyer not involved with the case. “Every word could count against you.”

Pistorius’s lawyers would want him to face prosecutor Gerrie Nel’s cross-examination for as little time as possible, but he could spend as much as two days on the stand.

On Tuesday the state called the last of its 21 witnesses against the athletics star.

The court heard testimony that depicted Pistorius as hot-headed and gun-obsessed, as well as hearing from police ballistics and cellphone experts and a forensic pathologist.

“If you don’t testify the court will say, well, they haven’t any version of yours tested under cross-examination,” said Booth. “His evidence only has to be reasonably possibly true, and he doesn’t have to prove anything.

“If there was somebody who witnessed that, he wouldn’t need to testify. But he’s the only witness.”

Neighbours say that they heard screams from a man and woman and gunshots the night of the killing, while a police ballistics expert said Steenkamp was hit in the hip first before suffering gunshot wounds to her arm, hand and head.

This means she almost certainly cried out in pain – alerting her boyfriend she was in the bathroom – before the lethal shot, prosecutors contend.

They have also asked questions about food in the 29-year-old model’s stomach that suggests she was awake two hours before her death – contradicting Pistorius’s version that they had been asleep.

The defence says that the shots followed too close on one another to leave her any time to scream, and that the shrieks were actually from Pistorius, who sounds like a woman when he is anxious.

The double amputee, who was born without calf bones and garnered worldwide fame by running on two carbon fibre blades, earning the “Blade Runner” monicker, says he shot Steenkamp because he mistook her for an intruder.

Defence lawyers say the pair were deeply in love, and that most of their cellphone correspondence was affectionate, despite one message in which Steenkamp said she was sometimes afraid of Pistorius.

If found guilty of premeditated murder he faces life in prison.

But even under his version of events the Paralympian could be convicted of the lesser charge of manslaughter, which can also mean a heavy prison sentence.

According to South African law, you can only fire a gun at someone if there is direct danger.

“If he’d shot one shot it might have been different,” said Booth. “Four shots into a small room through a door – that’s a problem.

“Even if that version is accepted by the judge, she could still say ‘You exceeded what you were entitled to do by the law’.”