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 on Friday. “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 face fierce cross-examination about how and why he killed his girlfriend Reeva Steenkamp on Valentine’s Day a year ago.

The “Blade Runner” denies a charge of murder, saying 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 Judge Thokozile 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.