Prosecution pillories Pistorius expert

State prosecutor Gerrie Nel sought to prove that forensic geologist Roger Dixon was out of his depth in testifying about the lighting, sound and physical evidence inside Pistorius's home.

Dixon, a university professor, told the court about the sound made by Pistorius's cricket bat hitting his toilet door, visibility in the star sprinter's bedroom and blood splatter.

Pistorius's defence team has argued that neighbours who testified to hearing "bloodcurdling screams" followed by gunshots were mistaken.

If proven correct, the neighbours' account could punch a hole through Pistorius's claim he did not know Steenkamp was in the toilet.

Pistorius's defence team has tried to show that the noises were in fact Pistorius bashing a cricket bat against his toilet door after realising he mistakenly killed the model.

"Are you a sound expert, sir?" asked Nel. "Have you received training in decibels and sound?"

Not specifically, said Dixon.

He also testified that Pistorius's bedroom was so dark the athlete could not have seen whether Steenkamp was in bed.

When Nel asked the geologist about how he analysed the visibility in Pistorius's bedroom room at night, Dixon said: "My lady, the instruments I used there were my eyes."

"Are you a blood splatter expert?" said Nel. "I have received no training in blood splatter analysis," said Dixon, a former employee of the South African Police Service.

Pistorius's lawyer Barry Roux is expected to call up to 17 witnesses to bolster the athlete's story that he shot his girlfriend Reeva Steenkamp by mistake, believing she was an intruder breaking into his upmarket home in a gated Pretoria community.

The Paralympic gold medallist has pleaded not guilty to intentionally killing the 29-year-old model and law graduate.

He has also pleaded not guilty to three other charges connected with the reckless discharge of a firearm and the illegal possession of ammunition.

He stepped down from the witness stand on Tuesday, after a gruelling cross-examination at the hands of Nel.

Legal experts said Pistorius, who was evasive and argumentative on the stand, did himself more harm than good.

"I think it's a desperate man," said William Booth, a criminal lawyer based in Cape Town. "The more questions you ask somebody like Oscar, it could actually get worse."

A lot of reading

Earlier, the judge overseeing Pistorius's trial granted an adjournment from Thursday afternoon until May 5, citing scheduling concerns raised on behalf of the state.

The prosecution, with the backing of the defence, had asked for a delay because an assistant prosecutor is involved on another case and other members of the legal team had planned holidays.

"A private matter always poses a challenge, especially when it is a long-term matter," said Judge Thokozile Masipa.

"For that reason it will take precedence," said the judge. "As well as the fact that counsel have made themselves available way beyond the time that was initially estimated."

Judge Masipa said she and her assessors will use the time to study the hefty record, which runs over 2,000 pages excluding the bail application.

"Much of the evidence is technical evidence from expert witnesses, there is a lot of reading to be done and my assessors and I will use the break to read the record," she said.

Taking into account Easter holidays, the adjournment is for seven working days, a period the judge said was "not unduly long" and could "hardly cause the accused prejudice."

The Pistorius murder trial has run far over the originally allotted time of three weeks.