Forensic tests carried out by expert Roger Dixon for Oscar Pistorius’ murder trial have been rigorously challenged by state prosecutor Gerrie Nel in South Africa.

Roger Dixon’s sequence for the shots that killed Reeva Steenkamp contradicts that of a police ballistics witness and pathologist.

Oscar Pistorius, 27, denies intentionally killing Reeva Steenkamp in the early hours of Valentine’s Day last year.

He says he fired in fear at a toilet door, mistaking her for an intruder.

The prosecution says the 29-year-old model and law graduate was deliberately killed after the couple had an argument.

Oscar Pistorius faces 25 years to life in prison if convicted of premeditated murder.

The trial has now adjourned for a break and will reconvene on Monday May 5.

Before the questioning got under way on Thursday, Judge Thokozile Masipa warned those watching the televised proceedings in an overflow court next door about their “unruly” behavior.

Judge Thokozile Masipa said she had been made aware that there had been shouting and cheering at times.

Roger Dixon’s sequence for the shots that killed Reeva Steenkamp contradicts that of a police ballistics witness and pathologist

“It is not an entertainment place,” she said.

The prosecutor Gerrie Nel then continued his cross examination of Roger Dixon, a defense witness, who says he believes Reeva Steenkamp was standing at an angle to the door and that all four bullets hit her as she fell to the ground.

Earlier in the trial, ballistics expert Captain Christiaan Mangena said he believed Reeva Steenkamp was standing up facing the closed door when she was hit in the right hip.

He said she then fell back on to a magazine rack next to the toilet before three more bullets were fired at the door, one of which missed her.

Roger Dixon’s testimony challenges the state’s version that Reeva Steenkamp would have had time to scream after the first bullet and that Oscar Pistorius then changed aim and continued firing.

The forensic expert also told the court about light tests carried out in Oscar Pistorius’ bedroom and sound tests of a cricket bat striking a door and bullets hitting a door.

However, Gerrie Nel has sought to cast doubt on Roger Dixon’s credibility and qualifications as a forensics witness, suggesting some of the tests were amateurish.

He criticized him for not using a model the same height as Oscar Pistorius when on his stumps in a photograph to illustrate what neighbors would have been able to see through the bathroom window at night.

In the photograph a man was kneeling in front of the window.

“It is something I omitted. I overlooked it at the time,” said Roger Dixon, a geologist and university lecturer who worked as head of materials analysis at a police forensic laboratory in Pretoria for 18 years until 2012.

Gerrie Nel also sought to prove that he was out of his depth when he was testifying about marks on Reeva Steenkamp’s body.

He had identified one as a bruise which other pathologists had not, Gerrie Nel said.

At one stage on Wednesday Roger Dixon used the phrase “in my layman’s understanding”.

“Now you call yourself a layman. You see how irresponsible it is to make inferences that aren’t in your area of expertise,” the prosecutor replied.

Before the court adjourned, he was re-examined by defense lawyer Barry Roux and described how an official at the shooting range, where the sound tests were carried out, mistook the sound of the cricket bat striking the door for gunshots.

Roger Dixon took the stand on Tuesday after seven days of testimony from Oscar Pistorius came to an end with him reading a Valentine’s Day card from Reeva Steenkamp.

If Oscar Pistorius is acquitted of murder, the court must consider an alternative charge of culpable homicide, for which he could receive about 15 years in prison.

He also faces charges of illegally firing a gun in public and of illegally possessing ammunition, both of which he denies.

There are no juries at trials in South Africa, and his fate will be decided by the judge, assisted by two assessors.

Oscar Pistorius is known as the “Blade Runner” because of the carbon-fibre prosthetics he uses on the track.

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