Chief prosecutor Gerrie Nel questions forensic geologist Roger Dixon (not seen) during cross-examination at the murder trial of paralympian Oscar Pistorius on Thursday, 17 April 2014. The athlete's murder trial resumed in the North Gauteng High Court in Pretoria on Thursday – the last day before a two-week postponement. Picture: Alet Pretorius/Media24/Pool

Pretoria - The methodology of a key defence witness has been put to the test throughout the day at Oscar Pistorius's murder trial.

Roger Dixon returned to the witness stand in the High Court in Pretoria on Thursday for the remainder of his cross-examination, after Gerrie Nel on Wednesday questioned his credentials and integrity.

Dixon, a forensic geologist, was brought to the stand to testify on several forensic aspects of the case, including the bathroom door Pistorius shot through the night he killed Reeva Steenkamp.

Roger was then asked about the analysis he'd conducted on Pistorius's prosthetic legs.

He had determined that varnish on the legs and sock fibres on the door had indicated Pistorius had tried to kick down the door.

Dixon said he had not brought his evidence about the legs to court on Thursday.

Nel said a piece of the prosthetic legs had been cut out for analysis, but Dixon had failed to keep track of its chain of custody.

Dixon argued that he had a written record of where it had been on his computer.

Nel asked if there was significance of the fibres on the mark on the door pointing downwards. Dixon said since the door had been cleaned, these fibres could have moved and this wasn't significant.

Nel asked if there had been any transfer of the varnish of the door to the sock.

Dixon said there could be tiny fragments on the sock, but he hadn't tested it.

The prosecutor brought the prosthetic leg before the court, and said that to the naked eye, no varnish was visible on the sock.

Nel said the portion of the prosthetic leg that had been removed was smaller than the mark on the door.

But Dixon said that the remainder of the wear and tear suffered by the leg was still visible on its sole.

The expert said he'd closely examined the prosthetics to come to his conclusion, but had not tested its effects on other similar doors.

Dixon was then asked about thee cricket bat, which Pistorius used to break down the cubicle door.

He said he had taken into account the angle of the bat when it hit the door, but wasn't sure about the exact angle used - only using approximations.

Nel requested for access to Dixon's computer for the photos the witness took of the estate and its lighting conditions.

A photo already handed in showed Dixon's test when he and his team shot through a similar door.

This image showed the path of the bullet after the shots had been fired. Nel asked if they'd measured the angle that the door had been fired at. Dixon said that the recreation was made to be like that of when Pistorius had shot through the door.

He said some of the angles, height and distance had been measured and clearly marked.

Dixon was then questioned on the “witness boards” the team had created, which showed the secondary projectiles that would have resulted from firing through the door.

Dixon said the photographs of these boards were made available on request by the State, but Nel asked how the expert knew this.

He said he'd inferred this, but said he hadn't realised he'd have to hand these over to the State personally.

Dixon said he'd handed over a memory stick with the photos to the defence counsel.

Nel asked if Dixon had measured the angles of the projectiles on the witness boards. Dixon said the boards provide an approximation of the behaviour of the projectiles, so he did not measure them.

Defence advocate Barry Roux then began his re-examination of Dixon.

Earlier, Dixon had brought an image of a person standing on their knees to show the court what the Stipp's could have seen on the night of the shooting.

Johan Stipp claimed he saw a man moving across the bathroom window.

The image showed that he most likely would have only seen the head of the person.

But on Thursday morning, Dixon explained the model in his photo was 20 centimetres shorter than Pistorius.

Roux argued that based on Stipp’s view of the top half of the window, the neighbour still wouldn't have been able to see Pistorius cross the window.

Dixon was excused from the stand and Roux asked that the case be postponed an hour early so as to not prejudice the next witness.

Judge Thokozile Masipa ruled that when the court returned on May 5, the missing hours would be recovered.

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The Star