A reconstruction of a toilet cubicle in the High Court in Pretoria. Picture: Antoine de Ras

Pretoria - A forensic expert has been brought onto the stand at the Oscar Pistorius murder trial to try and invalidate key aspects in the testimony of witnesses who claim they heard the athlete shooting and killing Reeva Steenkamp.

Roger Dixon, forensic geologist, was the next defence witness called to the stand in the High Court n Pretoria.

With more than 30 years of experience, Dixon was an expert formerly in the employ of the SAPS forensics unit.

Dixon was the former boss of one of the State's forensic experts, Colonel Johan Vermeulen.

Dixon was brought onto the case to analyse the lighting conditions in Pistorius's home, specifically the main bedroom and en suite bathroom.

The expert said on March 25, he closed all the curtains and turned off all the lights in the bedroom, and on a moonless night one couldn't see a hand in front of one's face.

He said the night of the shooting, the moon had set early.

With the CD player lights on, the expert said he could only just see down the passage leading towards the bathroom.

Dixon said the light in the bathroom wasn't working, and the bulb in the toilet itself wasn't functioning.

On the night of the March 25, Dixon went towards the home of Pistorius's neighbours, the Stipp's, who lived nearby and testified for the State.

From the street outside their home, Dixon took a photograph of the Stipp's balcony where they had stood when they heard the shooting at Pistorius' home.

A second photo was shown to the court of almost total blackness, which showed how Pistorius's bathroom window would have appeared to the Stipps.

Dixon said that with the lights off in Pistorius's bathroom, it would have been impossible for the Stipps to have seen anything.

Defence advocate Barry Roux suggested it wouldn't have been possible for the Stipps to have seen a man walking past the window as they had claimed.

Another photo showed that if a man was on his knees - or stumps, as Pistorius claims - it would have been difficult to see more than just the person's head at the window.

Dixon was then asked about the sequence of damages to the toilet cubicle door, which had been reconstructed in court.

He had examined the door in November last year.

Dixon said the damage on the door was to the right hand side, and this was caused by the cricket bat Pistorius had used to break down the door after the shooting.

Dixon said there were most likely only three blows with the bat.

Damage on the frame of the door showed the points where Pistorius had struck it.

Roux asked if Dixon had tested the sound made by a cricket bat on the door. Dixon said he had conducted tests on a door of the same material, both with a firearm and cricket bat.

He said he had struck the door himself, and had recorded its sound levels at 60 metres and 180 metres. This was the distance from Pistorius's house his neighbours would have been on the night of the shooting.

Roux played an audio sample of the door being hit in rapid succession, as Pistorius claimed he had hit the door.

Dixon said he had been standing in a batting position to hit the door so quickly.

The expert also said the cracks in the door leading from the bullet hole proved the shots were fired before Pistorius had tried to hit the door with the bat.

A stain on the door showed when the panel broke, a piece of it landed in the blood on the floor, also proving the sequence.

An image of a white patch and white fibers on the door showed Pistorius had tried to kick down the door with his sock-covered prosthetic legs.

Dixon said the socks material was consistent with the fibers.

Earlier, Pistorius short re-examination began with Roux asking the athlete how he defined an “accident”.

Pistorius said the shooting of Reeva Steenkamp was unintentional as he feared for his life. When he saw thought the toilet cubicle door hid a perceived attacker, he felt vulnerable for himself and Steenkamp.

He felt complete terror and helplessness.

Pistorius said he didn't consciously pull the trigger, but he reacted.

Roux then showed the court a picture of the jeans that had formed a key part of the State's case earlier today. The pants were in a different position to how they had been presented earlier, yet another attempt to show that Pistorius believed police investigators had moved items on the scene during their probe.

Roux asked about Pistorius's relationship with Steenkamp, and presented a Valentine's Day letter from the young model to the athlete.

“I think today is a good day to tell you that I love you,” read the card.

Roux then closed his re-examination.

One of the assessor's also asked Pistorius if Steenkamp had access to the alarm codes and remote. Pistorius said she had access to the remote but he wasn't sure if she knew how to turn off the alarm.

The State has argued that forensic experts had determined that Steenkamp had eaten approximately two hours prior to the shooting.

Pistorius said on Monday that if she had gone to eat something, she would have set off the internal house alarms.

On being questioned, Pistorius also said that the bathroom light wasn't working at the time of the shooting.

Pistorius left the dock slowly as he packed away his lengthy notes before returning to the dock.

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The Star