Oscar Pistorius injured a professional boxer by firing a gun in a restaurant then asked his friend to take the blame, a court has heard.

Cruiserweight fighter Kevin Lerena, giving evidence at his friend's murder trial, said he and several others were dining with the Paralympic star in Johannesburg on January 13th last year.

Mr. Lerena said he saw Pistorius' friend Darren Fresco pass a gun to him under the table, shortly before a shot went off.

He said "There was blood on my toe. I went to the bathroom. I was shocked. Oscar apologised. I remember that I was in shock".

"He told Fresco: 'Tell them it was you, I don't want any more media hype around me.'" Mr. Lerena is the first witness to agree to appearing on camera while giving his evidence.

He told the court that when Mr. Fresco handed the gun to Pistorius he said it was "one up", a term meaning there is one bullet in the chamber.

He said Pistorius removed a bullet from the chamber, then the "next moment" there was a shot.

Earlier, evidence given by one of the prosecution's key witnesses was repeatedly challenged by Pistorius' defence team during a tense cross-examination.

Charl Peter Johnson's claim that he heard a woman screaming after the final gunshot on the night Reeva Steenkamp was killed was criticised by Barry Roux, because it did not appear in his initial witness statement.

Mr. Roux said "In your evidence you described the woman screaming. You said you could hear the fear. What is significant is that in your wife's (Michelle Burger) testimony, she said she could hear the woman's intense fear in her screams. Yet this is not in your statement".

"When you gave evidence yesterday, it was not stated in your statement but you now speak about the scream after the last shot. I think you don't know what you are saying. You are saying all the evidence that your wife gave us yesterday".

But Mr Johnson said: "I don't think it is strange that we used the same words."

The issue of the sound of a woman screaming is a key point for the prosecution. The claims by neighbours that they heard the screams suggest Pistorius would have known it was Ms Steenkamp, rather than an intruder, as he fired.

At one point, as Mr. Roux became increasingly exasperated during his questioning, he turned around and glanced at Pistorius and told Mr. Johnson "A man's life is at stake here."

Pistorius showed no emotion as he - surrounded by his cousins - entered the court in South Africa's administrative capital earlier. There were shouts and whistles as he made his way through the crowd towards the court's entrance, where he is on trial accused of murder.

Mr. Johnson started his evidence by saying his phone number was read out in court on Tuesday, and he had received phone calls from a member of the public as a result.

He said "The message was intimidating. I feel that my privacy has been compromised".

He will return to court on Thursday to continue giving evidence. In the meantime the defence will pore over notes he made about the night of the killing.

Pistorius faces four charges: premeditated murder, the illegal possession of ammunition and two further counts related to shooting a gun in public in two separate incidents before the killing.

Pistorius, known as Blade Runner, denies all of the charges, including the allegation he deliberately killed his girlfriend after a jealous row. He maintains he shot Ms. Steenkamp after mistaking her for an intruder.

The trial is scheduled to last for three weeks and will hear from more than 100 witnesses. If he is found guilty Pistorius could be jailed for at least 25 years.

His fate will be decided by Judge Thokozile Masipa because South Africa does not have a jury system.

Shain Germaner is a journalist with The Star in South Africa. He told the Pat Kenny Show here on Newstalk the State is hoping to paint a picture of Pistorius.

Issue of sound travelling

The issue of sound - how far it can travel and whether noises late at night can be easily misinterpreted - is fast becoming a key factor in the Oscar Pistorius murder trial.

His defence team has already indicated it intends to call expert witnesses who will testify there is little chance the athlete's neighbours, who claim to have woken to the sound of screaming, shouting and gunshots, heard anything accurately at all.

Reeva Steenkamp was in a small toilet with the window closed when she was shot dead through the locked door by Pistorius, who claims to have mistaken her for an intruder in the early hours of Valentine's Day 2013.

The nearest neighbours - Michelle Burger and Charl Peter Johnson - say they heard a woman's screams that night shortly before, during and shortly after four gunshots.

It was damaging evidence for the defence, casting serious doubt on Pistorius' assertion he thought Ms Steenkamp was in bed when he opened fire.

The clear inference from the evidence is if she was screaming loud enough to wake the neighbours before the gunshots, then the athlete must have known where she was.

But defence advocate Barry Roux has been fierce in his cross-examination, repeatedly stating the couple were 177 metres away, that they must have heard Oscar's screams not Reeva's.

And, crucially for their case, he argued the sounds that neighbours believed were gunshots could not have been the result of bullets being fired at all.

The defence says Pistorius bashed his way through to the bathroom door with a cricket bat after realising he had shot her by mistake. The bangs of the bat, Mr. Roux insisted, not the shots of a gun, were what they heard.

Pistorius' legal team have had a year to put together his case and they will have spent time collating the evidence that might poke holes in the neighbours' compelling and emotional accounts.

There will have been audio tests - re-enactments to show the sounds and distances involved - which will likely show how sound travels and distorts. The prosecution has opened its case by creating a vivid picture - through sounds overheard - of a murder not an accident.

There was an argument, Ms. Steenkamp screaming and terrified, and then gunshots. The defence know they have to convince the judge that what was heard that night could still fit with Oscar Pistorius' version of events.