The trial of Oscar Pistorius has heard how the athlete's neighbour was woken by screams the night his girlfriend Reeva Steenkamp died.

Michell Burger says she also heard four shots on the morning of Valentine's Day last year, near the athlete's home in Pretoria.

His lawyer earlier said any allegation Oscar Pistorious wanted to shoot or kill his girlfriend 'cannot be further from the truth'.

The court has been hearing Michell Burger's evidence through a translator.

Meanwhile Oscar Pistorius' lawyer told the court the crime scene was tampered with.

The hearing began with the murder charge being put to Mr Pistorius. When asked by judge Thokozile Masipa how he pleaded he said: "Not guilty, my lady." He also pleaded not guilty to a series of firearms charges.

He also pleaded not guilty to a series of firearms charges.

Reporter Shane Germaner of The Star newspaper in South Africa spoke to the Pat Kenny Show here on Newstalk.

For much of the defence's opening statement Pistorius had his eyes closed and occasionally sighed. The court heard how Pistorius thought an intruder was in his bathroom when he shot Ms. Steenkamp.

His lawyer also said Pistorius denied an allegation the pair had argued before the shooting.

Questions over the investigation into the shooting were also raised, as the team alleged the crime scene had been "contaminated and tampered with". State prosecutor Gerrie Nel denied there had been any tampering.

Pistorius' lawyer Barry Roux outlined the central planks of his defence in court this morning.

Families divided

The Pistorius family are in court in Pretoria, sitting just yards away from Miss Steenkamp's relatives. 

Reeva's family have said they want to look Pistorius in the eye and judge for themselves whethar he is guilty.

In a landmark ruling, large parts of the case will be broadcast live by three remote-controlled cameras in court, but testimony given by Pistorius cannot be shown.

The South African judge who made the decision said he had weighed up arguments for a fair trial from the Pistorius camp with principles of open justice and freedom of expression.

The trial, which will hear from more than 100 witnesses, is scheduled to run for three weeks but could go on for longer.

Trial by judge

The South African legal system does not have trials by a jury, so a judge will preside over proceedings and ultimately pronounce Pistorius innocent or guilty.

The double amputee (27) faces charges of murder, illegal possession of ammunition and two additional counts relating to shooting a gun in public in two separate incidents before shooting Ms Steenkamp at his home in Pretoria.

He stands accused of fatally shooting the model (29) and reality TV star four times through a toilet door intentionally, following a jealous row and then lying extensively about it.

Prosecutor Gerrie Nel called Pistorius a man "willing and ready to fire and kill" as the state charged him with premeditated murder.

If found guilty of premeditated murder, the Paralympic and Olympic athlete could be jailed for at least 25 years.

Judge Thokozile Masipa has open to her the lesser offence of negligent killing.