* Pistorius pleads not guilty to murder charge
* Neighbour: woman "screamed terribly" before shots
* Victim's mother in court as trial opens
* Massive attention from international, local media
* Trial likely to run for weeks (Releads with witness, adds quotes, details)
By David Dolan
PRETORIA, March 3 (Reuters) - The first witness at Oscar Pistorius' murder trial told the court on Monday she heard "bloodcurdling screams" from a woman followed by shots, a dramatic opening to a case that could see one of global sports' most admired role models jailed for life.
Taking the stand after the Olympic and Paralympic star pleaded not guilty to murdering his girlfriend, model Reeva Steenkamp, on Valentine's Day last year, Michelle Burger, who lives in an estate nearby, testified she was woken up in the middle of the night by a woman shouting for help.
"I was still sitting in the bed and I heard her screams," Burger told the Pretoria High Court, speaking in Afrikaans through an interpreter.
"She screamed terribly and she yelled for help. Then I also heard a man screaming for help. Three times he yelled for help," she said.
Thinking it was a violent break-in - a possibility in crime-ridden South Africa - Burger said her husband called the private security firm guarding their upmarket housing estate in Pretoria's eastern suburbs, before the pair heard more shouts.
"I heard the screams again. It was worse. It was more intense," Burger told the court, her voice cracking with emotion. "She was very scared."
"Just after her screams, I heard four shots. Four gun-shots," she said. "Bang ... bang, bang, bang."
"It was very traumatic for me. You could hear that it was bloodcurdling screams." Throughout her testimony, the 27-year-old Pistorius sat impassively, staring at the floor.
The athlete, who was born without legs but reached the 2012 Olympic 400 metres semi-final running on carbon-fibre "blades", argues that Steenkamp's killing was a tragic accident after he mistook her for an intruder hiding in the toilet.
The testimony from Burger, who lived 177 metres from Pistorius' home in a neighbouring housing estate, was not televised live at her request, although the audio was still broadcast.
"NOT GUILTY" PLEA
Earlier, a sombre Pistorius dressed in dark suit, white shirt and black tie stood before judge Thokozile Masipa to plead not guilty to murdering Steenkamp, a law graudate, women's rights campaigner and familiar face on South Africa's celebrity party scene.
He also pleaded not guilty to several other firearms charges, including one of discharging a pistol under the table of a swanky Johannesburg restaurant and another of putting a bullet through the sun-roof of a former girlfriend's car.
As Pistorius entered the packed courtroom, Steenkamp's mother June followed him with her gaze.
In his opening address, Pistorius' lawyer, Kenny Oldwage, sought to portray the state's allegations as an unwarranted character assassination of a young man deeply in love.
Prosecutors are seeking to prove that Pistorius fired four rounds from a 9 mm pistol through the door of the toilet in a deliberate attempt to kill whoever was behind it.
Steenkamp was hit three times, in the head, arm and hip. She was declared dead at the scene.
If the state succeeds in convincing Masipa of intent to kill, Pistorius could get life, in all likelihood a minimum of 25 years behind bars.
At his bail hearing last year, Pistorius admitted to culpable homicide, equivalent to manslaughter, a crime that could see him put away for 15 years - or he could leave the Pretoria High Court a free man, with no more than a slap on the wrist and a suspended sentence.
Coming less than a month after the rape, disembowelling and murder of a teenager near Cape Town, the 2013 shooting of Steenkamp caused outrage and drew further attention to the high levels of violence against women in South Africa.
The trial before Masipa - juries were abolished by the apartheid government in the 1960s - is set to last a minimum of three weeks but with as many as 107 witnesses waiting to be called by either side it is almost certain to last far longer.
The proceedings have attracted massive media attention, with hundreds of foreign and domestic media camped outside the Pretoria court, a reflection of Pistorius' status as a global symbol of triumph over physical adversity.
The trial is also being broadcast live on television, a first for South Africa, where, two decades after the end of arpartheid, the justice system is often accused of favouring the rich and wealthy, who are able to afford the best lawyers and forensic experts. (Reporting by David Dolan; Writing by Ed Cropley; Editing by Pascal Fletcher)
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