Pretoria, South Africa (CNN) -- The murder trial of Oscar Pistorius opened Monday with chilling testimony from the South African amputee track star's neighbor, who described "bloodcurdling screams" coming from next door, followed by gunshots, the night of Reeva Steenkamp's death last year.
"Something terrible was happening at that house," Michelle Burger testified.
She told the court that she heard a woman's screams and a man screaming for help.
"Just after 3, I woke up from a woman's terrible screams," she said. "Then I also heard a man screaming for help. Three times he yelled for help."
Burger said her husband called authorities. She later told her husband that she feared the woman had witnessed her husband being shot "because after he screamed, we didn't hear him."
Language issues caused problems after the lunch break, as defense attorney Barry Roux pressed Burger on her account during cross-examination.
She frequently had to help her Afrikaans interpreter translate her words into English, and eventually dropped speaking in her native tongue altogether.
Roux questioned Burger's timeline of events and what she heard, asking if the "bang" sounds she heard might not have been gunshots, but rather a cricket bat bashing at the bathroom door.
She answered that she had clearly heard gunshots, testily answering Roux's questions about timing, saying she "didn't sit there with a stopwatch and take down the timing of each shot."
A short time before her testimony, Pistorius pleaded not guilty to murdering Steenkamp, his girlfriend, inside his house a year ago. He also pleaded not guilty to several weapons-related charges.
It's expected to take about three weeks for a judge to hear both sides and decide whether Pistorius mistook Steenkamp for a burglar, as he says, or killed her in cold blood.
Parts of Pistorius' trial are being televised live -- a first in South Africa -- after a judge's decision last week allowing cameras in the courtroom. But any testimony by Pistorius, or witnesses who do not consent, will not be televised.
June Steenkamp is inside the courtroom, marking the first time she has faced her daughter's killer in court. Reeva's parents have avoided previous court appearances because, they said, they wanted privacy. Pistorius' brother and sister were also present for Monday's proceedings, which were delayed by an hour and a half because of pretrial "hiccups," Judge Thokozile Matilda Masipa said.
With the aid of two assessors who will help her evaluate the facts of the case, Masipa -- only the second black woman appointed to the bench since the end of apartheid -- will determine Pistorius' fate. South Africa abolished jury trials in 1969.
A few minutes before the trial's scheduled start at 10 a.m. (3 a.m. ET), Pistorius arrived at the Pretoria High Court through a back door, avoiding a massive media circus assembled in front.
Pistorius faces one charge of premeditated murder and a firearms charge associated with Steenkamp's killing, as well as two separate gun indictments from previous incidents. In South Africa, premeditated murder carries a mandatory life sentence, with a minimum of 25 years. He also could get five years for each gun indictment and 15 years for the firearms charge.
If he isn't convicted of premeditated murder, the sprinter would face a lesser charge of "culpable homicide," a crime based on negligence, and could be looking at up to 15 years on that charge, experts say.
Pistorius, 27, and Steenkamp, 29, were a young, attractive and high-profile couple who were popular in South Africa's social circles. The "Blade Runner" won six Paralympic gold medals and became the first double amputee runner to compete in the 2012 Summer Olympics in London. Cover girl Steenkamp, who was soon to star in a TV reality show, was on the cusp of becoming a celebrity in her own right.
Everything changed before dawn on Valentine's Day 2013, as Steenkamp lay lifeless in a pool of blood on the floor of her boyfriend's house in an upscale gated community in Pretoria. Moments before, Pistorius says, he had pointed his 9 mm pistol toward an upstairs toilet room and fired four bullets through the locked door.
The sprinter's lawyers will argue that he was a man deeply in love with his girlfriend who made a terrible mistake. Pistorius says he heard a noise from the bathroom in the middle of the night and, feeling vulnerable without his prosthetic legs on, charged toward the bathroom on his stumps and shot through the toilet door in order to protect himself and Steenkamp.
"I felt a sense of terror rushing over me," he said in his court affidavit. "There are no burglar bars across the bathroom window and I knew that contractors who worked at my house had left the ladders outside."
"It filled me with horror and fear of an intruder or intruders being inside the toilet. I thought he or they must have entered through the unprotected window. As I did not have my prosthetic legs on and felt extremely vulnerable, I knew I had to protect Reeva and myself."
Prosecutors are painting a different picture. They say that the pair had an argument and that Steenkamp locked herself in the toilet. At last year's bail hearing, the state said Pistorius put on his prosthetic legs, collected his gun from under the bed and walked down the hall leading from the bedroom to the bathroom before unloading a flurry of shots through the door.
Prosecutors say the sprinter's act was a premeditated murder -- that he took the time to put on his legs before walking to the bathroom and shot through the toilet door, intentionally killing his girlfriend.
Pistorius is not claiming self-defense; he is claiming to have been mistaken about his need for self-defense. He is denying that he intentionally, unlawfully killed Steenkamp. He has never denied killing her.
The case has put the spotlight on South Africa's rampant gun violence and high crime rates. Roughly 45 people are murdered every day, according to police statistics, and the number of home burglaries is up 70% in the last decade. In 2012, more than half of South Africans told the country's police force that they were afraid of having their homes broken into. In his affidavit, Pistorius said he had been the victim of violence and burglaries before, including death threats.
The trial has also divided opinion in South Africa. Many of his fans find it difficult to believe a national hero could be capable of the crime he's been charged with. Others find his version of events that night implausible, and point to troubling details that the case has dredged up about Pistorius' past.
In its indictment, police described Pistorius recklessly shooting a 9 mm handgun out of the sunroof of a car on a public road in 2010. Police have also charged him with unlawfully firing a Glock 27 pistol at a restaurant in January 2012. A friend of the sprinter told CNN that Pistorius was showing the gun to a friend when it went off at the outdoor cafe accidentally.
Since Steenkamp's death, Pistorius -- who was freed on bail -- has shied away from the spotlight. He lives at his uncle Arnold Pistorius' house in Pretoria, and although video surfaced last year of him training, he has not returned to the track in an official capacity. But support from his family has been unwavering.
"We have no doubt there is no substance to the allegation and that the state's own case, including its own forensic evidence, strongly refutes any possibility of a premeditated murder or indeed any murder at all," Arnold Pistorius said.
In the meantime, Steenkamp's family has tried to focus on the memory of Reeva -- not on the media and legal circus unfolding in Pretoria. Her parents are seeking "closure, and to know that our daughter did not suffer on that tragic Valentine's Day," June and Barry Steenkamp said in a prepared statement in mid-February.
"It's not about the court case," her uncle, Mike Steenkamp, told CNN. "It's about Reeva, and Reeva can never be part of it."
At the same time, Mike Steenkamp said seeing Pistorius at the trial may bring at least some closure to what has been a harrowing year for the family.
"I would like to be face to face with him and forgive him, forgive him for what he's done. That way I can then probably find more peace."