Transcript for Oscar Pistorius Murder Trial: Neighbor Heard 'Terrible Screams'
Today was the first day of a very big trial. The legendary athlete accused of murdering his girlfriend. Oscar Pistorius arrived in the courtroom in South Africa today. And his girlfriend's family was there, ready to stare him down. ABC's hamish Macdonald, tonight, on the dramatic encounter. Reporter: With the eyes of the world upon him, Oscar pisotorius arrives at court. Open up, open up. Reporter: He is escorted directly in front of the family of the woman he killed. Reeva steenkamp's mother says she wants to look him in the eye and see the truth for herself. But he looks straight ahead, and there is no eye contact. Known as blade runner, Oscar Pistorius is still widely admired in his home country, having overcome enormous odds to compete on the world stage. He now faces four charges, including murder. How do you plead? Not guilty, my lady. Reporter: Reeva steenkamp was a model, a reality television star and a trained lawyer, too. The defense claims the killing was a tragic mistake. Pistorius thought steenkamp was an intruder in the home. But in court today, a neighbor described hearing blood-curdling screams from a woman, then a series of gun shots in the early hours of Valentine's day last year. So how can you be sure you heard this? I am absolutely certain I heard a woman screaming. Reporter: Prosecutors now hope to portray him as gun-happy and reckless. This is just the first step in a long and drawn-out trial. There are many more to go. Proceedings will last at least three weeks. Pistorius faces a possible life sentence. Hamish Macdonald, ABC news, Pretoria, South Africa.
This transcript has been automatically generated and may not be 100% accurate.