The murder trial of Oscar Pistorius begins today as South Africa prepares for what is expected to be a marathon legal battle that throws a spotlight not just on the world-famous double-amputee athlete, but on his homeland's criminal justice system and gun culture.

The trial, which has been compared to that of the OJ Simpson case in the United States 20 years ago, has led to the establishement in South Africa of a unique cable television channel dedicated to it.

The 24-hour channel, called The Oscar Pistorius Trial – A Carte Blanche Channel, launched on Sunday night with footage of the sportsman's girlfriend, Reeva Steenkamp, who was shot dead by him in the early hours of the morning on February 14 last year at his home. While the Olymian denies murder and says that he mistook Steenkamp for an intruder, the prosecution maintains that he intentionally shot her several times after an argument.

State prosecutors are expected to paint an unflattering portrait of Pistorius as reckless, hot-headed and obsessed with guns, and have lined up 107 witnesses for the trial, including Pistorius's ex-girlfriends Melissa Rom and Samantha Taylor, whose mother welcomed the end of their relationship. Erin Stear, who has denied reports she had an affair with Pistorius, will also take the stand, as will the former footballer Mark Batchelor, who has claimed that Pistorius threatened to "break my legs" because he was a close friend of Steenkamp, a law graduate, model and reality TV star.

Police have said they found unlicensed .38-calibre ammunition in Pistorius's house, while his Twitter account revealed he had boasted of going into "full attack recon mode in the pantry" after thinking an intruder was in his home.

The court will hear how, in one incident, Pistorius accidentally discharged a pistol under the table in a Johannesburg restaurant. He also put a bullet through the sunroof of a girlfriend's car in a fit of rage.

Pistorius will also come face to face with Steenkamp's mother, June, who made her feelings clear in a TV interview last year, recalling an incident in which Steenkamp phoned her from Pistorius's car. "She was afraid," June said. "She was so afraid. She said, 'Mummy, I'm in the car with Oscar and he's driving like a lunatic. Like a lunatic.' So I said, 'Will you just give him the phone?' She gave the phone to Oscar straight away. And I said, 'If you hurt my baby, I will have you wiped out.'"

Mobile phone records could be key during the trial, potentially indicating evidence of a fight. Steenkamp is said to have had her phone with her in the toilet when she was shot. Police have been trying to gain access to Pistorius's iPhone, which might contain evidence of a fight in the form of text messages.

Another key piece of evidence, according to experts, may be the blood-spatter analysis of the inside of the toilet cubicle, which could give an indication of Steenkamp's position when she was shot, including whether she was sitting on the toilet, or hiding behind the door, as prosecutors suspect.

Pistorius faces charges of murder, illegal possession of ammunition, and two additional counts relating to shooting a gun in public in two separate incidents before last year's Valentine's Day killing.

Criminal law experts believe that if the prosecution fails to prove premeditated murder, firing several shots through a closed door could bring a conviction for the lesser charge of culpable homicide, a South African equivalent of manslaughter covering unintentional deaths through negligence. Sentences in such cases range from fines to prison. They are left to courts to determine and are not set by fixed guidelines.