The trial of Oscar Pistorius begins in Pretoria, South Africa with the Olympic and Paralympic track star pleading not guilty to murdering his girlfriend, Reeva Steenkamp. (Reuters)

The murder trial of Olympic hero Oscar Pistorius begins Monday as a judge opens proceedings billed as “the trial of the century” in Pretoria, South Africa.

At issue is whether Pistorius, known as “Blade Runner” for the carbon-fiber prosthethics he runs on, deliberately or accidentally shot to death his girlfriend, model Reeva Steenkamp, during the night on Valentine’s Day 2013. It’s a case that is drawing comparisons to the O.J. Simpson double-murder trial in the U.S. in 1995 and it certainly will rival that for media attention worldwide, if not quite in the U.S. The trial will be televised, although testimony by Pistorius or witnesses who do not consent will not, and it will be riveting.

Pistorius faces one charge of premeditated murder and a firearms charge in addition to gun charges from previous incidents. A conviction on the murder charge in South Africa would carry a mandatory life sentence. The evidence, at least on the eve of the trial, seems less nuanced than the Simpson case, but, as with the U.S. trial that resulted in the acquittal of Simpson, the police investigation will be called into question by defense lawyers.

This much seems certain: Steenkamp was in the toilet closet in the bathroom of Pistorius’s home in the middle of the night and died after Pistorius shot her through the door. He does not claim self-defense. “I cannot bear to think of the suffering I have caused her and her family, knowing how much she was loved,” he stated in an affidavit last year. “I also know that the events of that tragic night were as I have described them.”

From there, the debate begins. Pistorius said in the affadavit that he and Steenkamp “were deeply in love” and had a quiet dinner at his home. Prosecutors say a witness near the house heard them arguing in the middle of the night. Pistorius claims that, after the couple went to bed, he was awakened by a noise and grabbed his gun because he sleeps without his prosthetic legs and “had to protect Reeva and myself.” He says he entered the bathroom on his stumps and his lawyers will argue that the angle of the shots will bear that out. He claims he put on the prosthetics after the shooting, found her body and carried her downstairs, where she died.

Cellphones are likely to provide some key evidence along with the toilet door because Steenkamp had taken her phone into the toilet. Did she place a call or text someone? Will GPS show movements throughout the house? Last year, the magistrate questioned the thoroughness of the investigation because police did not trace calls from numerous phones at Pistorius’s home and it appears that authorities have taken steps to obtain more information. Last week, they went to Apple headquarters in California for help in accessing information on a phone or phones.

As with the Simpson case, there are questions about the investigation. Hilton Botha, the lead investigator, was far from compelling on the stand at hearings last year. He admitted that investigators had run out of protective shoe covers and contaminated the crime scene by walking through the house without them. He also initially testified that testosterone and needles were found, but then said he may have misread the label.

A female judge, not a jury, will decide Pistorius’s fate. If convicted of premeditated murder, Pistorius would face a mandatory life sentence. If not convicted, he would still face a lesser charge of “culpable homicide” based on negligence.