While most of the attention during the Oscar Pistorius murder trial has been on the fallen sprinter himself or on Reeva Steenkamp, the model girlfriend he has admitted shooting, another player in the case has received considerably less attention: Judge Thokozile Masipa.

It is Masipa who will decide whether Pistorius will spend the next 25 years in prison for murder. And it is Masipa whom Pistorius has to try to convince that he's innocent.

For more than 40 years, all trials in South Africa have been heard by judge alone. That law was enacted in 1969 during the apartheid era, when it was often too difficult to find willing jurors not tainted by racism to sit through trials.

Masipa is only the second black woman ever appointed to the bench in South Africa and she has a reputation for tough rulings. The former social worker and crime reporter came to law late in life, graduating law school in her mid-40s. But just seven years later, she was appointed a judge of the High Court of South Africa.

Since then, she has made a number of headline-grabbing decisions, says TSN legal analyst Eric Macramalla.

"She comes down very hard in cases of violence against women, namely because outside of every war zone, South Africa has the highest rate of female deaths by gunshots," Macramalla told CTV News Channel Monday.

"She is aware of this and she's experienced and she's seasoned."

In one case, Masipa sentenced a man named Shepherd Moyo to a 252-year sentence for raping three women during home robberies in Johannesburg. She told Moyo that what bothered her most was his lack of remorse and the effects his crimes had on the women.

"The worst in my view is that he attacked and raped the victims in the sanctity of their own homes where they thought they were safe," she said at the time.

In another case, Masipa handed a life sentence to a policeman, Freddy Mashamba, who shot and killed his former wife after an argument about their divorce.

"No one is above the law," Masipa told him. "You deserve to go to jail for life because you are not a protector. You are a killer."

Macramalla says it's clear from Pistorius' testimony on Monday that he is trying to earn Masipa's sympathy. He apologized several times to Steenkamp's family and said he thought of their pain every day. He also told the court he had tried to live a good life, but had deeply emotionally affected by a number of brushes with crime and by break-ins at his house.

Though the court is not broadcasting images of Pistorius as he testifies, it's clear from the audio that he has been emotional throughout his testimony, weeping several times.

Masipa has not shown any reaction to the sprinter's words and Macramalla says it's not clear what she may be thinking.

"Whether she'll be swayed by emotion remains to be seen, but one would expect that that's going to be difficult," he said.