Suzette Naude, her soft-spoken court registrar, says the judge doesn't even confide in her.
The judge arrives in a Mercedes at Pretoria's High Court each morning. By 6.30am, she is at her desk, poring over the day's documents, more than two hours before any other judge.
Friends describe her as religious, health-conscious and hard-working. "Once you come in here and become a permanent judge, you begin to see that you spend most of your life here, instead of home," Masipa once said.
Usually based in the Johannesburg High Court, which has the highest case burden in the country, she jokes that even her four grandchildren need to make appointments to see her. Her husband, a tax consultant, does the cooking.
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Susan Abro, a senior attorney who served with Masipa on the electoral court for six years, says the judge is "very clever, very professional", but, above all, warm and modest.
"She comes from a human rights background, so that's the point - you must allow people to feel like they've had their day in court, to feel as if they've been heard," she said. "She's not one of the ones who makes a big splash about themselves, makes judgments so they'll be reported. And she has a wry sense of humour."
Born on October 16, 1947, Masipa was the first of 10 children, and one of only three surviving.
She grew up on a two-bedroom house in Orlando East, then a poor part of Soweto. Now, her childhood home is a creche for poor children, set up by her late mother. She helps pay the bills and also finances a nearby project that her sister runs for unemployed women.
Moving between schools in Soweto, the Alexandra township outside Johannesburg and Swaziland, she worked hard. "From a very young age, I wasn't a great socialiser; I would be buried in my books," she said in 2008. She became a social worker, inspired by her mother, who was a teacher.
Wanting to go to university, but lacking the money, Masipa worked as a clerk, then a messenger, then a tea girl, watching young white girls with high school diplomas doing the jobs she wanted. Eventually, she found her way to university, graduating with a BA in social work in 1974. The list of "funny" jobs continued, until she applied for a junior reporter's position at the World newspaper, where she worked as a crime reporter.
As the women's section editor at the Post, to which she moved, Masipa wrote about schools, education, the quality of textbooks, the conditions of labour for domestic workers. The promotion was a big step up. "No mean feat," fellow journalist Pearl Luthuli recalled. "That position was for a white woman".
At 29, she marched with other female journalists to protest at the detention of several of their black male editors at the Post and demand press freedoms. She was arrested and thrown into a filthy jail cell with four of her colleagues;.
Judge Thokozile Matilda Masipa.
It took Masipa 10 years to complete her law degree at the University of South Africa, while working as a fulltime journalist, wife and mother. She graduated in 1990.
The announcement of her appointment as the second black woman in South African history to the bench in 1998 was accompanied by a note of her hobbies: dancing, gardening, yoga.
"In a sense, she is a pioneer," said Albie Sachs, a former constitutional court justice. Masipa jokes that she is probably the "youngest" ever appointed to the high court, after only seven years at the bar.
But black female judges are still a rarity. Even though the population is 80 per cent black, only 44 per cent of superior court judges are. And out of the country's 239 judges, only 76 are women.
She has admitted that her township background and disadvantaged childhood have an impact on her judgments, allowing her to identify with the people in the dock before her, especially young criminals, who she feels should be given an opportunity for rehabilitation.
The Department of Justice has been at pains to say Masipa's assignment to Pistorius' murder trial was a procedural one, but many South Africans also regard it as a significant and welcome statement about the changing nature of the country's justice system.
"It is a tough place to be, because for a long time it was only men who sat here," Masipa once said.
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"And in our culture it's even tougher, because some men are just not used to seeing women giving orders. But one gets used to it. It's not you as a woman who's there - it's the position that you fill. So you just get on with it."
The Masipa files
Born: Thokozile Matilda Masipa, born October 16, 1947, in Soweto, Johannesburg. Studied social work, then law. Among other jobs, she worked for many years as a journalist. Married with two children.
Best of times: In 1998, she became only the second woman in South African history to be called to the bench. The Pistorius case will be scrutinised the world over.
Worst of times: She spent years during the apartheid era frustrated by her inability to prosper, and then spent years studying law part-time. Arrested when working as a journalist for protesting against the detention of colleagues and the lack of freedom.
She says: "From a very young age, I wasn't a great socialiser, I would be buried in my books. I am compassionate by nature, but coming from this area [Soweto], I think, does make me a lot more compassionate."
They say: "She comes from a human rights background, so that's the point - you must allow people to feel like they've had their day in court." - Susan Abro, a senior lawyer.
-Observer
