Testifying before the commission's amnesty committee in Pretoria, former enigineering student Cornelius van Wyk said the throats of the three victims had been cut after they were shot dead.
He said he and Jurgen White were on the premises to steal firearms for their ultra-rightwing organisation, the Nationalist Socialist Partisans.
Van Wyk is serving a life sentence for the three murders, and has applied for amnesty. White and another member of the organisation, Johannes Grobbelaar, died after a clash with the police near Upington in November 1991.
Van Wyk was convicted in September 1994 of the murders of Makoarela Dobani, Wilson Dobani and Maria Roux at Cloud's End, Louis Trichardt in October 1991.
The rightwing organisation had only four members and was set up in July 1991 to counter what they saw as "an inevitable bloodbath when the communists take over".
"We were absolutely convinced that all whites would be killed," van Wyk said.
The organisation's aim was to acquire arms for military resistance. It saw itself as becoming the co-ordinator of all rightwing bodies for this purpose.
After an earlier attempt to steal firearms at a Louis Trichardt military base had been abandoned, White suggested that they rob a private home at Cloud's End. He had known the daugther of the family, and said only a domestic worker would be at home.
"We were planning to tie her up if she saw us," van Wyk said.
He and White arrived at the house in the early hours of October 14, 1991. A car left the premises at about 6am. White, who knew the movements of the residents, told him the house would be empty, van Wyk said.
They moved closer and took up position in shrubs near the house. Makoarela Dobani was wiping the verandah. When she realised something was amiss, and White greeted her in har own language.
"She turned around and he shot her in the back," van Wyk said. "He then stepped forward and cut her throat.
"At that point Wilson Dobani came around the corner and saw his wife lying on the ground. White shot at him but missed. He shouted at me to shoot, after which I chased and shot him.
"As Mr Dobani hit the ground, White rushed past me and cut his throat," van Wyk said.
They then entered the house and were rifling through cupboards in search if firearms.
"At some stage I heard him slamming the door of a cupboard closed before shooting through it," said van Wyk. "I instinctively also fired off a shot through the door.
"Only later on I saw Mrs Roux had been in the cupboard. White opened the door and cut her throat."
Van Wyk said he was horrified at this act.
"We have been fighting for whites and Afrikaners, and now we have murdered one of our own people."
The death of the two black people did not really sadden him, van Wyk said. "But to see Mrs Roux die was horrible."
Van Wyk, 26, testified that he had passed matric with distinction and studied engineering at Pretoria University with a bursary. He quit his studies after six months, partly because he wanted to devote more time to his political activities.
Since his arrest, he had obtained a BA degree, and was studying an honours degree in psychology in prison.
Jean du Plessis, who was the leader of the National Socialist Partisans, has also applied for amnesty.
He was in September 1994 jailed for 12 years for crimes including robbery, the theft of weapons for the SA National Defence Force, and the illegal possession of firearms.
Du Plessis is to testify before the amnesty committee later.