Madikizela-Mandela was testifying at the Truth and Reconciliation Commission in Mayfair, Johannesburg, about her alleged involvement in human right atrocities in Soweto in the late 1980s.
Nicodemus Sono told the TRC last week his son was brought to his house in a kombi on November 13, 1988, by Madikizela-Mandela and several of her bodyguards from the Mandela United Football Club. Nicodemus Sono said he had pleaded for his son's life.
Madikizela-Mandela denied ever having gone with Sono to his father's house.
She said on Thursday she had used Sono as a courier, or go-between, between two Umkhonto we Sizwe cadres who were hiding in the home of Jerry Richardson, the football club "coach".
Both cadres and Richardson's security branch police handler were killed in Richardson's house on November 9, 1989, when the house was attacked by police. One of the cadres was Sono's cousin.
The commission has heard Sono was killed after Madikizela-Mandela branded him a police informer. Richardson has claimed he killed Sono and another missing youth, Siboniso Tshabalala, on Madikizela-Mandela's instructions. The bodies of the two youths have never been found.
Madikizela-Mandela said she had made no attempt to find out what had happened to Sono after his disappearance.
TRC chief legal adviser Hanif Vally said he found it curious that Madikizela-Mandela had not tried to find out what had happened to a courier she had trusted implicitly who had disappeared in strange circumstances.
Vally read a statement Madikizela-Mandela made at her TRC in camera hearing in September. She had said then: "Why should I have run around looking for Lolo?"
Madikizela-Mandela did not want to revise her statement in September, except to say that, during the time, she was not in a position to make inquiries. She thought the youths went to Lusaka.
Vally pointed out that a witness who it was believed could corroborate Nicodemus Sono's testimony had allegedly been intimidated by a person believed to be Madikizela-Mandela or one of her associates.
TRC investigative consultant Piers Pigou told the commisssion on Monday he had met a Michael Seakamela, who told him he had driven Madikizela-Mandela and Sono in the kombi to Nicodemus Sono's house.
Pigou visited Seakamela on Saturday and, during their conversation, Seakamela refused a phone call from his brother, Oupa Seakamela, who had spoken to "Mami" (Madikizela-Mandela). Oupa Seakamela is the father of one of Madikizela-Mandela's grandchildren.
Vally said the commission had also heard about a statement made to the Attorney-General by Michael Seakamela in which he corroborated Nicodemus Sono's testimony about the visit.
A former football club member Katiza Cebekhulu told the commission last week he had also travelled in the kombi to Sono's father's house. He said Sono had asked to go to the house because there were documents at the house which could prove his innocence.
Vally asked Madikizela-Mandela whether, with all this evidence, she still denied the events took place.
Madikizela-Mandela said: "There was no such event, no such incident."