Testifying before the commission's human rights violations committee hearings in Tembisa, Nxaba's mother, Fakiswa Malose, 61, said she was constantly harassed by the police after he died.
"They threw teargas through my window."
Malose said several witnesses to her son's death said a policeman called Joe Mamasela, whom the community called Scarface, had killed her son.
"This Scarface is known to have a terrible attitude towards children - especially the comrades. He killed many of them," she added.
Malose said the death of her son was a great loss to the family because they expected the deceased to work for them.
Pensioner Sarah Mnyele, 76, asked the commission to find the remains of her son, who was killed by SA policemen patrolling the borders of Botswana and the Bophuthatswana homeland.
Thami Mnyele, a political activist and an artist, was shot 24 times and his house was bombed in Tlokweng, Botswana on July 15, 1985.
She said Thami, a member of the African National Congress who fled to Botswana, was apparently on the security forces' hit list. Mnyele said he was killed while returning from military training in Tanzania.
"Thami and other Mkhonto weSizwe soldiers were not using normal routes and unfortunately the policemen patrolling the borders got them.
"Those who survived the attack said they (policemen) pumped lots of bullets into his body".
She found the bodies of her son and thoses who died with him at a mortuary in Botswana.
Mnyele added: "I hate a white man. I don't care for him. How can they kill my son like that? I will never forgive a white man until I get my son's remains or at least those of other victims of the attack".
The Tuesday hearing adjourned and on Wednesday testimony will centre around the activities of the notorious "Toasters" gang, which colluded with hostel dwellers and terrorised Tembisa residents in the early 90s.