De Kock, the commander of a special counterinsurgency police unit during apartheid, faced the inquiry in the southern city of Gqeberha, where the Cradock Four were killed. He appeared at the hearing as South Africa continues renewed efforts to confront atrocities committed by security forces during decades of forced racial segregation that critics say went unpunished.

The inquiry concerns the 1985 deaths of Matthew Goniwe, Fort Calata, Sicelo Mhlauli and Sparrow Mkonto, three of whom were teachers. Authorities said the men were abducted by police at a roadblock and later found burned, in what has been described as one of apartheid’s most notorious killing cases.

During his testimony, de Kock denied involvement in the prominent case of the Cradock Four. He told the court that police at the time had photos of around 6,000 anti-apartheid activists identified as “known terrorists,” and that the activists should be tracked and killed if an arrest could not be carried out.

De Kock also testified about purported attempts to conceal what police did after the killings. He said one of the officers implicated in the case asked him for assistance with a cover-up, telling the court, “He wanted to know if I could get another firearm,” and adding that he was asked “if we could interfere with the ballistics.”

De Kock is serving as a central figure in the proceedings partly because of his earlier conviction history. He was sentenced in 1996 to two life terms and another 212 years in prison after being convicted of murder, kidnapping and other charges tied to the abduction, torture and killing of anti-apartheid activists, according to the testimony reporting. He was released on parole in 2015.

The hearing also addressed how de Kock was presented in court materials. His age is 77, and the court gave him a police guard to the courtroom. His image was blurred on an official video broadcast after the judge ruled that he not be shown, the Foundation for Human Rights said through its representation of some victims’ families.

The Cradock Four case has been the subject of multiple investigations since the era of apartheid ended. Two inquiries conducted during apartheid were widely suspected of being cover-ups: one began in 1987 and concluded the men were killed by unknown people, while another began in 1993 and concluded they were killed by unnamed police officers. The latest inquiry was launched last year after families pressed for it.

South African authorities said the six former policemen implicated in the killings were never prosecuted, even after being identified and denied amnesty during the country’s post-apartheid Truth and Reconciliation process in the late 1990s. All six have since died.

The testimony comes as South Africa has reopened other investigations into apartheid-era killings in recent years, including the 1967 death of Nobel Peace Prize winner Albert Luthuli, the 1981 killing of lawyer Griffiths Mxenge and the 1977 death in police custody of anti-apartheid figure Steve Biko. President Cyril Ramaphosa ordered a separate inquiry last year to examine whether post-apartheid governments led by his party intentionally blocked investigations and prosecutions of apartheid-era crimes.