A police commander known as “Prime Evil” testified in a South African court about the killing of people during apartheid.

One of South Africa’s apartheid police chiefs testified Monday at an inquest into the killing of four activists in 1985 as part of the country’s renewed focus on brutality by the security forces amid decades of unpunished apartheid.

Eugene de Kock, dubbed “Prime Evil” for his role in killing anti-apartheid activists, denied involvement in the landmark Cradock Four case – but said police at the time had photographs of around 6,000 anti-apartheid activists who were described as “known terrorists” who should be tracked down and killed if not arrested.

The Cradock Four were not among them, he said. Mr Matthew Goniwe, Fort Calata, Sicelo Mhlauli and Sparrow Mkonto, three of whom were teachers, were abducted by the police during a roadblock and died. Their bodies were found burnt, in one of the most shocking crimes during apartheid.

De Kock revealed that one of the police officers involved in the murder asked him to help cover it up.

“He wanted to know if I could get another shot,” de Kock said, adding that he was asked if it would “interfere with the ballistics.”

De Kock, who was the commander of the anti-insurgency police unit during apartheid, was sentenced to two life terms in 1996 and another 212 years in prison after being convicted of murder, kidnapping and other crimes for his role in kidnapping, torturing and killing activists. He was released on parole in 2015.

According to BBC News, his father, Lawrence de Kock, was a magistrate and close friend of former apartheid Prime Minister John Vorster. His brother, Vossie de Kock, described him as a “quiet boy” who was “not violent at all,” the BBC reported.

De Kock has asked for forgiveness from some of his victims, according to the BBC. In a letter he wrote to the family of Mr. Bheki Mlangeni, the lawyer who killed him with a bomb, he wrote: “There is no punishment greater than life and the consequences of a heinous act and no one will forgive you. For me, even my death does not compare.”

Now, 77-year-old De Kock has been given custody at the courthouse in the southern town of Gqeberha, where the Cradock Four were killed. His image was blurred in an official video broadcast after a judge ruled that he could not be shown, according to the Foundation for Human Rights, which represents some of the victims’ families.

Two questions about the crime committed during apartheid were widely suspected of being a cover-up. One that began in 1987 found that the men were killed by unknown people. Another, which began in 1993, found that they were killed by unnamed police officers.

The latest investigation began last year after pressure from the families. Six former police officers involved in the killings have never been prosecuted despite being identified and denied amnesty during South Africa’s post-apartheid Truth and Reconciliation process in the late 1990s. All six died.

South African authorities have opened yet another investigation into apartheid atrocities over the years. They include the death of Albert Luthuli who won the Nobel Peace Prize in 1967, the killing of lawyer Griffiths Mxenge in 1981 and the death in 1977 in police custody of apartheid star Steve Biko.

South African President Cyril Ramaphosa last year ordered a separate investigation into whether the post-apartheid governments led by his party deliberately obstructed the investigation and prosecution of apartheid-era crimes.