Updated

A South African hospital says a former commander of an apartheid-era police unit that killed black activists has died of kidney failure.

Dirk Coetzee died Wednesday, said Ineke Jonker, spokeswoman for the Life Wilgers Hospital in Pretoria. He was 57.

Coetzee fled South Africa and switched his allegiance to the anti-apartheid African National Congress in 1989 after confessing he had belonged to a covert group known as Vlakplaas that murdered ANC members.

He returned in 1993 and was a witness at the trial of former police Col. Eugene de Kock, the highest-ranking police official convicted of crimes during the white minority rule that ended with democratic elections in 1994.

Coetzee was granted amnesty in 1997 by the Truth and Reconciliation Commission, a panel that heard testimony about human rights violations under apartheid.