No one was exempt from being charged. The South African police were charged, ordinary people could be charged, but most notably members of the ANC, the ruling party at the time of the trial, could also be charged.
The commission brought forth countless witnesses giving testimony about the secret and immoral acts committed by the Apartheid Government that many say would not have come out into the open otherwise. Since this commission, similar comissions have sprung up in other countries, although not always with the same scope or the allowance for charging of those currently in power.
There is a film about it, featuring very amazing confrontations.