So I understand that many people admitted to the murder. In South Africa, there was a specific admission to the murder by Craig Williamson, who is a ex-special agent. I don't think that here there is the same phenomenon by which multiple people admit to the murder in a delusional way.

This admission was done as part of the TRC (Truth and Reconciliation Commision). There is no reason here not to believe them. The only thing I can think of is delusions of grandeur, but like I say, I don't know of many TRC revelations being untrue.