<p>'If you made me angry, to me, for that anger to go away, I have to get hold of you ... I have to do something to you.'<br>'I didn't feel myself. I felt numb, like a zombie, like a switch had been flicked and a light had gone off.'<br>These are the words of some of South Africa's most terrifying serial killers, who spoke to psychologist Brin Hodgskiss in the bowels of the country's most secure prisons.<br>Hodgskiss interviewed several of the mo...