Two kinds of cases have disturbed me the most. The first is the remorseless killing of children for no apparent reason, beyond the sheer act of killing. The second is the one I call experimentation, where a serial killer will keep a victim for a period of time, during which they carry out gruesome "experiments". One of the most horrendous examples of this is the case of Robert Berdella, known as the Butcher of Kansas City. What he did is partly documented in my book and is also available on the Internet. This was the most graphic of experiments and affected me deeply. Most serial killers who keep victims for a period of time, are remorseless, seeing their victims as a scientific subject, like a lab rat, and having no understanding of the humanity, pain and suffering of the victim.