The ideal detective is older, of larger stature and higher intelligence than the suspect; and should portray an image of confidence and relaxation. The suspect invariably remains calm during the primary interview, and because he craves attention may prattle for hours. He will try to manipulate the conversation, especially if he believes the detective is being friendly towards him. The interview needs to be conducted in a formal setting and with professionalism. Questions should be planned and structured so that the suspect cannot answer with a simple "no". A sexual sadist will probably attempt to anger, antagonize, or even shock the interviewer. Any demonstration of human emotion by the detective could undermine the interview; the suspect will view this as a victory and as further proof of his superiority.
It is essential that law enforcement officers understand the distinction between cruelty and sadism. A lot of your "impulsive" offenders are physically cruel to victims and may resort to violence during commission of a crime. The sexual sadist intentionally and methodically cruelly victimizes others for the sole purpose of self sexual-arousal. The sexual sadist is essentially the great white shark of sexual crimes. He is the ultimate predator. These criminals are ritualistic and psychopathic offenders who have no conscience.