Christie wrote of his difficulties in finding monsters.
“Once I was supposed to meet a guaranteed monster. I went to see him and met a man like most men. … My search tells me that it seems possible to understand nearly everything without preconceptions that offenders are outside the human family.” (Quotation from ‘Roots of a Perspective’ in Thinking about Criminology edited by Simon Holdaway and Paul Rock (1998), London: UCL Press: 122.)
Relatedly he warned against condemnations pretending to be explanations.
“Evil people are their own explanation. The discussion comes to a stop, the phenomenon is understood, there is no further need for intellectual efforts. … Also, with evil people the next step becomes close to obvious. They have to be eliminated. War is the natural answer. War and extermination.” (A Suitable Amount of Crime (2004), London: Routledge: 49)
Denunciation interferes with explanation (and therefore wise prevention) and can lead readily to brutality.