Eliza. I don't honestly know if I could do this or not, but it does not really matter when there are people who would do it as a profession. Much the same as I would not work in a slaughterhouse yet I eat meat. I use a lavatory, but would not work down a sewer.
If we disregard the terrible miscarriges of justice (a big ask, I know), would you be prepared to explain to the parents of a tortured, raped and murdered child that the person who did this was known to the police and had already served a sentance for a similar offence but was released when his time was done?