I knew a cop who did it for a few years until he felt that it was seriously undermining his ability to trust and relate to other human beings. His team caught all sorts of people, including an Assistant DA (and some women, as well).
Being able to do it for 27 years is amazing, but professionals like this are very good at compartmentalizing and keeping their work and personal lives apart and also at keeping their eyes on the goal, which is to protect children. When they feel they can’t handle it any more, they leave the unit.
The most frustrating thing is the trivial sentences a lot of the offenders receive, and the fact that judges are often very careless about protecting the victimized children
Sex crimes do take a toll on the investigators. I only do a few of these investigation each year. I’ve found that I need to go punch and kick the heavy bag in the gym of our police station before I can go home to my family. It’s like draining the poison out of me so that it doesn’t have a chance to take hold. Terrible.