So i was playing Persona 5 and......

A question came into my mind. So the definition of a pedophilia is someone with sexual feelings directed toward children. And i wanted to ask you guys, if someone has this sexual feeling should we arrest them before they do something to kids, or should we let them be until they do something? I got no answers on google so can you guys answer. I think the police should keep an eye on people with pedophilia. How about you?