Another old anon here
Have an old friend who became a metro county cop. He was pretty smart, became a detective while still pretty young. The bureau put him in their Crimes Against Children unit. Policy was to never leave an officer in that unit for longer than one year, because it was so mentally and emotionally draining on personnel. He got out of there and had a tough time with what he'd seen. Got certified as a diver and went to the county underwater specialty crew after that.