Very first episode shows a woman's full frontal nudity very, very briefly. It's a "bink and you'll miss it" moment.
Some of the earlier episodes had story arcs about Frost's love life. Sex is implied but never seen.
Some of the cases include adultery, rape, incest, molestations and sex in general.
Rarely any nudity except for the shirtless men and their buttocks in the football dressing room in episode "Dead Male One".
In one episode a 15 year old girl is raped (the actual rape is not shown) and she recounts the experience to the police later on. This is very upsetting and hard to watch.