Although I agree with you to some extent ahmskunnirt it's not as easy as that. In some cases fear takes over and they let the culprick back.
I was assaulted by my ex on a few occasions...the police didn't even give me the option to press charges. They just took him away from the family house and dropped him off at his mates...and I never heard from them again. That was after getting a 999 call from a child.
Shabnam...there sre different types of social workers. If they are happy with you and your child they will allocate a family support worker. These social workers do not deal with kids at risk but try and help families get their life back on track.