My 4 year old son told me that his father beats him with a "paddle", but there are no marks on him.?

Wow, try getting CPS involved and let them know what is going on while he spending time over there. Let them know that you feel your son is physical danger if he keeps going over. Let them know everything, even the previous restraining orders on the step mom. Don't let people like this get away with crap like this.