MrsSnape, I have no good advice for you, but I just wanted to say there was a David in DD's class at her old school, she was physically attacked by him on more than one occasion, stabbed in the arm with a pencil, he jumped off a bench onto her back with his knee, would swear and fight and ugh, he was a horrid little boy.
I overheard his mother and his father discussing how they would put him and his cousin (who was the same year as him at school) in a room and teach them to fight each other, the one who cried first was the 'loser'
I mentioned it time and time again, but the teacher didn;t seem to say anything except 'yes, we are aware of David's behaviour' turns out the school were trying everything possible not to have to exclude him because they knew if they did his life would probably never have any path to follow, but every thing they tried his parents would counteract, the teacher was even taking stick at the classroom door from his family for claiming that she was 'picking on David' and making an example of him
I'd say go and speak to the teacher, everytime something happens, they need to know how much is going on, but I doubt there will be muich they can do, sadly as his family probably aren't exactly supportive either.
Poor kid