He sounds like he has no respect for you. And dragging him into time out and bending his fingers back is not going to win you respect. (what kind of psychologist tells you to bend a child fingers??) Apparently time out is not going to work. I would take something away (TV, Video games, whatever is near and dear to him) and don't back down. You have to be tough and serious and if he comes at you in a violent way - tell him you are going to call Child Protective Services and they are going to take him away! (That might make him think!) I do agree with the previous poster that he may be frustrated about something and is taking his stress out on you - but you have to get the respect back before you can help him. Good luck!
You raise an interesting question. You know, I would make an anonymous call to Social Services to ask the question-- I would bet the answer would be different based on local jurisdiction.
It must be very frustrating to have his behavior directed at you. My suspicion is that there is something in his life that is bothering him, and he takes all his frustration out on you because you are safe. He is testing you -- I don't know why people/ children test, but I know that they do.
Has the counselor suggested anything that could be causing his elevated frustration level?