What you said
I would recommend keeping a daily log of all concerns and incidents involving this child. Sometimes people outside your classroom can fail to realise the impact on youyour class and having evidence in black and white can hammer it home.
Have you had a formal meeting with the local authority behaviour support service and asked for advice? They should have someone who can observe and advise you.
The expert view
Huge sympathy to you with this situation. It sounds like you're doing a dreadfully difficult job with a very challenging child.
This child's issues sound beyond the capabilities of a classroom teacher alone to solve. At this stage, you need to become a part of the process rather than the sole guardian of the process. You cannot be expected to both teach this class and manage this child's needs.
I would have said that the parents should have been involved at a far earlier stage in the process but, from what you imply, there are complications that preclude this. I take your word that this is the case, as it would be standard procedure to investigate the background to this behaviour and see if there was an integrated school-home solution.
My advice is to refer the case to your line managers, the senior staff and the designated child protection officer in your school. They act as a conduit and liaison between the school, child services, social services and home. They are also trained to get in touch with the right people. This behaviour may be an expression of abuse at home, a cry for attention, a sign of mental illness - or something innocent.
Tom Bennett is author of The Behaviour Guru and Not Quite a Teacher. Post your questions on: www.tes.co.ukbehaviour.