The guy at the origin of this thread is, according to my family in Ireland, to be deported in the coming days. This reassures me on 2 counts - 1/ he no longer has to endure the barmy US prison system (serving time 1,500 miles away from where you do the crime in a private prison) 2/ proof that the assault that caused his problems in the first place was a very minor one indeed - it look like charges have not even been pressed - as I understand it US law insists that if an offence has been committed by an 'illegal' the sentence is served in the US before deportation. Ergo, his original offence seems to have been a minor one indeed.
Thanks again to those who gave advice / PMed me.