Civil Rights Issues: My Son Was Falsely Accused

My question involves civil rights in the State of: My son was accused of stealing at school today from another pupil. He was taken to a separate room and asked to remove his school jumper,tie and shoes while the teacher emptied the contents of his school bag.My son and the boy whose money had gone missing were both late for their P.E lesson, they were the only two in the changing room(apparently?)left to get changed for their lesson . My son left the changing room first to join the rest of his class leaving the boy whose money has gone missing .Break time followed this lesson and it was at this point that the boy realised his money was missing from his wallet . The teachers were alerted and immediately assumed it was my son that had taken it . After being searched no money was found on him! I was also not informed of any of this going on. it was my son that managed to get a text message to me to tell me what had happened. later , when my son finished school he told me that he was not the last one out of the changing room like his teacher said , he was out before the boy. I called the school and asked about what had gone on today and I was told that it had all been sorted that afternoon by conducting a whole class search and then the money was found on another pupil. On top of this, whilst being searched they found a cigarette lighter on him (my son is 16)though he did not have his cigarettes on him , the teacher carrying out the search gave my son '5' lunch time detentions for having the lighter.
My son was singled out and accused before any type of investigation took place and then for his troubles ended with 5 detentions . have the school mistreated my son and if so what can I do about this ?

Civil Rights Issues: My Son Was Falsely Accused