Whether he was in trouble with the law or not is irrelevant to the school’s losing the paperwork.
A *clash between children* could mean anything. Some other parent could have not liked the way her son looked at her little darling, or he could have pulled a knife on someone. Who knows?
She says the school lost the paperwork, but she's apparently not able to show that she actually turned it in either.
Now I don't know. Maybe she did turn it in as she said she did, and maybe the school did lose it.
What it sounds like to me - and we're only getting her side here - is that at least one child had too little supervision, and thus got the attention of the police, who began to wonder why he was unsupervised.
I will admit that it's speculation, based on an article which has only one side, and too little information.