I agree with the people saying that if he DID cheat, and only does well because he cheated, it will catch up with him - eventually. Because he will not be as good at the subject, as he is going to appear to be (IYSWIM.)
It's like when my kids were doing GCSEs (a few years ago, when it was 50 or 60% course work,) the school were trying to 'look good' in the eyes of OFSTED, and the teachers were instructed to help the kids that weren't so academic. And by 'helping,' I mean by doing most of their course work for them, to make sure that they had an 'A' in the course work. Then if they got an E in their exam, they would have an overall 'C' grade...
So loads of kids left with high C and even low B grades in their GCSE's, when they should have really have had high and low D's, and even E's.
It caught up with them though in college, when they couldn't do their A levels. They got no help there, and struggled massively, and some had to drop out. Some were made to leave, as they didn't even make it to a low E in their A.S's. (the first half of the A level.)
(My kids never had any help, and did everything themselves, and got high B's and A's in their GCSE's, and consequently went on to do well in their A levels...)
Report this lad if you wish, but I'm not sure how you can prove it now.
Let him stew in his own juices. If he DID cheat, then he is lying about his abilities, and he will take a massive fall; eventually.