Just to repeat what I've said before (I'll be brief):
* it's not possible to prove either way whether he's cheated over the board
* under the principle of "innocent until proven guilty", we shouldn't say he's guilty.
I have recently noticed that in fencing, the plastic wire covers in the handle have become transparent:
I had thought this was style - but last weekend I attended a fencing equipment maintenance course, and was told that the reason is that at a top competition, a fencer had been found to have built a tiny remote control into the handle, hidden by the old style plastic covers!