He can be charged with a crime if the police find sufficient evidence that he's done something criminal.
A written admission of doing it wouldn't be enough.
Anecdotally, it seems that employees who do what your friend did are then tempted to extend their misdemeanors into fraud, e.g. by scamming the betting shop with rolling bets until they win, or by destroying betting slips (not so easy with modern computerised systems).
The betting shop owner and the police will be looking for evidence of him giving in to that temptation. If he didn't, then he's merely breached his employment contract and not broken any law.
Can you be sure that he's told you the whole story?
A written admission of doing it wouldn't be enough.
Anecdotally, it seems that employees who do what your friend did are then tempted to extend their misdemeanors into fraud, e.g. by scamming the betting shop with rolling bets until they win, or by destroying betting slips (not so easy with modern computerised systems).
The betting shop owner and the police will be looking for evidence of him giving in to that temptation. If he didn't, then he's merely breached his employment contract and not broken any law.
Can you be sure that he's told you the whole story?