If you are still on the server and can prove it was his account and not someone framing him then this would be sufficient proof. If you are still on the server and so is he, Please take a screenshot of his profile in the tab menu. (scoreboard)

If you are still on the server and can prove it was his account and not someone framing him then this would be sufficient proof. If you are still on the server and so is he, Please take a screenshot of his profile in the tab menu. (scoreboard)