However, asking someone to admit a fault worthy of punishment wouldn't be easy. Would a criminal admit his crimes? No. I think not.
Then how'd you suggest we could link that telegram account to a Bitcointalk account? we can't just tag somebody based on similarities between telegram username and forum username.
Totally agree. I don't really have any other suggestion on how should we address this matter but i'm just saying that making him say that he's guilty of his crimes would be hard. Anyways, OP, you should try and ask him personally. Or just trick him into revealing his identity (should be plausible).