Just saying that you found the user was abusing the bonus system and multi-accounting isn't good enough IMO. You guys need to provide proof with in this thread or privately with a trusted member. Your site hasn't been around long enough for the forum to just take your word.
I support this, you have to establish the fact that OP is cheating since you are a new casino, it's for your reputation too that you are transparent and you deserve the trust of the community based on your words and it should start here, if you cannot what will make us believe that in the future if a similar situation happens will you just tell the community with the similar statement and expect that the community will take it as a fact.