wow, just wow! instead of learning from your methodologies and improving his skillset, he does this.

whelp, i would put some logging in / monitoring the server / lock his account, etc., but prove his account is doing this / what times, etc., then go to him with it (not the boss, no one likes a tattle tale) and tell him next time you'll take him to the boss, yourself, and let him decide what to do with the guy.

Or, can...