Outgoing IT Staff: Security Concerns

[glatt]

I'm not in IT, so I have no idea, but I'd guess that there's very little you can do to be sure everything remains secure.

This person could have taken a list of all accounts and passwords home. Even if you disable their account, they could access the network under a different one. Is remote access allowed now, or do you have to be on site to gain access to the system? If remote access is allowed, I don't see how you can guard against them using another account to get in. You just have to trust that their professionalism and fear of legal problems will keep them from doing anything to hurt you.