In their FAQ, Facebook "claims" that the original admin of a group cannot be removed, but just isn't true. If you give access to a trusted friend, and then their Facebook account gets hacked, they can remove all the admin and insert a new one, taking full control of the group. [video=youtube;4LSKEoXJUDY]http://www.youtube.com/watch?v=4LSKEoXJUDY&feature=player_embedded[/video] And a full explanation in what happened in our experience.
Yeah I noticed this awhile ago when one of my groups was hijacked. Did you bother to report this to facebook?