Deleted user won't go away

I'm trying to delete a user on a MBP that has been configured to run mobile homes. It was authenticating against a Mini running SLS. I've deleted the account in both Workgroup Manager and in System Preferences on the MBP. Yet if I type the command "id username" in Terminal, the user's information is displayed. The same command typed on another machine (which is still talking to the server) reports "No such user."

So I think that the user's account/credentials must be cached on the MBP (since the user has been deleted through WGM and the machine is no longer bound to the directory). Does anybody know who to make the machine forget the user? I've tried clearing the caches in /System/Library and /Library.