I am using cyrus for imap and pop

One of my users is getting the following error: Unable to lock maildrop : Mailbox is locked by POP server.

I can see where it starts in the log. I've read that there is no physical lock file anymore (i've tried looking for it anyways) and that the solution is to just wait for the timeout, or kill the offending pop3 process. I know that this is happening because of a lossy connection on the part of the affected user, and that pop3 can only have 1 session active at a time. I need to manually clear the lock and I am having trouble finding the offending pop process. I have tried lsof, but it doesn't say how long the individual files (sockets) have been opened for. I've reduced the tcp keepalive time down to 5 mins, but I still need to reset this guy's lock. I could use some pointers. Thanks!