If the number is small, and items were deleted normally (to deleted items) then they will still exist if you have deleted item retention enabled on the database.
To purge these, you would go into the mailbox, open deleted items and select recover-deleted-items. When you see the target message you purge it.
An alternate method (may be too late now) is to use EXmerge to remove the message. You enter the specifics of the message in the filter and it can take the message out of all mailboxes in one go. This is the way large spam or virus-sent messages are cleared out of the system.