delete guest posts

[pantani]

Hello,
I had to delete someone's account in a hurry, because of some major problems at home, i will not go in to detail with this, but now i have to delete this members posts, and you can not find the post under his name offcource, now all the posts of this person are with his name, for example "Jim" and under his name is Guestn so you can not find the posts "Jim" posted.
You have to look in topic per topic to find if he made a reply somewhere and delete it, so you can see this is impossible to do like this, so now the question, is there a way to delete all his post in one time?? But can't search his name because it's account is deleted.

Thank, hope there is a way