How can i find someones gamer tag on xbox live three sixty.?

This guy stole my account and used my credit card number on his account but i kinda know his gamer tag name is there anywhere that lists all the names. The name is an s name and i know its splitzer some thin but if i could just see the name one more time id be able to remember it so i can tell xbox live.How can i find someones gamer tag on xbox live three sixty.?I dont think there is a way, just try to remember the gamertag and add it to ur friends list once uve think uve got it you should add it and hope for the best.