don't turn me in bro
How do I report someone I suspect of cheating?

Debating whether or not to make a report, just a guy who I was playing whose turn-based rating is almost 600 points ahead of his blitz rating, and who has only lost four out of more than 100 turn-based games. Some people are just really bad at blitz though, perhaps he's legit. I don't want to report someone when I'm not certain they're cheating. Opinions?

http://www.chess.com/groups/forum/cheating-forum
is the forum for cheating topics.
I suggest reading the old threads before posting.
Title says it all really. Is there a forum I can use or something?