re: Anyone know how to track a document, word, excel, etc...

If you're a big dick at your company then you could probably have the IT dept check their emails from the server to see if they forwarded it.

if they were smart they wouldn't have forwarded it from their work account but instead sent it from a personal email based email account (Gmail, Yahoo, etc.) but most people aren't that smart and there's a chance they were sloppy. Most company handbooks state that your email is not yours and that the company can look through it anytime they want. IT could probably do this from a remote location or check the Exchange Server and the suspected person would never know.