I turned off firewall for about a week. How do I find out if someone hacked into my computer?

The person I suspect of hacking knows me very well, and is VERY smart with computers. He does not use the same network that I do. I am almost 100% positive that he got unauthorized access to info in my computer... and just want to know how to find a "footprint" of this... to see if someone did in fact hack... and if so, can I find out if it was him? Just asking him is NOT an option. THANKS.