First thing you to want to make sure is, the individual is not going to renew it. They are usually given a grace period after domain has expired to renew the registration. If you do a whois on the domain name, it should give you some sort of contact information. Go to the website in question, and see if the site is up and running. If so, email the owner, talk to them that way. If they are not willing to give the domain up, then you either have to wait, or choose a different name.