Unfortunately per whois, domain name first created in 2005 and renewed to 2009. So unless your client bought the domain name himself, he/she could wait for domain name to be free in 2009, get private investigator to look for former web designer, etc. or do something else now.
The same thing happened to a client who left everything up to the web designer who had all passwords and never gave it to client before leaving town. Don't know why the web designer did that to client, up to them. Karma and all that.
Best solution, move on - taught client how to get new domain name and how to get new webhosting; then I set up new website, taught him to buy adwords, set up google map and all that google jazz, got higher ranking than the old domain, bought old domain name when it was not renewed by former web designer and pointed it to new website. Does this make sense to you?