If he didn't get any warning emails that isn't a good sign. Sometimes, small web businesses or freelance designers will register the domain names under their own name. It becomes troublesome as if you piss them off or leave them, they can hold it hostage. If that company registered the domain name under their name you will have to contact the registrar.
I have come across a number of new clients who decided to stop using their old designer and had their name held hostage, or like yourself, the designer disappeared and they were left not knowing what to do.
They will attempt to contact the owner who they have listed. If they can't reach him, I think there is some documentation proving you are the business owner you might be able provide them to possibly get it back.I am sure it varies by registrar and with the domain pending delete etc., who knows. Network solutions works in this way but I don't know about the other places.
If you fail to get the domain name directly from the registrar, you should look at
www.snapnames.com. Buy a domain snap which basically attempts to grab a domain name right as it becomes available.
If the domain name isn't that sought after, you have a good chance of snagging it. If someone else has a snap for that name and their snap beats yours to registering the domain, your s.o.l. Most times you wont even get the money back for the snap. Its like 40 - 60 bucks usually. At that point in time you could fight to get the domain back from the new buyer if you have the biz name trademarked but that can get expensive.
check out
http://www.pool.com/viewlist.aspx . Uncheck the tlds that do not apply to you and type in the domain name. With luck the domain will show up with the date it becomes available.
Best of luck with this.