As I said before, I didn't do much work in business law, so I'm not sure what the situation might be that the attorney would provide a domain name, but not a company name. It may be that the domain name matches the actual business entity's name, but the online name is different. Try doing a search in WhoIs or BetterWhoIs to see what you can find out about the company who registered the domain name.
Either way, no real attorney would say he represented a client he had not actually been hired to represent.
If you want to try to get a little moer information about the attorney and his/her lawfirm, try looking him up in Martindale Hubble [martindale.com]. They provide a great deal about some (though not all) attorneys and law firms in the US. You may also be able to find some information from the State Bar Association where the attorney practices. Not guaranteed, but again it may help.