He walks into the accounting firm and asks the receptionist for Arthur Brandt's office. His office was about 10 feet away with a huge sign on the door with Brandt's name on it.
sharePerhaps he didn't notice. However it is more likely that he was just following normal protocol. Generally one does not go to an office where a receptionist is in place. The polite thing is to go to the receptionist and either ask to speak to the person you are looking for or ask fro their office. Either is valid.
shareAlso, this is Columbo. He has a way of doing things, even if he knows what's going on, to make it seem like he's not exactly running with all cylinders or have a lot of common sense. Why should he do the direct route, when his style gets him to have more conversations, meet more people, which means more information, more opportunities and possibilities, more clues and so on.
If you can go the 'pure info route' or the 'friendly conversation route', you should always take the latter if you want more information, you never know what someone might know or slip out that might come useful later on. Besides, Columbo clearly LIKEs talking to people, and wants to keep his social engineering tools sharp.