What do I do if there are still active utilities under someone else's name at my address?

A detective showed up at my home asking how long we had lived there because someone called and informed him that there were utilities active in their name at my address. I told the detective lots of mail comes in the mailbox, but I just throw it away. He went to my landlord, called me at work, and called my young sons at our home. All my utilities are currently in my name, and my uncle has co-signed for my electricity.