If the company denies having any names that you've mentioned over the call, let them know that you have received a call from someone claiming to be from the mentioned company. In warning them, they can bring the matter up with authorities in order to protect themselves. You can also bring the case to a police officer. However to make your point more valid, you can provide the police more information on the call such as time and day you received the call and if you can remember what the caller sounded like, list it in as well so that the report can be investigated. Prior to hiring detectives, find out what these professionals can offer to you realistically. You want to know what types of services they can provide so you can get the answers you need. It is always a good idea to hire a licensed private investigator since this person will have the experience and know-how to help you. Here are a few ways they can do just that. Detective, private investigator, special agent, spy are all names given to a person/s who basically does the investigative work. Special agents and spies basically work for the government agencies and the detectives or private investigators work either for an agency or are self employed. There are numerous fields where we need an investigator. Now-a-days detectives specialize in a particular domain and work only in that area. They train themselves for that field and use modern techniques to solve related cases.