About Choosing a Private Investigator
When you look at a private investigator's advertisement, be it in a telephone book or a web site, note what they give for experience. Most of the time they will say something like "30 years experience". Ask yourself if they are counting the time they were an investigator for an agency such as a police department. If there is doubt then ask the person.
There is a difference in having "30 years experience" with a police department or insurance agency compared to being a private investigator for 30 years. Take a retired police officer for example. Many retired police officers become good private investigators, but a retired police officer is used to having a big budget to work with. They are accustomed to having access to equipment, records and other resources they no longer have access to when they become a private investigator. They are not used to working with a client who has limited resources. They are used to carrying a badge making them "the man".
Some still have what I call the "Cop attitude". This can be important in a criminal case. They might treat potential witnesses with that type of attitude, which can hurt their investigation. I have seen the results of these attitudes. Most people recognize this type of attitude and know the private investigator does not have the power he had when he was a police officer. Often times they will not cooperate. This can severely hurt a criminal defense case.
I recommend you ask any private investigator you are considering hiring what their background is. If they say they have so many years as an investigator, have them break that down. Ask how long they have been in business as a private investigatior. Ask them what their private investigator license number is and when it was issued. Generally the lower the number, the longer they have been in business.