You should choose a Private Investigator who is local. Why? Because you need to be able to contact the investigator and talk to him or her about your case. Most PI's will give free consultation. It is a good idea to meet him or her face to face.
Does it matter if they have an Office or PO Box? Remember, just because a Private Investigator advertises an office address doesn’t mean the Private Investigator is competent or professional. There may be other reasons that they have office space leased or owned. Many Professional Investigators who work from home are highly qualified and prefer to use a PO Box for their correspondence.
How important is their investigation experience? Most investigators are quick to point out what experience and qualifications they have.Many former Police, Federal Agents, Military Investigators, and others go into the private investigations business. Some have a easier time adjusting to the PI business than others, as private eyes are simply citizens who are licensed and have some expertise in investigations. In Texas, at least, PI's are not given any special priviledges that a normal citzen doesn't have. In Texas, for an investigator to have their own company, they must be licensed, insured, and have a minimum of 3 years investigations experience.
Does the Private Investigations Agency have business liability insurance? In Texas to have a license, you must first be insured before you can get a license.
What if they sub-contract some work? Often a private investigator will sub-contract out some of the work. In Texas this is not a particul;alery big deal, as all investigators are required to inform the clients of subcaontractors and give them information like name and contact information and state investigations license number. Where vere you are as a client you should always be aware of what is happening concerning subcaontractors. You should always inform the PI if you agree or disagree with it. If there is an agency that does not do this - I would avoid them. Most of this will be spelled out in the contract.
Can I just do the investigation myself? Yes you can. However, if you do not have the time and/or expertise, you may not be able to get the information you want. If you try to investigate yourself and mess things up, it may be much more difficult, if not impossible fot the investigator to do the job.
Remember, you are the client - it means you need to stay on top of the situation. Let the investigator do his or her job, but stay in touch and make sure they are working for you. Like dealing with most "contractors" using common sense is the first thing. Make sure you use a real licensed insured investigator.
Whatever you do - Stay safe!