What is the most accurate way to check someone's background? Urgent!!!?

[plys]

I need to run a background check on a person that lives in another country, but was born and raised in the United States. When this person lived in the United States, they lived in a state different from the one in which I currently live. I am not trying to be nosy, but rather suspect that this person may have gotten into trouble with the law here and decided to leave the country. I have no problem with people wanting to start over, however I now fear for the safety of my family overseas. This person has displayed very disturbing behavior and I would not put it past them to cause someone's death in order to obtain what they want. Many online sites are available, but seeing as this is a very serious matter, I need something reliable and thorough. Would a private investigator be better? What is the best and most accurate way to find out information on this person? I know their full name, previous address and phone number, age, spouse's name, email, place of birth, and names of several states where they resided at some point in their life. Thank you in advance.

[thacher]

Check this site for comparisons of different background check websites:

http://background-check-services-review.toptenreviews.com/

[orlondo100]

Sounds like you should be contacting the cops from the state the person fled.