As I stated in my other post DH is hiring a Private investigator to try and prove his SD19 is no longer living with BM( READ OTHER POST FOR FULL INFO)

This being said it's going to cost $$$$ so the more "basic" information we can find ourselfs the less work the Private investigator will have to do to prove our case. 
 

So I'd like to hear everyone's Opinion on the best people search engines. Looking for any info that will help us find where SD19 is living with her BF. Free is best BUT I don't mind paying some if they are good. We can provide names, Social security numbers, birth dates and last know address.