Any advice on how to find my estranged father who may live in Mexico and may not be a U.S. citizen?

I haven't seen my father in 27 years and have recently decided to start a search for him. My family has no information about him and he often used my mother's social security number when he lived in the U.S. He may not be a U.S. citizen and may live in Mexico. A google search of his name turns up seemingly nothing. Are there any resources that may help me in this search inside the U.S. or in Mexico? I am willing to pay for services. Thanks.Any advice on how to find my estranged father who may live in Mexico and may not be a U.S. citizen?
These questions keep cropping up in ';Family'; because no one seems to know where to put them. When I was at the awards banquet, I met the guy who's a top answerer in genealogy, and that's where these questions should go. Those are the people who are the experts in looking up birth, death, marriage records, the sorts of things kept at the county courthouse. I remember him telling a reporter how he helped a woman find her family, and that was the first it had occurred to me that genealogy would be the place for such questions.





Good luck!