Child's Father Took Her to Mexico

This is a situation that I could use any advice or suggestions on what to do
This mother was getting a divorce from a husband that at the time was a illegal from mexico. He talked her into going over to mexico with him so the daughter could visit with his parents(her grandparents). Once over in mexico he took the mother's and daughters passports. The daughter called her mother here in Texas and got new passports. But the father refused to let the daughter come back to the states. The mother came back to texas and finalized the divorce with full physical custody of the little girl. She could find no one that would help her. Meantime the father has been coming over to texas to work and has been seen by many people. They received a tip that the daughter was here and so they called the authorities
to try and get the little girl but someone in the dispatchers office tipped him off and he fled back to mexico. My question is what can be done to get this little girl back together with her mother? The authorities are telling her that this is a civil matter. Isn't there anything that can be done as he is denying the mother from seeing her child. It's seems outrageous that he can continue to work over here in the states and still keep the daughter from the mother. I would appreciate any solutions offered.
thanx Debi

This may be oversimplified, but, go get her?
They cant be that far into mexico, if he's coming back and forth to work.
Get the girl another passport, get in the car, get a couple large muscular friends, and take a road trip.
I don't know how cooperative the mexican authorities would be, but stop at the police station on the way to the house.
Oh, and bring the divorce paperwork with you.