I don't have the links any more but google non custodial rights for school and should get lots of info on the law.
Also look into the state laws and see if there is anything in the family code addressing records access.
And if the individual school won't deal with you, look on line to find superintendents and school board members and involve them.
Now keep in mind you are only entitled to the education record, however that will at least confirm he attends school there. From there you will have to hire a PI to probably watch the school and see if mom drops him off and follow her to her home or work address for service.
Now that she is state side, have you tried looking into custodial kidnapping charges? Do you have some type of court order visitation?