I don't know if BD has ran to Mexico or not, but this is pretty interesting reading if she did:
https://www.texasattorneygeneral.gov/files/cj/article4.pdf
The above is a link is the Mexican Federal Penal Code and criminal prosecutions including extradiction.
I have no reason to doubt that BD is a US citizen, but from I am reading what will matter is if she was born in Mexico or not. If she were born in Mexico, she can be tried in Mexico from what I am reading. Even if the crime was committed in the US. From the link on page 1: 1If the fugitive is a naturalized U .S . citizen who was born in Mexico, he is considered a Mexican national by the Mexican government, and extradition may not be a viable option . In such cases, a prosecution in Mexico under Article 4 is recommended .
This is going to get real interesting if she has ran to Mexico.