Mexico doesn't have an official death penalty whereas Texas does. To the degree any of those crimes were commited in whole or in part in Texas then Texas would be forced to execute them both.
They have a much better chance with Mexico. They should start packing now. Get in while the getting is good.
Yes, there is. It's called protecting our sovereignty. We're not bound by extradition treaties to extradite our own nationals and we shouldn't set a precedent by doing so in this case. The U.S. Constitution is the Supreme Law of the Land. Our citizens are protected by and have rights under it.
Hatred or dislike of the individuals involved is clouding your good judgment as an American citizen and as a conservative who respects the Constitution.