Dude was going to get convicted one way or another. He was high on cocaine when he did it, and admitted to his brother that he had killed somebody that night when he came home covered in blood. He gave the cops a BS story, then when they told him his brother had told them what actually happened, the guy changed his story and admitted to killing her.
It blows my mind that our government would try to stop the execution, even if it was only a good faith gesture to Mexico. Especially given how hot the topic of immigration is right now. If it was you or me, they wouldn't give two shits if we were about to get the needle. This dumbass has lived in the US for 30+ years. I'm pretty sure he knows the law here.