What makes you think he's headed for Mexico?
Do you also think every person named O'Rourke who commits a crime in this country is illegally here from Ireland? Every criminal named Rosskovsky is a fugitive from Russia?
FYI, Hispanic people have been in the southwestern USA since the 1600s. Every inhabitant of the region became an American citizen after the USA annexed the region when a treaty with Mexico was signed after the Mexican-American War in the late 1800s.
You may be surprised to hear this, but even American citizens born here have been known to commit crimes, including murder.