Just because someone is of "middle eastern decent" does not make them a terrorist, nor does it make them immune from committing other "regular" felonies (i.e. robbing banks, cheating on taxes, etc). As the other poster said, DHS is probably taking that Secure Flight data and running warrant checks. Theory 2: The person is on the run from the law, was able to get a last minute flight out of San Antonio; the San Antonio police were not quick enough to nab him before getting on the plane, but called their counter-parts in Atlanta to pick him up on landing.