He will most likely be facing court-martial for a number of spcifications under the UCMJ. Although the military hasn't executed anyone since 1961, Reagan reinstated the military death penalty back in 1984, with a few changes. Bush, just last year, was the first President to approve a military execution since Eisenhower in '58 (for the execution carried out in '61). Sadly, the execution that Bush approved was for a serial killer/rapists who's last crimes were in 1987 or 1988. So, it takes some time, and he's still not dead has his sentence was stayed pending further appeal just weeks before his scheduled execution.
The Akbar case from 2005 is pending it's final mandatory appeal, which should be completed in 2-6 months, which will put it in Obama's court to either approve or deny. Then that decisions, like the 87 case, could be appealed as well.
In short, if he were to be tried under Texas law, which isn't impossible but VERY, very unlikely, he'd be dead probably within 5 years. FWIW.
Oh, and he’ll do his time either on in Ft. Leavenworth at the United States Disciplinary Barracks (death row for the military). Believe me, it’s a much tighter ship than federal prison. Irrespective of how long he waits for his execution, he’ll be very uncomfortable during the process - no TV, no Gym, no Oprah.
How about the Army take this POS back to Fort Hood, blindfold him, put against a brick wall, and ask for volunteers?