The Federal Bureau of Investigation warned Garland Police about Elton Simpson before the event.
And now new video has emerged featuring Simpson.
Simpson is seen on the video speaking about his religion in his own words. The video was posted to YouTube in 2012 by the Phoenix mosque he attended. He compares his faith to weapons.
"It provides for you a form of weaponry, use that weaponry against Shatan," said Elton Simpson in the video.
Shatan means Satan, in the 2012 video he compared prayer to weapons, alluding that his faith could be used to fight the devil.
But no one imagined Simpson would fire off real weapons in the name of his faith.
FBI Director James Corney revealed that investigators were aware of Simpson's extreme social media comments about the Prophet Mohammed Cartoon Contest taking place in Texas. They warned local police that he might show up.
The FBI sent a bulletin that included a picture of Simpson to police, but they didn't know if he was planning an attack, or even that he had left Phoenix.
Simpson went by the Muslim name Ibrahim. The President of the Islamic Community Center of Phoenix described him as polite and positive. But the slain terror suspect had been on the FBI's radar since 2006.
He was part of a federal terror investigation and was convicted in 2011 of lying to federal investigators and sentenced to probation.
The FBI director said the Phoenix field office saw no further indication of any threat connected to Simpson at that time.
It's unclear whether officers on the ground in Texas knew about the FBI warning.
His accomplice, 34-year-old Nadir Soofi was also killed in the shooting.
A security guard was also shot but survived the attack.