Midwest City police arrived quickly; the store is just a few hundred feet from police headquarters. Huff was one of the first officers who arrived, and he began talking with Wallace.
Clabes said Wallace was not making sense.
He talked of being monitored by former President George Bush and said he was the wealthiest man in the world. He also talked of the Illuminati, an 18th-century secret society popular with conspiracy theorists and mentioned in popular fiction.
Officers escorted Keating and her older daughter to the front of the store and locked the store down while the two officers negotiated with Wallace. At one point, officers gave Wallace a chair, and he sat down, still holding the girl and the knife.
As the negotiations broke down, Huff ducked just out of sight and checked his firearm to make sure there was a round in the chamber in case he needed to take a shot.
Moments later, Wallace began counting down from 60 by tens. Huff can be seen on the video squatting low as Wallace looks toward the other negotiator on his left. As the countdown reached zero, Huff walked to Wallace's side, raised his .40-caliber Glock pistol and fired once into his right temple.
The edited video released by police ends just before the shot is fired.
Clabes said Huff told him he thought Wallace was stabbing the girl the instant he took the shot.
In fact, she was unharmed and was quickly reunited with her mother and sister.
Wallace's family members told police he was diagnosed as paranoid schizophrenic. He was released in 2011 from the Texas prison system after serving 11 years for convictions including drug possession, firearms charges and aggravated assault with a dangerous weapon.
Clabes said in that incident, Wallace fired a gun through a wall that hit but did not kill a child.