"He pointed his weapon at the deputy," said Michael T. Ayers, the special agent-in-charge of the Georgia Bureau of Investigation's Thomson bureau.
Kevin Pao, 22, had just been escorted out of Five Guys Burgers and Fries on Monday and was seated in the back seat of Richmond County Deputy Walter Garrison's cruiser.
Pao was not in handcuffs.
"This person was never under arrest," Ayers said. "He was being held under investigative detention at the time -- a very routine process in calls like this one."
When Garrison asked him whether he had a weapon, Pao pulled a gun out of a bag on his lap and pointed it at the deputy, Ayers said.
Garrison immediately drew his gun and fired at Pao, but Ayers wouldn't say where Pao was hit.
Also not disclosed is what happened during the struggle between Pao and Garrison and how many times Pao was shot.
Pao was pronounced dead by a deputy county coroner at 6:20 p.m. Monday.
Garrison, a rookie deputy who started at the sheriff's office in April, was sent to Five Guys about 5:30 p.m.
Garrison is now doing a desk job while the GBI investigates. Ayers expects the probe to be completed and ready for review by Augusta Circuit District Attorney Ashley Wright in the next few weeks.
On Wednesday morning, deputies discovered a sport utility vehicle belonging to Pao in the nearby Kroger parking lot on Washington Road. Investigators think he drove from Maryland and was living in it.
"This man was homeless, from everything we've been able to learn," Ayers said.
An autopsy was performed at the GBI Crime Lab in Augusta on Wednesday, but preliminary findings have not been released to the public.