Nkosi Thandiwe, 23, who is charged with murder, gave a detailed description of the shooting while saying that at the time he did not know what he was doing, The Atlanta Journal-Constitution reported. He is charged with killing Brittney Watts and with shooting Tiffany Ferenczy and Lauren Garcia, who was left paralyzed.
The defense rested after Thandiwe's testimony.
The shooting in 2011 occurred in the parking garage of the Proscenium building, where Thandiwe was working as a security guard for Allied Barton Security Services. He said he encountered Watts while he was on his lunch break and drew his gun.
"She got out of the car and started running away," Thandiwe said. "I fired the gun."
Thandiwe said he had been filled with rage by the argument just before he went to lunch.
"My mind was blank at the time," he said.
He became angry when Leah Dunikoski, the prosecutor, suggested on cross-examination that he had hit Watts, causing bruises to her body.
Thandiwe left the garage driving Watts' car.