But Forney was worried whether Loughner could drive safely.
"I again made sure that he was OK. I asked him ... three or four times. He was probably getting tired of me asking if he was OK," Forney said.
"He said yeah, he was fine. He was just heading home, it wasn't too far away and he'd be OK," Forney said.
Two and a half hours later, Loughner opened fire on a crowd of people at an outdoor event where Giffords was greeting constituents.
When Forney got home that night and heard about the shooting, he went online, he said.
"I opened up the Internet and there was his picture," Forney said. "Man, my heart just went up in my throat."
About an hour after the traffic stop, Loughner returned to his parents' home in his 1969 Chevrolet Nova, his mother, Amy Loughner, told authorities.
When his parents asked him what was in his backpack, he ran out the door, his mother said.
His father, Randy Loughner, dropped his coffee and ran after his son but couldn't catch him, the mother said.
A short time later, a neighbor told them there were news reports Giffords had been shot.
They later learned from authorities their son was believed to be the shooter.
Kenneth Veeder, a bystander to the shooting, suffered a gunshot wound to the calf as he was talking to a family lined up to meet Giffords. Veeder, a Vietnam War combat officer who served three tours of duty, was wearing an Infinity Airborne shirt.
"I heard pop, pop, pop, pop," Veeder said.
Loughner was running and knocked him down, he said.
When Loughner was reloading his gun, one man grabbed him, and Veeder grabbed Loughner's gun that fell to the ground, Veeder said.
Veeder wanted to reload the gun, but a woman talked him out of it.
"She goes, 'You can't do that,' " Veeder said in the transcript. "The hell I can't -- because I would have shot him. That's how angry I was. It was a combat reaction," he said.
Deputy Sheriff Thomas Audetat Jr. recounted how he arrested Loughner. He saw two or three people holding down Loughner on a sidewalk between a Safeway grocery and Walgreens.
Audetat put his knee on Loughner's back and handcuffed him.