Loughner's guilty plea enabled him to avoid the death penalty. He is serving his sentence at a federal prison medical facility in Springfield, Mo., where he was diagnosed with schizophrenia and forcibly given psychotropic drug treatments to make him fit for trial.
Loughner's attorney, Judy Clarke, didn't return a call seeking comment Wednesday. There was no listed telephone phone number for Randy and Amy Loughner.
Arizona's chief federal judge and a 9-year-old girl were among those killed in the rampage. Giffords was left partially blind, with a paralyzed right arm and brain injury. She resigned from Congress last year.
Giffords intern Daniel Hernandez described how people were lining up to see Giffords on the morning of the shooting. He helped people sign in and recalled handing the sheet on a clipboard to Loughner.
"The next thing I hear is someone yell, 'Gun,'" said Hernandez, who rushed to tend to Giffords' gunshot wound to the head.
"She couldn't open her eyes. I tried to get any responses from her. It looked like her left side was the only side that was still mobile," Hernandez told authorities. "She couldn't speak. It was mumbled. She was squeezing my hand."
Hernandez explained how he had some training as a nurse and first checked for a pulse.
"She was still breathing. Her breathing was getting shallower," he said. "I then lifted her up so that she wasn't flat on the ground."
When he was arrested at the scene, Loughner was wearing peach-colored foam earplugs and had two loaded magazines in his left front pocket for the Glock he used in the shootings.
Hours later, he was polite and cooperative as detectives began their initial interview.
As Loughner sat in restraints in an interview room, the conversation was confined mainly to small talk. Little was said over the first four hours. Loughner asked if he could use the restroom, then at one point complained he felt sore.
"I'm about ready to fall over," he said.
Today, Giffords is still recovering. She struggles to speak in complete sentences and often walks with the help of her husband.
In a January interview on ABC News, she said "daggers" to recount her tense, face-to-face encounter with Loughner at his sentencing. When asked to describe his mental illness, she said one word: "sad."