A police officer stopped accused Arizona gunman Jared Loughner a few hours before he allegedly went on a now infamous shooting spree that severely wounded Rep. Gabrielle Giffords and killed six others.
Investigators are putting a timeline together of what Loughner did that day.
"What he did and the morning before the shooting, we're just trying to find all that out," said sheriff's Capt. Chris Nanos.
First, he made two trips to Walmart. Nanos would not say what he bought.
On his way home from shopping, police pulled over Loughner at about 7:30 a.m. after he ran a red light, the Arizona Game and Fish Department said. The officer ran a check on Loughner's driver's license and vehicle registration. Finding no outstanding warrants, he let him go with a warning.
At about 8 a.m., Loughner's father Randy said he saw his son walk to one of the family's vehicles and take a black bag out of the trunk. Police are still searching for that bag.
"The father went out and said, 'What's that?' and [Jared] mumbled something and took off running," said Sheriff Clarence Dupnik.
Randy Loughner got in his truck and chased his son, but he ran into the desert.
Police say Loughner took a taxi to a Tucson grocery store where Giffords was holding an event and at 10:11 a.m. opened fire, killing six people and wounding 14 others.