Arizona police say Jared Loughner, the alleged gunman in the Tucson massacre, had 12 previous encounters with authorities over the years, including two arrests for alcohol and marijuana possession.
They added that on the day of the shootings, he was stopped for running a red light, but was let go with a warning.
Friends of Loughner, 22, said he once took hallucinogenic drugs and was angry at the government, but that his displeasure was not directed at any political party.
"He did not watch tv. He disliked the news. He didn't listen to political radio," Zack Olser, a high school friend of Loughner's, said, "He didn't take sides. He wasn't on the left. He wasn't on the right."
Loughner reportedly had a conversation with Rep. Gabrielle Giffords, D-Ariz., in 2007 that angered him.
Meanwhile, two close friends of Giffords, who was critically wounded in Saturday's shooting rampage, reported that the congresswoman opened her eyes for the first time on Wednesday. This was revealed by President Obama during Wednesday night's memorial service at the University of Phoenix.