The parents of the suspect in the shooting rampage that left six people dead in Tucson, Ariz., released a statement Tuesday saying that they don't understand why the shooting happened and that they can't express their feelings in words.
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Special Section: Tragedy in Tucson
"This is a very difficult time for us," reads the statement from Randy and Amy Loughner, parents of suspected shooter Jared Loughner, 22, that was handed out to reporters standing in a shady driveway outside their Tucson home. "We ask the media to respect our privacy. There are no words that can possibly express how we feel. We wish that there were, so we could make you feel better. We don't understand why this happened.
"It may not make any difference, but we wish that we could change the heinous events of Saturday," the statement continues. "We care very deeply about the victims and their families. We are so very sorry for their loss."
Both parents have been interviewed extensively by the FBI as part of the investigation into Saturday's shooting in which six people, including a federal judge, died and 14 others, including U.S. Rep. Gabrielle Giffords, were wounded.
Earlier, the parents told federal investigators they knew their son was becoming increasingly troubled but were not aware how much he had drifted and were "completely surprised" that he actually committed a violent act, a law enforcement source told CBS News investigative producer Pat Milton Tuesday.
Teachers and classmates at Pima Community College were not surprised. They said Jared Loughner often laughed to himself, shook his fists and was incoherent, CBS News Correspondent Ben Tracy reports.
Math teacher Ben McGahee said when Loughner wrote the words "mayhem fest" across one of his papers, he called a counselor.
"He had a bright red face," said McGahee. "He had this evil kind of smile like he was under influence of drugs.
In a seven-month span in 2010, police were called five times because of Loughner's behavior on campus, according to the college.
Then, on Sept. 29, campus police found an Internet video Loughner made in which he calls the college "unconstitutional". He was suspended and told to get a mental health evaluation. He dropped out instead.
Some of Loughner's friends say in the past year that he changed dramatically.
"His attitude sort of went off the deep end," said Bryce Tierney. "He just got sort of really dark."
Loughner volunteered at a local animal shelter and once worked at a sandwich shop. His co-workers also noticed a sudden change.
"He had just moved out of his mom's house, and he was living on his own, and after that he just lost interest in work and everything," Jose Landeros said.
The law enforcement source told Milton that one of the critical questions investigators initially tried to determine is whether Loughner was spurred on by hate groups or pushed or directed by some other individuals or groups. So far there has been no information that is the case.
The source also told Milton that investigators are looking into whether Loughner may have conducted surveillance on Giffords' district office and campaign rallies.
Records show Loughner is a registered independent, Tracy reports. He voted in 2006 and 2008 but not in the midterm elections last November, in which Giffords won a third term, according to the Pima County registrar and the Federal Election Commission.
Giffords' doctors said Tuesday the congresswoman is breathing under her own power and generally "holding her own" in her third day of recovery from a near-fatal gunshot wound. Jared Loughner is being held without bail on federal charges, including one that he attempted to assassinate Giffords.
Loughner's parents are devastated, according to neighbor Wayne Smith, 70.
Smith shocked the Loughners with the news of their son's arrest this weekend as they returned from shopping. He told Tracy the parents can't stop crying.
"They're devastated," said Smith. "How would you feel if your son did it? You'd feel like that you're to blame for the people getting shot. They are just deeply grieved about it."
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Roxanne Osler, of Tucson, whose son had been a friend of Jared Loughner's, said he had a bad relationship with his parents and had distanced himself from family.
"What Jared did was wrong. But people need to know about him," she told The Washington Post. "I wish people would have taken a better notice of him and gotten him help. ... He had nobody, and that's not a nice place to be."