Twenty-three-year old Seung-hui Cho mailed a tape to NBC News before he killed 30 students at Virginia Tech four years ago.
"You have vandalized my heart, ripped my soul and torched my conscience," said Cho on the tape. "You thought it was one pathetic boy's life you were extinguishing. Thanks to you, I died like Jesus Christ to inspire generations of the weak and the defenseless people."
Brad Garrett says that Cho was able to go from room to room methodically shooting people, without changing expression, "because he's not shooting human beings, he's shooting things that have caused him pain and anger. He's going to seek revenge on them, and it's okay if you're dead because you don't count."
Law enforcement professionals and psychiatrists say another classic lone wolf trait involves sexual dysfunction.
George Sodini, 48, killed four women at a Pittsburgh health club after months of rejection by women he asked on dates.
"It is easy for me to hide from my emotions for one more day," said Sodini in a video posted on YouTube.
In Washington, D.C.,the great fear among law enforcement is of copycat lone wolves who may target other unguarded members of Congress.
But law enforcement officials say spotting a lone wolf before he can kill is highly unlikely.
Brad Garrett questions what can really be done to stop lone wolf attacks. "If you're talking about thousands and thousands of people out there," said Garrett, "it's a scary thought.
Garrett said lone wolves pose as great a danger as organized terrorists. "Maybe even more so," said Garrett, "because they're here, they're in our community. Maybe a few people see them acting inappropriately, but they're just doing their thing slowly and one day they erupt."
The suspect in Arizona was easily and legally able to buy his weapon at a gun store outside Tucson. Every country has unstable people, but not every country has such liberal gun laws.
Daniel Webster, codirector of the Johns Hopkins Center for Gun Policy and Research, told ABC News that controlling the supply of guns is key. "In order to lower the number of shootings and lethal shootings," said Webster, "whether they're mass shootings or not, you have to do something to address the availability of guns.
But Welner said that in his professional opinion, the easy availability of weapons did not play a role in the Tucson incident.
Welner says the real answer is to focus more on the heroes of the shooting, such as Congresswoman Gifford's intern Daniel Hernandez, who was recognized today in the Arizona legislature, and focus less on those responsible for the pain.
"It's an attention seeking crime," says Welner, "which is why the perpetrators of mass shootings should be remembered as rejects, losers, perverts, because then there won't be copies."
Said Welner, "That is a key message not just for the press. [It's] a message for teachers, it's a message for neighborhoods, and it's how we as a society can eliminate something that's distinctively American. "