A possible link between Jared Lee Loughner, the primary suspect in the shooting of Rep. Gabrielle Giffords, and American Renaissance, the publication of an anti-immigration group, offers potential new insights into what may have caused the 22-year-old Arizonan to carry out the attack, which killed six people and wounded more than a dozen outside a Tucson, Ariz. stripmall on Saturday.

The shooting attack gravely wounded Representative Giffords and killed her aide Gabriel Zimmerman, US District Judge John Roll, a nine-year-old girl, and three others. The hail of gunfire shocked the nation and reinvigorated scrutiny of rancor and anger-fueled debate in American politics.

On Sunday, Fox News quoted a Department of Homeland Security memo that states Mr. Loughner is "possibly linked" to American Renaissance, which DHS says promotes views that are "anti-government, anti-immigration, anti-ZOG [Zionist Occupational Government], anti-Semitic." Both Giffords and Mr. Zimmerman are Jewish.

American Renaissance is the publication of the The New Century Foundation, described by the Anti-Defamation League as a "self-styled think tank." The ADL, on its website, calls American Renaissance a "white supremacist journal and companion Website" that "promotes pseudoscientific studies that attempt to demonstrate the intellectual and cultural superiority of whites and publishes articles on the supposed decline of American society because of integrationist social policies."

The DHS memo quoted on Fox goes on to say: "Arizona Rep. Gabrielle Giffords, the target of Loughner’s firing frenzy, is the first Jewish female elected to such a high position in the US government. She was also opposite this group’s ideology when it came to immigration debate."

"When you look at Loughner's web posts, he puts himself out as half fantasy seeker and dreamer and half political philosopher, and American Renaissance, while a hate group, markets itself as a political philosophy organization," says Brian Levin, director of the Center for the Study of Hate and Extremism at California State University, at San Bernardino.

Mark Pitcavage, director of investigative research at the Anti-Defamation League, is skeptical about any hard connection between Loughner and American Renaissance.

"The fans of American Renaissance tend to be older and they tend to be intellectuals or pseudo-intellectuals," says Mr. Pitcavage. "Based on the limited nature of [Loughner's] internet footprint suggesting his thoughts and beliefs, there's nothing to lead one to think he would lean that way. It's perplexing to us that there is a notion of a substantial connection."

In Arizona, particularly, immigration issues, including the passage of a tough anti-immigration law last year, overlapped with parts of the broader tea party agenda. Giffords narrowly defeated a tea party candidate in November's election. She supported the federal health-care reform law and spoke out against Arizona's tough anti-immigration law, both counter to her tea party opponent. American Renaissance's website carries what appears to be a paid tea party advertisement featuring the "Don't Tread on Me" flag that's become synonymous with many of the movement's protests.

After the shooting, Pima County Sheriff Clarence Dupnik, a Democrat in a largely Republican state, condemned "the vitriol that comes out of certain mouths about tearing down the government." But the potential link to American Renaissance frames the shooting in a different, and possibly more complex, light.

The New Century Foundation was founded by Yale University graduate Jared Taylor, the author of several books on race and policy who has has written that diversity is "dangerous" because it is "one of the most divisive forces on the planet."

Mr. Taylor has become a well-known and oftentimes mainstream commentator on race and immigration issues, having appeared on networks like CNN as well as hard-right radio shows. The ADL describes his bailiwick as "intellectualized white supremacy."

Invited by a college conservative group to speak at Clemson in 2007, Taylor said, “It is a mistake to assume it is wrong to prefer the company of people similar to oneself. ... It is universal, and I think there’s every reason to believe there are innate biological reasons. … In [the] United States, this kind of preference … is recognized and encouraged and institutionalized so long as the people who are expressing this preference are not white.”

Fox News quoted Taylor Sunday as calling the DHS' views "scurrilous." He took especial issue with the reference to his group being "anti-ZOG."

"That is complete nonsense," he told Fox. "I have absolutely no idea what DHS is talking about. We have never used the term 'ZOG.' We have never thought in those terms. If this is the level of research we are getting from DHS, then Heaven help us."

Taylor said he checked his organization's records going back twenty years and Loughner never subscribed to American Renaissance's publications.

Through web posts and interviews with those who know him, a picture of Loughner has emerged as an anti-social, erratic and possibly mentally unstable young man, whose anti-religion and anti-flag views run starkly counter to the broader tea party platform. Caitie Parker, one of his high school classmates, says in press reports that in the past Loughner was "quite liberal," and a "political radical." Sheriff Dupnik said Saturday, "He has a troubled past, I can tell you that."

Among favorite books listed on Loughner's MySpace page are "Brave New World" by Aldous Huxley and Hitler's "Mein Kampf."

In his internet posts, Loughner complains that the government was in some way trying to take advantage of him. "I know who's listening: Government officials, and the People," Loughner wrote. "Nearly all the people, who don't know this accurate information of a new currency, aren't aware of mind control and brainwash methods. If I have my civil rights, then this message wouldn't have happen."

Some commentators minimized the likelihood Loughner was politically motivated.

"For all the instant analysis that this might be tied to political attacks on Giffords and others who supported President Obama on health-care reform, there's not a whiff of politics in Loughner's language about coins and calendars and other ramblings," writes USA Today's Cathy Lynn Grossman. "Yet he does exclaim in his YouTube video, 'No! I won't trust in God!'"

Trying to tease out definitive links between Loughner and specific political movements or groups is problematic, says Mr. Levin, of California State University.

"Extremists can be like bullets ricocheting off the political spectrum and bouncing to whatever gives them comfort or meshes with their paranoid distrust," he says.

But Levin adds that notably rancorous politics, tied to deepening distrust of government, can play a supporting role in fueling a violent attack like the one unleashed Saturday.

While expressing her condolensces to Giffords and the victims, former Alaska Gov. Sarah Palin removed from her website a controversial graphic from last year that showed crosshairs on 20 districts being targeted by Republicans, one of which was Giffords' seat. Liberals, including President Obama, have also used rhetoric – as well as maps with shooting targets – that could also be seen as exhorting violence.

"When we have people who are irresponsibly exploiting the political debate, one of the side effects is it's going to resonate with really unstable people who are looking for a philosophical overlay to legitimize their irrational aggression," says Levin. "What happens is they create a quasi-political philosophy that justifies their anger, so you can't necessarily pin that on one party or another."