It's unclear what prompted Jared Loughner, accused of embarking on a shooting spree Saturday, to allegedly kill six people and critically wound Rep. Gabrielle Giffords (D-AZ) outside a Tuscon, Ariz., shopping center. "We do not yet have all the answers," said FBI Director Robert Mueller, and trying to discern Loughner's "motivations" would be "premature." Journalists and commentators are less hesitant to speculate about Loughner's mindset, though. (Watch a Fox News report about Lougners motive.) Here are five theories they've floated:

1. Anti-Semitism drove Loughner to shoot
A Department of Homeland Security memo reportedly ties Loughner to the "anti government, anti immigration, anti ZOG (Zionist Occupational Government), anti Semitic" group American Renaissance. "Add that to Gifford's proud status as Arizona's first Jewish U.S. representative, and rumors of anti-Semitic motives boil to the surface," says Cathy Lynn Grossman in USA Today. In another possible clue, "Jewish media quickly spotted that Hitler's Mein Kampf is among the alleged gunman's favorite books."

2. Anti-government paranoia pushed him over the edge
Neighbor and former classmate Michelle Martinez, 22, describes Loughner as an anti-social "conspiracy theorist" who blamed the government for the 9/11 attacks. His "rambling internet postings" are also full of theories associated with the anti-government "Patriot" movement, says Chris McGreal in The Guardian. These include rants against the legitimacy of paper currency instead of gold and silver, disparagement of the post–Civil War "second American constitution," and dark hints that the government uses language and grammar to "enslave" Americans. Giffords just happened to be "the nearest and most obvious representative of 'the government' that Loughner could find," says Mark Potok at the Southern Poverty Law Center.

3. Black magic played a role
A "sinister shrine" found in Loughner's backyard "reveals a chilling occult dimension" to the case, say Matthew Lysiak and Lukas I. Alpert in the New York Daily News. The "alarming altar" features a skull sitting on top of a pot holding shriveled oranges, surrounded by a row of ceremonial candles — all elements used in occult rituals. Was Loughner "driven by other forces" than politics?

4. It was personal
Police found a evidence in Loughner's house that his alleged attempted assassination was "the product of a three-year-old grudge," says Adrian Chen in Gawker. Loughner was "aggravated" after a 2007 meet-and-greet with Giffords, according to former friends and acquaintances. His "brief, weird exchange" with her then — he reportedly asked, "How do you know words mean anything?" and Giffords apparently responded in Spanish before moving on — "may have made an outsized impression on Loughner."

5. Mental illness is the key factor
This "violence will be [best] understood as a result of a severe, untreated or undertreated mental illness," not politics, says Dr. Keith Ablow in Fox News. In fact, "by all accounts, Loughner was psychiatrically ill long before he shot anyone," and should have been placed in a mental ward after his community college expelled him over fears that he would harm somebody. At present, our "shoddy and shattered" mental-health care system has no hope of "dealing effectively with sick individuals like Jared Loughner."