Jared Lee Loughner, the 22-year-old alleged shooter behind Saturday's deadly rampage in Tucson, appears to have had an obsession with Rep. Gabrielle Giffords. He's now being charged with attempted assassination, among other counts.

Federal officials have filed five criminal charges against Jared Lee Loughner, the alleged shooter behind Saturday’s deadly rampage in Tucson. Loughner faces counts of an attempted assassination of a member of Congress, two counts of murder, and two counts of attempted murder—but FBI Director Robert Mueller says more charges could be on the way under a domestic terrorism statute. Loughner will be arraigned Monday.

A search of Loughner's home turned up disturbing evidence of an obsession with Rep. Gabrielle Giffords, whom he shot in the head at close range on Saturday. Among other items, officials discovered an envelope with the words "I planned ahead," "Giffords," and "My assassination" stored in a safe. According to Caitie Parker, who says she has known Loughner for years, after he met Giffords once in 2007, he described her as "stupid and unintelligent."

Watch Loughner’s alleged YouTube video.

• Gabrielle Giffords, Tea Party Target• Eve Conant: Loughner's Internet TrailLaw enforcement officials have confirmed the gun that was used in the attack was bought legally. The shooter, allegedly Loughner, reportedly fired on Giffords from about four feet away, sending her to the hospital with critical wounds, injuring at least 18 people in total and killing six, including a child and a federal judge. The gun was purchased on November 30 at Sportman’s Warehouse, in Tucson, and was bought along with at least one additional handgun.

While few details about Loughner have been confirmed, some unsettling YouTube videos filmed just weeks ago have been attributed to him. One video consists of a mix between delusional rants and harrowing warnings. After explaining his opposition to what he calls “treasonous laws,” he goes on to write, “In conclusion, reading the second United States Constitution, I can’t trust the current government because of the ramifications: The government is implying mind control and brainwash on the people by controlling grammar.” He continues “No! I won’t pay debt with a currency that’s not backed by gold and silver! No! I won’t trust in God!”

Gallery: Gabrielle Giffords Shooting

In early October, Laughner allegedly posted an eerie video in which he, wearing a trash bag and a hoodie and a giant mask, sets an American flag on fire, with the song “Bodies” by Drowning Pool playing in the background. Loughner, initially reported as a possible veteran, once attempted to enlist but was rejected, according to the U.S. military.

Former classmates remember Loughner as a disturbed, scary presence in the community-college class he attended in early June. Former classmate Lynda Sorenson wrote at the time: “I’m not certain yet if he was on drugs (as one person surmised) or disturbed. He scares me a bit.” Two weeks later, Sorenson described Loughner as “mentally unstable.” He was eventually removed from the class after three or four weeks due to disruptions.

Pictures have also surfaced allegedly showing Loughner volunteering at a book festival, and from his MySpace profile. Loughner listed reading as his favorite interest, and identified a slew of classics as his favorite books, including The Republic, The Odyssey, The Communist Manifesto, and Mein Kampf.

Meanwhile, a second, unnamed person of interest, who had been spotted with Loughner at the scene, has been cleared of involvement after it was determined that he was only Loughner's cab driver.

President Obama has called for a national moment of silence on Monday to commemorate the “the innocent victims of the senseless tragedy.”