A computer, cellphone, homemade explosives and Batman mask all seized at the Colorado apartment of James Holmes could help shed light on the mind, motive and modus operandi of the suspected mass killer, a federal law enforcement official said Sunday.
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The official, who asked not to be identified because he is not authorized to comment publicly, said the computer could aid the effort to determine how long the suspect had been allegedly planning the attack and other details of the massacre.
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A maze of incendiary devices arrayed inside Holmes' apartment included 10 gallons of gasoline that was likely intended to serve as an accelerant to any fire caused by an explosion inside, the official said.
The devices included about 30 aerial shells commonly used in commercial fireworks displays.
The official said the shells had been cannibalized, reconstructed and set up in the living room, where a stream of wires connected them to a "control box" in the unit's kitchen. The box was disabled Saturday by bomb technicians using robotic devices and a controlled detonating device.
Also Sunday, the University of Colorado said it is helping authorities determine whether Holmes used his position as a graduate student to order materials for the potentially deadly booby traps.
Police said Holmes received deliveries over four months to his Aurora, Colo., apartment and the school. They haven't identified the contents. University spokeswoman Jacque Montgomery said the school is looking into those packages received at the school.
The latest information represents more pieces to a puzzle authorities are constructing to determine what was happening inside the mind of the quiet, intellectually gifted neuroscience student suspected of morphing into a vicious killer.
Aurora Police Chief Dan Oates says Holmes, 24, has "lawyered up" and is not talking.
Was this killer mentally ill?
"It says a lot about the type of prejudice we have when we automatically go to the presumption that a clinical mental illness was the cause," says Praveen Kambam, a professor of psychiatry at the University of California-Los Angeles. "Even the surgeon general of the United States has said there's very little risk of violence or harm from a stranger who has a mental disorder.
"Not all bad behavior comes from mental illness. Sometimes it can simply be bad behavior."
In a résumé posted on Monster.com, Holmes listed himself as an "aspiring scientist" and said he was looking for a job as a laboratory technician.
The résumé, first obtained by The Press-Enterprise in Riverside, paints a picture of a brilliant young man brimming with potential: He worked as a summer intern at the Salk Institute for Biological Studies in La Jolla in 2006 and mapped the neurons of zebra finches and studied the flight muscles of hummingbirds while an undergraduate at the University of California-Riverside.
He also worked as a summer camp counselor to underprivileged children at a Jewish camp in Los Angeles in 2008.
In Rancho Peñasquitos, a community of picturesque hacienda-style homes surrounded by hills and canyons outside San Diego where Holmes grew up, residents have a hard time squaring the quiet teen who didn't call attention to himself with the violent image of Holmes emerging now.
Those who knew Holmes in the upscale San Diego community remember a polite young man who kept to himself and excelled academically.
"He was really talented, really smart," said Porsche Parkman, 19, who attended Westview High School with Holmes' younger sister, Chris. Holmes graduated from the school in 2006. "He was so nice and his family was always there for him. Nothing seemed wrong."
Her description of the young man seen with a ready smile in his high school yearbook photo stands in stark contrast to the 6-foot-tall gunman dressed in head-to-toe black body armor whom police say opened fire with multiple weapons in a crowded suburban Denver movie theater, killing 12 people and wounding 58.
Today, Aurora police portray Holmes as a suspect intent on killing, taking the violence even further by booby-trapping his apartment to kill the first person to enter, most likely a police officer.
"This apartment was designed to kill," Oates said. He said Holmes had a "high volume" of deliveries of materials and ammunition that could explain the aerial shells, trip wires and other explosive devices found in his apartment.
"What we're seeing here is some evidence, I think, of calculation and deliberation," Oates said Saturday. "If you think we are angry, we sure as hell are angry."
In the six months before the shooting, police said Holmes bought at least 6,000 rounds of ammunition, an AR 15 assault rifle, a Remington shotgun and two 40-caliber Glock handguns. He bought them legally, according to a federal law enforcement official who was not authorized to speak publicly.
Oates said Holmes used a rifle, shotgun and one of the handguns during the attack.
At the same time that authorities say he was buying ammunition and weapons, Holmes was in the process of dropping out of the University of Colorado's graduate neuroscience program in Aurora. He had joined the program a year ago, but by June he had withdrawn, the university said in a statement.
Dan Meyers, spokesman for the University of Colorado School of Medicine, would not say why Holmes left.
Oates said the FBI Behavioral Analysis Unit is working with local police to try to determine a motive for the shooting.
Holmes seems to have little online presence. Unlike many people his age, he does not have accounts on Twitter, Facebook or other social media.
University of Colorado biology student Kaitlyn Fonzi, who was living below Holmes in a student-housing complex in northern Aurora, had seen Holmes in the building several times and remembers a student who looked like any other on the medical and academic campus across the street from their apartment building.
"You never really think anything like this is going to happen," Fonzi said after the building was evacuated when police tried to defuse the trip wires they said Holmes set up.
In Rancho Peñasquitos, the suspect's family still lives in the two-story white house with a red-tiled roof where he grew up.
Holmes, who graduated with high honors with a bachelor of science degree in neuroscience from the University of California-Riverside, was raised in a math and science household. His mother, Arlene, has been licensed as a registered nurse for more than 30 years. His father, Robert, is a mathematician who develops statistical models for financial services, specifically looking at fraud.
Theirs is a community where neighbors are friendly and know each other, said one neighbor, Rose To.
"We know the parents as good neighbors," said To, whose home is across the street. "We watch out for each other here."
Lindsay Van Leeuwen, 32, lives three doors away from the Holmes' family. She has lived there four years and said she was probably one of the newest residents in the neighborhood. She doesn't know the family well, she said, but she received a card from them when her twins were born two months ago.
"It's scary. I'm shocked that it's happened right down the street," Van Leeuwen said.
Parkman and her husband, William, 19, remember a friendly family who kept to themselves but were supportive one another.
She became friends with Holmes' sister during their freshman year at Westview, about 3 miles from where the Holmes family lived.
"Her dad was really smart. Their mom was nice, quiet. They let (their children) be who they were," Porsche Parkman said.
William Parkman marveled at how Holmes had gone from a proud example of a successful graduate of their high school to one of the most hated people in the country.
"The news reports you hear about him, it's as if people are talking about one person in San Diego and one in Colorado," he said. "Who he is now is not who he was in San Diego."
On Sunday, ABC News aired a video showing Holmes as a shy, thin teen speaking at a science camp at Miramar College in San Diego when he was 18.
His presentation is on "temporal illusion," which he defines as "an illusion that allows you to change the past."
A woman who introduces Holmes in the video says he wants to become a researcher and make scientific discoveries.
She says his dream is to own a Slurpee machine, eliciting laughter from the audience and a smile from Holmes.