By JACK HEALY Published: July 22, 2012 (SOURCE: NY Times)

With a few keystrokes, the suspect,James E. Holmes, ordered 3,000 rounds of handgun ammunition, 3,000 rounds for an assault rifle and 350 shells for a 12-gauge shotgun — an amount of firepower that costs roughly $3,000 at the online sites — in the four months before the shooting, according to the police. It was pretty much as easy as ordering a book from Amazon.

He also bought bulletproof vests and other tactical gear, and a high-capacity “drum magazine” large enough to hold 100 rounds and capable of firing 50 or 60 rounds per minute — a purchase that would have been restricted under proposed legislation that has been stalled in Washington for more than a year.

Mr. Holmes, a graduate student in neuroscience with a clean criminal record, was able to buy the ammunition without arousing the slightest notice from law enforcement, because the sellers are not required in most cases to report sales to law enforcement officials, even unusually large purchases. And neither Colorado nor federal law required him to submit to a background check or register his growing purchases, gun policy experts said.

A few states like Illinois, Massachusetts and New Jersey, and cities like Los Angeles and Sacramento, have passed restrictions on ammunition sales, requiring permits for buyers or licenses for sellers, or insisting that dealers track their ammunition sales for law enforcement.

But in Colorado, and across much of the United States, the markets for ammunition — online and in storefronts — are largely unregulated, gun-control advocates say.

Law-enforcement officials have refused to say whether Mr. Holmes bought the ammunition from multiple sources or spaced out the purchases over several weeks to avoid drawing attention.

But as investigators combed through the contents of his apartment on Sunday — its explosive booby traps now defused — new details began to emerge of his activities in the weeks leading up to the rampage. They sketch a picture of man once captivated by the science of the human mind growing increasingly interested in weapons and how to use them.

On June 25, Mr. Holmes e-mailed an application to join the Lead Valley Range, prompting the owner, Glenn Rotkovich, to call back, more than once, to invite him to a mandatory orientation meeting. Nobody ever answered, but Mr. Rotkovich described the voice message as nearly incomprehensible.

“It was this very guttural, very heavy bass, deep voice that was rambling incoherently,” Mr. Rotkovich said. “It was bizarre on a good day, freakish on others.”

Mr. Holmes never called back about joining.

In early July, Mr. Holmes ordered a Blackhawk Urban Assault Vest, a knife and two magazine holders from a Web site called Tactical Gear, according to an order slip provided by the company’s chief executive, Chad Weinman. He chose expedited two-day delivery to his apartment in the eastern Denver suburb of Aurora, where the shootings took place early Friday, just a few miles from Mr. Holmes’s apartment.

“I think it conveys a sense of urgency and shows premeditation,” Mr. Weinman said in an interview, adding that the company was “deeply saddened” its gear had apparently been used in a mass killing.

Three weeks after that purchase, stunned and bleeding witnesses outside the Century 16 multiplex in Aurora would describe how a man dressed in a black commando-style outfit and a gas mask strode into the theater where they were watching a midnight screening of “The Dark Knight Rises,” tossed some gas-spewing grenades into the packed auditorium and opened fire.

A law enforcement official who requested anonymity because he was not authorized to speak publicly on the issue said that local investigators in Aurora believed the gunman’s semiautomatic rifle jammed as he was spraying the theater with bullets, forcing him to switch to a slower weapon. Had the gun not jammed, the official said, many more could have died.

The police apprehended Mr. Holmes outside the theater minutes after the shooting, still wearing the body armor. He had four guns with him. A law enforcement official said he also had tablets of Vicodin, a painkiller, in his possession.

¶Chief Daniel Oates of the Aurora police praised the arresting officers on the CBS program “Face the Nation” for noticing that Mr. Holmes’ gear was not quite like that of the other S.W.A.T. officers or he might well have escaped, mistaken for one of the responders.

¶Gun-control groups said the purchases of the ammunition demonstrated how easily anyone could build a veritable arsenal without attracting attention from state or federal law-enforcement officials. Gun groups replied that stricter controls would not make the nation safer, but would only restrict constitutional rights.

¶Only a handful of states and cities have passed any laws requiring that gun dealers keep track of who is buying ammunition.

¶“It’s a wide-open marketplace,” said Tom Mauser, a gun-control advocate in Colorado whose son was killed in the 1999 Columbine shootings. “The Internet has really changed things. You don’t have to show your face. It’s anything goes.”

¶Some top law-enforcement officers were among those calling for more restrictions on ammunition sales.

¶“I have an issue with people being able to buy ammunition and weapons on the Internet,” Commissioner Charles H. Ramsey of the Philadelphia police said on the ABC program “This Week” on Sunday. “I don’t know why people need to have assault weapons. There needs to be reasonable gun control put in place.

¶“And we talk about this constantly, and absolutely nothing happens, because many of our legislators, unfortunately, at the federal level, lack the courage to do anything.”

¶The ammunition and arms Web sites are prolific online. They work like any small hubs of e-commerce, only with warnings to patrons that, under federal laws, they must have clean criminal records and must consult local laws before making their purchases. Buyers can pick up cases of bullets, clips, speed loaders, targets and a wealth of other gear associated with shooting, hunting or target practice.

¶A 1999 bill in Congress aimed at regulating Internet sales of ammunition was never adopted. Democrats in the House and Senate have introduced measures to restrict the sales of large-capacity magazines, but neither measure has gained any traction with the House controlled by Republicans, who tend to be strong supporters of gun rights, and election-year politics shunting politically volatile issues like gun control to the side.

¶“It is a war tool,” Representative Carolyn McCarthy, Democrat of New York, said of the 100-round drum that the police say Mr. Holmes purchased online. “They’re meant to kill. They’re meant to kill as many people in as short a period of time.” Ms. McCarthy’s husband was among six people killed in 1993 by a gunman on a commuter train.

¶But after the Colorado shooting, Democrats and Republicans cast doubt on whether tougher laws could have averted the killing, diminishing the political stomach for any immediate changes in gun laws. Gov. John W. Hickenlooper of Colorado, a Democrat, told CNN’s “State of the Union” that the killer might have built a bomb or found some other lethal device if no assault weapons had been around. And Senator Ron Johnson, Republican of Wisconsin, defended people’s rights to own large-quantity ammunition magazines.

¶“The fact of the matter is, there are magazines, 30-round magazines, that are just common all over the place, and you simply can’t keep these weapons out of the hands of sick, demented individuals that want to do harm,” Mr. Johnson said on “Fox News Sunday.” “And when you try and do it, you restrict our freedoms.”

¶To gun groups, such an unfettered marketplace stands as a bulwark of their Second Amendment rights.

¶Dudley Brown, executive director of Rocky Mountain Gun Owners, said there was no need to track sales of ammunition or require ammunition dealers to follow the same strictures as gun dealerships. He said law-abiding sportsmen and target shooters often bought ammunition in bulk to save money, and may keep rounds on their shelves for years. He said they can easily blow through 400 or 500 rounds in one vigorous day at a shooting range.

¶“I call 6,000 rounds of ammunition running low,” he said.