It had happened it before–all too many times before:

• Midnight vigils for the victims of yet another spree-killer.

• Makeshift memorials of flowers, candles and teddy bears.
• Grief counselors for students at elementary, junior high and high schools.
• And, of course, the inevitable question: “Why?”

And Americans had seen it all before–-too many times before:

• After the San Ysidro McDonald’s shootings, 1984: 21 dead, 19 wounded.
• After the 101 California Street shootings in San Francisco, 1993: 9 dead, 6 injured.
• After the Columbine High School shootings in Colorado, 1999: 15 dead, 21 wounded.
• After the Virginia Tech shootings, 2007: 32 dead, 23 wounded.
• After the Tucson shootings, 2011: 6 dead, 13 wounded.

And then, on July 20, 2012, came the massacre at the Century 16 Theater in Aurora, Colorado: 12 dead, 58 wounded.

People who wanted nothing more than to see a movie they were eagerly anticipating: The latest addition to the hugely popular “Batman” franchise: The Dark Knight Rises.

The scene of the crime: The Century 16 Theater in Aurora, Colorado

Snuggled into their seats, some eating popcorn or candy, others sipping sodas. None of them expecting that the violence on the screen would suddenly consume them in real-life.

It was a scene of which nightmares are made:

• A sudden eruption of smoke and fire as a tear-gas canister explodes.
• A lone gunman–brandishing a Smith & Wesson AR-15 semi-automatic rifle, a 12-gauge Remington Model 870 shotgun, and a G23 .40 caliber Smith & Wesson Glock pistol.
• First he blasts the ceiling with a shotgun, and then opens fire on the audience, stopping only to reload his weapon.
• He begins aiming at the back of the room, and then targets people who are scrambling to escape in the aisles.
• Some bullets penetrate the wall of the cinema and injure people in an adjoining theater, where the same film is being screened.
• Adding to the nightmarish quality of the scene: The appearance of the gunman–dressed all in black: a ballistic helment, vestand leggings; a throat protector; a groin protector; a gas mask; and black tactical gloves.

As terrible as the massacre was, it could have been worse.

Police arrived in about 90 seconds and arrested the shooter, James Holmes, in the parking lot of the Century 16 Theater he had just ravaged.

Still, the statistics were terrible enough:

• Twelve people–several of them heroes who died shielding others with their bodies–would never return to those who loved them.
• Of the 58 wounded, an unknown number would be physically scarred for life.
• Some would never fully recover from their injuries.
• They would not be able to walk. Or see. Or use their arms or hands.
• Almost all those who were in that theater–-even those who escaped without a scratch-–would be emotionally tormented for months or years to come.
• Some would never escape those moments of murderous insanity.

It’s possible that Holmes, then 24, an honors graduate of the University of California Riverside, became that most lethal specimen: The genius who slides into madness.

James Holmes

Holmes moved to the University of  Colorado School of Medicine in Aurora in May, 2011, to pursue a PhD in neuroscience.

He had always excelled in his studies, but in early 2012, his grades took a sharp decline. In June, he told the college that he was going to drop out.

Meanwhile, he was amassing an arsenal of weapons and ammunition.

He bought two Glock pistols, a semi-automatic rifle and a shotgun over the last two months from local gun stores and 6,000 rounds of ammunition via the Internet–-all purchased legally under state law.

In early July, 2012, Holmes ordered the paramilitary bulletproof clothing and gas mask that he intended to wear on his rampage.

Finally, he dyed his hair a shocking red-orange and rigged his university apartment with trip-wires and homemade booby-traps. When he was arrested, he told police: “I am the Joker.”

Commentators immediately began asking: Why did Holmes choose to snuff out the lives and dreams of so many people?

But a better question is: “How did he do it?”

It may never be finally known why he did it. But the answer to how makes clear a fundamental truth:

He could not have done it without access to the awesome firepower he was legally able to purchase:

• The AR-15 semi-automatic rifle is designed for easy reloading. “Even without the grand-sized mag[azine]s, many people who are practiced can reload in 1½ to 2 seconds,” said Steven Howard, a Michigan attorney and security and firearms expert.

• The AR-15 is a weapon of war.  Its only purpose is to kill large numbers of people–quickly.  Its 100-round drum magazine  allowed Holmes to five 50 to 60 rounds within one minute.
• The Glock pistol uses a 15-round clip. When it’s done the shooter simply ejects the empty clip and slams in another one, and he’s ready for more killing.

And who has made all of this mayhem not only possible but politically invincible?

Who ultimately bears responsibility not only for those murdered and maimed at an Aurora theater but for the almost 100,000 people who are killed or wounded every year from gun violence?

Your friends at the National Rifle Association.