It was an accessory in the arsenal of Karl Pierson, the student who opened fire last week inside a Colorado high school, leaving one girl in a coma before taking his own life.
"The Anarchist Cookbook," which Pierson read before his rampage, isn't a guide to culinary revolution. It's the original how-to of homicide and mass murder - and sales are still raging, with distribution from the likes of Amazon and Barnes & Noble, even as the work is linked to terrorist acts around the world.
Now, in rare interviews with NBC News, the publisher and the author of the "Cookbook" are trading blows about the book's future.
"'The Anarchist Cookbook' should go quietly and immediately out of print," says William Powell, who wrote the book as a stern 19-year-old, an opponent of the Vietnam War who felt violence was justified if it could prevent even greater violence in the process. He has since renounced that position, but never so forcefully, telling NBC in an email that "it is no longer responsible or defensible to keep it in print."
Published in 1971, the book has sold more than two million copies and influenced hundreds of malcontents, mischief makers, and killers. Police have linked it to the Croatian radicals who bombed Grand Central Terminal and hijacked a TWA flight in 1976; the Puerto Rican separatists who bombed FBI headquarters in 1981; Thomas Spinks, who led a group that bombed 10 abortion clinics in the 1980s; Timothy McVeigh, who bombed the Alfred P. Murrah Federal Building in Oklahoma City in 1995; the Columbine High School shooters of 1999; and the 2005 London public transport bombers.
Just in the last two years, law enforcement has tied the volume to Arizona shooter Jared Loughner, the Boston Marathon bombers, and at least a half dozen alleged terrorists and school shooters.
Powell, meanwhile, has apologized for the destructive cultural force that bears his name, and posted an eight-paragraph warning to would-be buyers on the book's Amazon page. But Powell has no say: the rights belong to the publisher and always have - and the publisher has never wavered in his commitment to selling.
"You know, we don't ban books in America," says Billy Blann, who bought the rights to the "Cookbook" in 2002, just as digital sales took off.
Blann is the founder of Delta Press, "the world's most outrageous catalog," as he calls it, and the purveyor of guides on "Justifiable Homicide," "The Poor Man's Nuclear Bomb," and "The Butane Lighter Hand Grenade."
Of hundreds of titles offering frank tips on bombs, bullets and blades, however, "The Anarchist Cookbook" remains his most-asked-for volume, he says, contributing largely to his $3 million in annual revenue and supporting a semi-retired life in a 6,000 square foot home in southern Arkansas.
"I'm sure I got my money back," he says of the deal.
Web searches for the "Cookbook" have grown "more than 5,000 percent" in the last decade, according to an estimate by Google Trends.
At the same time sales of the book have surged past the Penguin and Signet editions of Moby Dick, according to Amazon rankings, and Blann has no plans to pull back now.
When told of this latest school shooting, he goes silent a moment on the phone. "I feel bad about that," he says at last. "But there's victims of almost anything and everything, and I just don't think we need to start banning books in America."
This isn't Blann's first public fight over violent literature. A little more than a decade ago, a former police chief and several preachers in his hometown of El Dorado, where he serves on the city council, tried to shutter Delta Press, calling it a "satanic stronghold" and a cesspool for violence and subversion.
"God showed me the city of El Dorado," said Dwain Miller, a pastor at Second Baptist Church, waving a copy of the Delta Press catalog, "and he said, 'there is a dark cloud over the city.'" Blann said his books were for "entertainment" and "academic" use only, a line he echoes today.
But what about Amazon and Barnes & Noble? Neither bookseller responded to NBC's requests for comment. Both companies show the "Cookbook" in stock and ready to ship in time for Christmas. Both will even gift-wrap it, and ship some of Blann's other titles - including primers on how to garrote, stab, and burn - in the same bundle for free.
Legally, this is all protected, says Christina Wells, a First Amendment scholar at the University of Missouri Law School. As public expression, a book can only be prohibited or punished if it "is likely to incite imminent lawless action," according to a 1969 Supreme Court ruling.
It's hard to prove that an act was aided or abetted by a given book, or that the influence was imminent, so there's never been a successful lawsuit against "The Anarchist Cookbook"-or any how-to guide to violence for that matter. Corporate booksellers have escaped legal action as well. "Their First Amendment defense is pretty strong," says Wells.
In 2010, after a father-son team of British white supremacists drew on "The Anarchist Cookbook" to make a jar of ricin, a London judge joined police in calling for a ban on the title. But Amazon said the law could not compel them to stop selling the book. "Our goal is to support freedom of expression and to provide customers with the broadest selection possible so they can find, discover and buy any title," a spokesperson for the bookseller said at the time, adding that they would only remove a book if the law specifically found it to be illegal.
On Monday the parents of Colorado school gunman Karl Pierson said they were "shattered" by their son's actions. They don't understand why he made three Molotov cocktails, grabbed a shotgun and a machete, and slipped into a side door of his high school, gun drawn. Perhaps the "Cookbook" wasn't pivotal, although machetes and Molotov cocktails are included. It's a mystery and a tragedy for everyone.
But for William Powell, it's also an opportunity, a chance to make the two chapters of his life into one. In the 40-plus years since he wrote "The Anarchist Cookbook," he has reinvented himself as an educator on the international stage, running a series of elite schools abroad, before settling in Malaysia. There he owns a teacher training center and writes books on pedagogy for the State Department.
One of his fundamental ideas is that schools need to be made safer, and, ironically, a way to move toward that goal is to pull "The Anarchist Cookbook" out of print.
"I hope this helps," he says.
NBC News' Polly DeFrank contributed to this report.
Tony Dokoupil, Senior Staff Writer, NBC News