While most of a stunned world was still asking "why" after the world's deadliest terrorist attack destroyed New York's World Trade Center, Juan Cole was asking "how?"
What Dr. Cole, a scholar of Middle Eastern history at the University of Michigan, wanted to know wasn't how the airliners were hijacked or the plot concocted. Instead, he wondered how the hijackers had prepared mentally for certain death - and to kill themselves and civilians despite the Koran's injunctions against suicide and murder.
Since the events of 9/11, Cole and other academics have invested many research hours in answering such questions. What they have uncovered has to some degree defied conventional wisdom.
A careful study of the five-page hand-written document - or "doomsday letter" - found in Mohammed Atta's luggage has led Cole and others to conclude that blind rage and fanatical hatred of the values symbolized by the US did not alone motivate the hijackers.
Instead, they may have been manipulated by sophisticated psychological methods involving repetitive readings of selective passages of the Koran along with mesmeric techniques of Islamic mysticism.
On Sept. 27, 2001, the FBI released four of the five pages of text and a translation of the letter found in Atta's suitcase. In the burst of coverage that followed, news media variously dubbed the document a checklist, a manual, a prayer guide, a spiritual exhortation - even a suicide note. Yet the text defied easy classification.
Embedded in the document were subtle clues tantalizing to researchers with a deep knowledge of Arabic and Arab society.
Fluent in Urdu, Farsi, and Arabic, Cole had spent 10 years in the Muslim world. When the FBI posted the document on its website, he immediately logged on.
At first, it seemed an inscrutable list of practical and religious advice. The undercover operatives were directed to review their plans, sharpen their knives, read specific chapters from the Koran, endlessly repeat certain prayers, and be assured of God's pleasure with their actions.
Finally, after months of poring over the document, retranslating and dissecting it word by word, Cole in April presented his analysis on genocide at a Yale University conference in New Haven. (For further analysis, see www.juancole.com).
The letter was much more than a checklist, Cole concluded. It was a mechanism or tool for "autohypnosis" and "psychological manipulation."
Creating and maintaining a noble self-image was a critical function of the document. Suicide was redefined as martyrdom. To craft this self-image of martyrs, the document draws heavily on verses of the Koran pulled out of context, researchers say.
To reinforce this, the document invokes an intricate prayer system apparently borrowed from Sufi mysticism, a narrow branch of Islam, Cole says. But while Sufi mystics used mantra-like repetition to achieve enlightenment, Al Qaeda adapted it for use by the hijackers to induce a mental state free of fear, critical thought, or moral qualms.
One example: A section of the document called the "the last night" contains 15 instructions. In the fifth instruction, the reader is told to pray late into the night repeating certain prayers.
"Praying, chanting, and reciting through the night would aid in the auto-hypnosis necessary to maintaining their self-image as martyrs," Cole writes.
Some academic researchers think Atta must be the author of the document, but others argue that it was more likely penned in committee - or by an Al Qaeda spiritual leader.
Elements of mesmeric manipulation are clearly woven throughout the letter, says Hassan Mneimneh, a Lebanese researcher at Harvard, and a co-author of a detailed analysis of the document.
One reference, for instance, refers to "dhikr," an Arabic term commonly interpreted as "to mention," as it was by the FBI. But it can also mean "to repeat," as in the Sufi practice of mantra-like petition to God.
"In the Sufi context, it is all about getting to be 'alone with the alone' - on your own with God ... even if you're in a crowd," Mr. Mneimneh says.
Not all academics, however, buy into the idea of a brainwashed or hypnotized attacker. Bruce Lincoln, professor of Middle Eastern religions at the University of Chicago, has analyzed the doomsday document but detects no hypnotic system contained in the letter.
Still, he does agree on the document's role as a means of self-justification that systematically and deceptively uses fragmented quotations and excerpts from the Koran plucked out of context to persuade the attackers.
Jerrold Post, a professor of psychology at George Washington University, has not analyzed the doomsday text. But he has delved into the mind-set of suicide terrorists by interviewing dozens of their handlers - those who selected and prepared Palestinian suicide terrorists.
His research has led him to draw a sharp distinction between Palestinian suicide bombers and the 9/11 hijackers, whose psychology "shatters the profile," he says in a phone interview.
The Palestinian bombers are usually young men and women, carefully picked, brainwashed by handlers, and then watched each step of the way until they carry out their mission.
But the 9/11 hijackers were "fully formed, well-educated adults, [and] true believers," Dr. Post says. This enabled them to live among Americans for years without straying from their original convictions and determination.
They remained fixed on their goal, aided, some speculate, by the teaching and routine outlined by the doomsday text.