The Rajneeshees, who ran a commune in central Oregon in the 1980s, did not fit the popular image of would-be terrorists.
Most followers of Bhagwan Shree Rajneesh were not wild-eyed fanatics, but middle-class lawyers, doctors, accountants, teachers and other well-educated people who seemed normal enough.
Americans were shocked to learn in 1985 that this outpost of transplanted suburbanites was a launching pad for the first large-scale biological attack in U.S. history: the poisoning of 751 people in The Dalles, Ore., with restaurant food sprinkled with salmonella germs grown in a commune laboratory.
But cult psychology experts say such an incident should come as no great surprise to anyone. It merely underscores the fact that seemingly normal, well-educated people can be persuaded to commit unthinkable crimes, including flying airliners into skyscrapers.
"There are many similarities between the way people are programmed in cults and in terror groups that can result in an act of suicide bombing," says Steve Hassan, a former member of the Rev. Sun Myung Moon's Unification Church.
Hassan has counseled ex-cult members in Florida for 20 years and says many, including himself, would have been "ready to die for the cause if necessary."
That certainly was the case with the 19 hijackers involved in the Sept. 11 terror attacks.
Contrary to what the public may believe, cult experts say, the suicide pilots were probably neither crazy nor motivated, except in a superficial sense, by hatred for the United States.
The chilling and mundane likelihood, they say, is that someone talked the attackers into it over an extended period of time, using techniques that every former cult member and deprogrammer would recognize.
"What I find so astonishing is that most people don't realize how influenceable all humans are," says Margaret Singer, an emeritus professor of psychology at the University of California at Berkeley.
Singer's interviews of nearly 6,000 former cult members have convinced her that groups as dissimilar as the hippie-style Rajneeshees and the suicidal People's Temple recruit and control members in much the same way, despite vast differences in ideology.
"They're all extended con games," Singer says, "whether it's a cult or a terrorist organization."
In 1994 and 1995, Japan's Aum Shinri Kyo doomsday cult killed 19 people and injured more than 5,500 in two nerve-gas attacks in Matsumoto and Tokyo.
In the Tokyo attack, 10 cult members simultaneously boarded subway trains in five locations with containers of deadly sarin -- a coordinated effort at mass murder not unlike the Sept. 11 attacks in the United States.
Dr. Steven DuBrow-Eichel, a Philadelphia psychiatrist who specializes in cults, thinks the Qaeda terrorist group, chief suspect in the Sept. 11 hijackings, most closely resembles Aum Shinri Kyo.
"Their apocalyptic vision is similar in many ways," he says, "and their methods are very similar."
In his view, al Qaeda and Aum Shinri Kyo are almost indistinguishable in their adulation of a single charismatic leader -- Osama bin Laden for al Qaeda, Shoko Asahara for the Japanese group -- and in their sincere conviction that God sent them to purify the world.
Al Qaeda's chosen enemies -- chiefly the United States -- are equated with disease and therefore in need of cleansing. It is almost, says DuBrow-Eichel, like being attacked by fanatical hygienists.
By accepting that the cult is good and anyone who disagrees with it is evil, there can be no guilt in killing those who disagree.
People who have treated former cult followers are not surprised at the profiles of the suspected suicide pilots of Sept. 11. They were very much like the middle-class recruits of the Rajneeshees and Aum Shinri Kyo.
Mohamed Atta, the suspected leader of the suicide bombers, has been described in news reports as a shy, considerate son of a lawyer and very bright.
He grew up in a religious home and studied architecture at the University of Cairo. He joined an Islamic militant society, sympathizing with insurgents who blamed Egypt's secular government for extremes of wealth and poverty.
While living in Hamburg, Germany, Atta made lengthy trips to the Middle East. He returned from one visit, friends thought to Afghanistan, with a new beard and a new personality. The new Atta didn't smile and, one friend recalled, refused to shake hands with a woman.
After Atta was identified as the suspected pilot of American Airlines Flight 11, the first to crash into the World Trade Center, his bewildered father told reporters it must have been someone else. He insisted that someone must have stolen his son's identity.
The father's disbelief, therapists say, is a familiar one. They can recount hundreds of stories about people undergoing personality changes so radical their families scarcely know them.
Cults offer instant acceptance and use a variety of tactics to indoctrinate new members. They hear and see only what the cult leaders approve.
Communication with the outside is cut off. To reinforce the member's group identity, a new name and distinctive clothing may be provided.
The group's goals become paramount. Good and bad are defined in terms of doing the leaders' bidding.
The general theme is that members of the cult are a chosen few who will reap a great reward.
Depending on the cult, it may be guaranteed entry to heaven, survival of Armageddon or a reserved seat on a UFO.
"It's an us-against-them mentality," Singer says. "The cult members or the terrorists are the elite, and all the rest of the world is unworthy of life."