What kind of person would put cyanide in bottles of Tylenol capsules?

Psychiatrists hesitate to guess, saying every case of innocent, unwitting people being killed or injured is different. Many past incidents seem similar on the surface: the razor blades or poison found in Halloween apples, needles found in supermarket hot dogs, acid in eyewash bottles, the imported oranges tainted with poison in Europe in 1978.

There are also surface similarities with mass shootings by snipers of passers-by, or with terrorist efforts to poison water reservoirs, or with extortion threats to poison supermarket food. All seem directed at anonymous victims unknown to the killer.

But the cases are very different and so relatively rare that no generalizations are possible, the experts say. In fact, they don't fit any known pattern of craziness.

"I don't know of any specific syndrome of mental illness that this kind of behavior is associated with," said Dr. Loren Roth, forensic psychiatrist at the University of Pittsburgh Medical School's Law and Psychiatry Center.

Most mentally ill people, he said, "can't get things together. Acts like this suggest organized behavior." Unlike snipers or "Jack the Ripper" mass murderers, the Tylenol killer is probably a coward who doesn't want any personal contact with victims.

"One kind of saboteur is disgruntled, doesn't have any other outlets for expressing rage and yet doesn't have the sadistic cruelty that makes him or her want to watch someone suffer directly," said Dr. Frank M. Ochberg, a psychiatrist and medical director of the St. Lawrence Hospital in Lansing, Mich.

Convicted mass murderers have tended to be psychotic, hearing voices or otherwise being out of contact with reality, with occasional periods of uncontrollable rage, said Conrad Hassel of the FBI's behavioral science and counterterrorism unit. "But usually these are people who get involved personally in the murder. This guy is doing it at a distance," he said.

Like an arsonist who stands in the crowd to watch the building burn, "The poisoner can get a sense of nationwide gratification anonymously, vicariously without having to face his or her crimes, using television to terrorize the nation," said Dr. Robert Kupperman, executive director of the Georgetown Center for Strategic International Studies.

Another kind of killer "would understand the whole catastrophe, acting in a cool, deliberate way in a form of sabotage," trying to hurt an employer, a company, an industry or even a political enemy by killing innocent people, Ochberg said. The Tylenol poisoning case, he continued, clearly involves someone with technical sophistication on how to introduce the poison, access to stores of it and a great deal of patience.

A Palestinian terrorist group claimed in 1978 to have put poisonous mercury injections in Israeli oranges, the country's chief foreign exchange earner. This and similar criminal acts involved announcements that the deed had been done.

There was no announcement in the Chicago area. Some other unannounced efforts at mass killing have involved poison introduced into water supplies and bombs left in crowded places, Hassel said. "These often turn out to be Ph.D. types with a grudge against the world . . . . They understand the difference between right and wrong but only intellectually, with no moral sense, no conscience. They just carry out their fantasies."

Even the people who booby-trap Halloween treats are different from the Tylenol murderer, Ochberg said, because they have a specific target in mind. "They're the kind that get pleasure out of hurting children. They become the witches and goblins," he said.

All the experts worried that analyzing the case would put ideas into other sick minds. Several refused to talk about it for that reason. "I deplore the sensationalism of speculating about it," said one Washington forensic medical expert who did not want his name used. "All you can say is that it's someone pretty emotionally disturbed." graphics /photo: AP A bottle of a tainted Tylenol batch.