At the beginning of the bloody and seemingly quixotic trail of the Unabomber stands a man with a question:

"If you've been involved in something like this, you really want to know why," said Buckley Crist, the Northwestern University material science professor whose name appeared on the return address of the first bomb attributed to the Unabomber. The bomb slightly injured the security officer who opened it in 1978.

It is the same question asked by John Hauser, whose dreams of becoming an astronaut ended in 1985 with a Unabomber blast that threw his Air Force Academy ring into a wall so hard its lettering made a legible impression.

Diogenes Angelakos asks it, too. He tied a makeshift tourniquet around Hauser's arm moments after the blast. Angelakos' own right hand had been injured by another of the Unabomber's packages less than three years before.

There were few answers Thursday for these survivors of the Unabomber's nearly 18-year campaign of violence--and the families of those who died--as Unabomber suspect Theodore Kaczynski was arraigned in a Montana courtroom on a felony charge of possessing bomb components.

That left the victims to pick through the details of their lives in search of threads, however frayed, that might somehow connect them to Kaczynski, the brilliant mathematician, mountain man and mysterious figure the FBI believes killed three people and injured almost two dozen.

Only one target, Vanderbilt University computer science professor Patrick Fischer, believes he may have crossed paths with Kaczynski, and that was in a college math class more than 30 years ago.

Others say they are relieved that the years of vague unease, of carefully scrutinizing their mail and peering suspiciously at strangers, finally may be over. Still, they are puzzled.

"I've thought about it a lot but I still don't know why it happened," said Percy Wood, the former president of United Airlines, who was injured June 10, 1980, in the fourth explosion attributed to the Unabomber. "I've never heard the guy's name. I never saw him before."

Wood, who is 75 and lives in Florida, suffered burns and cuts over much of his body when he opened a package left in the mailbox of his Lake Forest home. The bomb was rigged inside a book, "Ice Brothers," about the crew of a Coast Guard vessel off Greenland in World War II.

The Unabomber is believed to be fascinated with wood, sometimes encasing his bombs in wood, and may have chosen Wood in part for his name.It was among the oddest of the Unabomber's 19 attacks, littered with the seductive and obscure clues that would lead authorities down hundreds of dead ends before they took Kaczynski into custody Wednesday at his Lincoln, Mont., cabin.

Last month, as the FBI closed in on Kaczynski, they revisited at least four of the Unabomber's targets to show them color photographs of several men, including the 53-year-old loner who was raised in southwest suburban Evergreen Park.

Fischer, the head of Vanderbilt University's computer sciences department, didn't recognize Kaczynski but became curious when agents gave him a brief biography of the man.

Both men studied mathematics in Cambridge, Mass., in the early 1960s. Fischer, who was a graduate student at the Massachusetts Institute of Technology, took a course called "Computational Linguistics" at Harvard University in 1962, the same year Kaczynski got his math degree from Harvard.

"It's conceivable that we took a course together, but I don't know for sure," said Fischer, who is 62. "We could have overlapped as students. I don't remember the name or the face."

Also, Fischer's father, Carl Fischer, taught mathematics at the University of Michigan in Ann Arbor and shared an office with Cecil J. Nesbitt, a Michigan professor who read Kaczynski's doctoral thesis and recommended him for a departmental award.

Patrick Fischer was giving a series of lectures in Puerto Rico when a package addressed to him arrived at his Nashville office on May 5, 1982. Fragments from the pipe bomb hidden inside cut his secretary, Janet Smith, as she opened it, but she recovered from her injuries.

For several years, Fischer and his family went into "defensive mode." They always locked the doors and screened their mail but eventually learned to live with the persistent fear that the Unabomber might attack again.

"I was cautious but I was never paranoid," Fischer said. "It's great if they finally got this guy, and they get a conviction. He's basically a serial killer."

The first person killed by the Unabomber was 38-year-old Hugh Scrutton, a Sacramento, Calif., computer store owner who picked up a block of wood behind his shop on Dec. 11, 1985. It exploded, spewing shrapnel into his chest and up to 150 yards away.

The attack came on the heels of three others that year. Less than a month earlier, on Nov. 15, Nicklaus Suino, a graduate student at the University of Michigan, was injured when he opened a package bomb addressed to his boss, psychology professor James McConnell. A second bomb, mailed to Boeing Co. in Auburn, Wash., was defused June 13.

On May 15, John Hauser, a graduate engineering student at the University of California at Berkeley, was working on his personal computer in a Cory Hall laboratory when he noticed a three-ring binder attached to a small box with a rubber band.

He picked it up to see if he could find out who it belonged to, and when he opened the box, the explosion blew off four fingers on his right hand and severed two arteries in his forearm.

Diogenes Angelakos, who taught electrical engineering, had an office across the hall and was the first to come to Hauser's aid, Hauser remembers. Using a colleague's tie, he fashioned a tourniquet around Hauser's arm.

Angelakos suffered injuries to his right hand on July 2, 1982, in another attack attributed to the Unabomber, when he picked up "something that looked like it belonged to a construction worker" in a common room faculty members used for coffee breaks.

Cory Hall was the only place the Unabomber struck twice. Kaczynski taught math at Berkeley from 1967 until early 1969, but Hauser and Angelakos said they did not know him.

Hauser had to abandon his goal of becoming an astronaut and now teaches engineering at the University of Colorado in Boulder. "It would be nice to know that he is not going to bring harm to anybody else," he said.

Angelakos said, "I would like to ask the guy . . . if he believes in making changes for the good, why would he be hurting people? That's the only thing I'd like to know."

After a bomb injured a Salt Lake City man in 1987 the Unabomber did not strike again for more than six years.

Then, he returned with a vengeance. The next victim was Charles Epstein, a prominent geneticist at the University of California at San Francisco who suffered a broken arm and abdominal injuries and lost several fingers when he opened a padded envelope sent to his home on June 22, 1993. He declined to comment Thursday.

Two days later, Yale University computer scientist David Gelernter ran shirtless, half-blind and bleeding to a medical clinic a block away after a package bomb exploded in his office.

The bomber's last two devices were deadly, killing New Jersey advertising executive Thomas Mosser on Dec. 10, 1994, and Gilbert Murray, a timber lobbyist in Sacramento, on April 25, 1995.

The Unabomber's final bomb was addressed to William Dennison, who had been Murray's predecessor as president of the California Forestry Association.

"I want the full extent of the law brought against him," Dennison said Thursday. "If it's him, I want nothing less than the death penalty."

Percy A Wood