Matching Wits With The Unabomber

Bomb Squad

This story originally appeared in the October 1998 issue of Popular Science.

It was the case of a lifetime, and it had taken nearly a generation to unfold. Federal authorities finally arrested Theodore J. Kaczynski, known as the Unabomber, in a one-room cabin deep in the Montana wilderness, after receiving a tip from his brother. For 17 years, Kaczynski, a math whiz and former college professor, had outwitted the law, waging a war against what he perceived to be the evils of technology. His battle had claimed three lives and injured 22. Many of his bombings had victimized individuals associated with universities or airlines, hence the Un-a-bomber moniker given him by the FBI.

With Kaczynski’s arrest, however, another battle of wits began, one that matched scientific genius gone astray against a three-man team of bomb disposal specialists armed with the latest in technological gadgetry. Although Kaczynski was arrested in April 1996, the role of this special
bomb squad was merely hinted at when President Clinton officially thanked them for their work this past February. Only now, following the May sentencing of Kaczynski to life imprisonment, can their story be told.

The war of wits began when FBI agents peered inside Kaczynski’s tiny cabin and discovered a live bomb, packaged and ready for mailing but unaddressed. Normally, this wouldn’t be cause for too much excitement. A bomb disposal squad would remove the device and explode it harmlessly.

This time was different. The FBI needed the bomb defused but also intact for forensic evidence. The Unabomber had built his devices so they couldn’t be linked to him, and FBI analysis of debris fragments had yielded few clues. The only common threads were the initials “FC,” for Freedom Club, inscribed on eight of the 16 bombs ultimately attributed to the Unabomber, letters from FC to newspapers, and a lengthy manifesto published by The Washington Post and The New York Times in September 1995.

To its credit, the FBI had already realized that defusing a bomb intact was beyond its capabilities. In August 1995, FBI agents turned for help to Chris Cherry, a researcher at Sandia National Laboratories, a federal weapons research facility in Albuquerque, New Mexico. Cherry, a Department of Defense veteran of classified operations, is considered by those in the secretive bomb technician community to be the dean of bomb disposal experts. For the next nine months, Cherry would be on standby in case a Unabomber device was intercepted before it exploded. Cherry’s team would include veteran Sandia assistant Rod Owenby and Vic Poisson, a long-time friend and associate with the Riverside, California, police department.

Shortly after Kaczynski’s arrest, Cherry and Poisson were on the phone discussing the case when Cherry’s other line buzzed. It was 6:30 p.m. on Good Friday, and Cherry was looking forward to Easter with his wife. Cherry put Poisson on hold and picked up the other line. It was the FBI.

“We have a device,” said the agent on the other end of line. “It’s under the bed [in Kaczynski’s cabin].”

Cherry quickly switched the line back to Poisson. “Don’t hang up.”

The PAN Disrupter

The FBI immediately dispatched planes to bring Cherry’s team members and their gear to the scene. Owenby was excited on the plane. The airport pickup had been conducted like a clandestine operation. Only first names were used, and no questions were asked.

“Isn’t this neat?” Owenby asked Cherry.

“It will be if we’re successful,” replied Cherry, who was beginning to sense the pressure. At that point, Cherry thought he would be gone from home for two days at most. He hadn’t anticipated what lay ahead.

By 7 a.m. the next morning, the three men had arrived at the site in Lincoln, Montana. The cabin was a few miles south of town, 500 yards up a narrow trail through a forest. It sat astride the Great Divide of the Rocky Mountains at 6,376 feet above sea level.

The three passed through multiple checkpoints, each manned by federal agents toting machine guns. Finally, they saw the cabin in the light of a beautiful spring morning. “It looked like a storage shed at one of our houses,” remembers Owenby. Since 1971, it had been Ted Kaczynski’s home.

Accompanied by a FBI agent, each of the three was led one at a time to the door of the 10- by 12-foot cabin. It was crammed with books, boxes, jars, and—ominously—chemicals. A later inventory would reveal that the chemicals included bottles of sulfur, saltpeter, ammonium nitrate, and sodium chlorate; the boxes contained zinc, aluminum, and lead. One old cereal box contained 23 bomb igniters, each made from a piece of cord pulled through a wooden plug. Other boxes contained batteries; wiring; and pieces of metal, copper, and plastic pipe.

The cabin lacked running water, electricity, and a bathroom. It had a pot-bellied stove for heat; a table, a chair, and what appeared to be an army cot were the only furniture. The bomb was under the cot.

All three also noticed two other items lying in plain sight—the hooded sweatshirt and sunglasses depicted in the FBI’s sketch of the suspect, which had been widely circulated in the media. The sketch was based on an eye-witness description following a February 1987 bombing in Salt Lake City.

The cabin and all of its contents would be saved as evidence, but the first order of business was to get the bomb out of the cabin and moved to a safe location. The bomb, like many of the Unabomber’s past devices, was packaged in a rectangular wooden box, the size of a thick book,
that would fit inside a mailbox.

Cherry’s team constructed wooden ramps up and into the cabin, and a remote-controlled robot carefully carried the device to a nearby field. The bomb was then placed on a wooden stool; the team built an igloo of heavy timbers around the stool, covering the structure with a blue tarp held down by sandbags. Nobody was overly concerned that the bomb would detonate while it was being moved, because Kaczynski’s bombs were always designed to explode when they were opened. But from this point on, the wooden structure would contain any explosion, with the blue tarp acting like a big tablecloth to capture any forensic crumbs.

The cabin, meanwhile, turned out to be a treasure trove of clues. Perhaps most important were 10 notebooks authored by Kaczynski. “His notebooks were like a technical memoir,” says Cherry. “My main focus was on how he thought about explosives and bombs. He had a very elaborate set of notes written in Spanish. It was just unbelievable.”

Simple But Deadly

Fortunately, Cherry was able to have Kaczynski’s notes immediately translated, and what he learned helped him understand Kaczynski’s approach to bomb-making and gave him great cause for concern. “His notes told me that he was a mathematician,” says Cherry. “In one entry, he was trying to calculate heat transfer on a bridge wire of the type used in detonators, looking at the electric current relationship involved. He was looking at bomb-building from a scientific viewpoint. And that’s what impressed us.”

Cherry would soon be informed that Kaczynski had received a Harvard degree at 20, earned a doctorate at the University of Michigan, and had been a mathematics professor at the University of California, Berkeley. His mathematical treatises, published in the 1960s, were considered by his peers to be the work of a genius.

The notebooks only confirmed what Cherry already knew. Kaczynski was a formidable bomb builder who had improved his technique with each succeeding device between 1978 and 1995. Cherry also was one of the few people who realized that Kaczynski had recently achieved a technical breakthrough that doubled the destructive power of his bombs without increasing the size of the package. Cherry says this technique was known to only a small number of people, and that number did not include any FBI agents.

“Kaczynski was right on target, technically,” says Cherry. “What amazed me was that this guy was doing all this by himself. You’re dealing with a guy who has no electricity. He’s using hand tools. But at the same time he’s producing devices that are extremely deadly. As he progresses, the fatalities increase.”

Cherry was also impressed with Kaczynski’s patience. Every component of his bombs was handmade. “He may have spent weeks working on one little component. He was so careful about not leaving a trace, other than the Freedom Club inscription.”

Poisson agrees with Cherry’s assessment. “It was very clear that Kaczynski thought out each and every minor detail, and had probably gone through extensive testing of each device. He was truly unique.” Ironically, Poisson, Cherry, and Kaczynski all had the same hobby in high school: building fireworks.

The team decided that the job would be handled in two phases: The first would render the bomb inactive, while the bomb would be dismantled in phase two. “Our goal was to go backward from the completed item to what was existing on the table when it was started,” explains Poisson. Phase two would be as dangerous as phase one, however, since many of the individual components were explosive. Essentially, the team was looking at bombs within a bomb.

By Sunday, the team was ready to begin disarming the bomb, but only after spending most of the preceding night arguing about how to proceed—a discussion punctuated by lack of sleep and too much coffee. Each team member had a different opinion. X-ray imaging systems had provided them with some idea of the interior layout of the bomb, but the two-dimensional pictures proved hard to interpret in three dimensions, so the exact location of the triggering device was difficult to pin down.

“The whole device was hard to interpret,” says Owenby. “Things in it were odd, and the way it was put together was odd.”

The team was at an impasse. The FBI liaison, Tom J. Mohnall, an explosives examiner from the FBI’s laboratory in Washington, D.C., looked at Cherry. “You’re in charge. You’re calling the shots.” Cherry’s interpretation of the bomb’s interior would stand.

The gear needed for the job was ready to go. The team is reluctant to reveal details about the equipment they use, concerned that such knowledge may give future bombers an edge. Much of it, however, involves remote video systems and robotic manipulators of various sizes that can be operated from a safe distance.

The whole device was hard to interpret. Things in it were odd.

“The days when you see a guy cutting a red or green wire, like in the movies, are over,” says Cherry. “We can do that type of task from a mile away.”

One key device, in use for only a few years and invented by Cherry under an FBI contract, is called the Percussion Actuated Nonelectric (PAN) disrupter. It hovers over the bomb like a praying mantis about to devour a bug. “It basically allows us to use an explosive to disarm an explosive,” says Cherry, but that is as much as he will say about it, even though it is now used by bomb squads nationwide since the FBI distributed 500 free of charge last year. As described by Patrick J. Webb, a counter-terrorism supervisor for the FBI who was also on the scene and had tracked the Unabomber since 1982, the PAN disrupter is a long narrow stainless steel tube about an eighth of an inch in diameter, through which many different kinds of high-powered charges can be fired. The shock tube, as it is called, is manufactured in lengths up to 5,000 feet, so it can be cut to any desired length, letting the bomb squad remain at a safe distance from the explosive. When fired with a basic black powder round, as was used in this case, the PAN disrupter creates a flash that looks like a bolt of lightning, signaling that a shock wave is traveling down the tube. When the device performs correctly—Webb can’t recall it ever misfiring—the shock wave will disable a key component of the bomb, such as the trigger, timer, or battery. The PAN disrupter, says Webb, is the only scientifically verified tool available to bomb technicians. It has been tested so many times with a variety of charges that technicians need only consult a guidebook that will correlate a bomb type to the correct charge, approach angle, and stand-off distance in which to use the disrupter. Fortunately, most bombs seen in the United States, about half of which are pipe bombs, are of simple construction. “We haven’t seen a ramping up of sophisticated technology,” says Webb. “We’re still in the bomber Stone Age.” Nevertheless, he acknowledges, the Unabomber had proved how deadly even primitive materials can be in a bomber’s hands.

With the PAN disrupter in place, Cherry allowed Jim Freeman, head of the FBI’s San Francisco office and who, along with Terry D. Turchie, headed the Unabomber investigation, to fire the device.

The Unabomber’s Tools

“Is it going to be loud?” asked Freeman.

“We hope it is a quiet, joyful noise,” replied Owenby.

A few seconds later, a small, muffled thump caused all three team members to grin. Cherry was the first to inspect the Unabomber package. The operation was a success: The package had barely moved. “It was so surgically defused, you couldn’t tell it was defused,” says Cherry. Phase one was over.

As expected, phase two proved more difficult. The team had prepared a number of special tools for the task of dismantling the bomb, most of which were invented for the assignment and wouldn’t be immediately comprehensible even to your average bomb technician. Again, the team is circumspect about details. “We may need certain technologies tomorrow,” says Owenby.

Still, what the team knew about the Unabomber’s previous bombs wasn’t reassuring. “He was unusual in that most bombers have a particular way of doing business,” says Poisson. “He was exceptionally difficult to deal with, because he did whatever appealed to him at the time.”

Adding to the difficulty were the Unabomber’s handmade components, which included even the screws. Kaczynski’s homemade glues were manufactured from animal hooves and tended to react unpredictably compared with store-bought material.

In taking apart a bomb, the general idea is to apply heat extremely slowly over a period of hours, in increments of as little as one-tenth of a degree, in the hope that this will cause the components to eventually separate. The difficulty with this approach is that the bombs tend to be so tightly constructed that moving even a single element takes a precise amount of energy. Too much heat or too much movement will cause an explosion.

Each move on the bomb prompted a lot of discussion, but slowly the components begin to peel away, one by one, much as the team had expected based on their analysis of previous Unabomber devices.

Then they hit a wall.

“This guy was unbelievably clever,” says Cherry. “We trained so that when we got to any given point, we would know a certain set of tools and gear were needed. Well, guess what? He threw us for a 180-degree turn. We said: ‘Now what do we do?'”

Cherry won’t say exactly what the problem was, for security reasons, but he likens it to expecting to see something in liquid form, then discovering that it is reinforced concrete and that the cup you brought is useless. Nothing in the technicians’ toolbox would allow them to proceed. Cherry felt as if he were on third base, prepared to score the winning run of the baseball game, only to learn that all the bats were now broken.

Poisson, the team’s primary gadget maker, was undeterred. After studying the problem for the better part of a day, Poisson stole into a nearby farmer’s toolshed while its owner was away, and improvised a tool on the spot. Working with an untested tool can be extremely dangerous, and Poisson recalled the old bomb squad adage: “It’s either initial success or complete failure.” Nonetheless, the team decided to continue.

Making matters worse, the bomb began to behave erratically. An initial application of heat would yield no reaction, then suddenly there would be a spike in the temperature reading that could cause an explosion. Heat was dissipating from one part of the bomb but not from another. No one knew the temperature threshold that would cause the bomb to explode. Temperatures rose, and the team backed off until the device cooled. Again and again, they followed the same procedure. “Add energy” and “stop” became a mantra. After each pause, Cherry would personally inspect the bomb, looking for signs of discoloration or residue buildup.

“The TV systems could give us a look but they couldn’t tell us certain things,” says Cherry. “We needed a three-dimensional view of how the energy was affecting the device. Every second, we were concerned because we were putting so much energy into something that was so sensitive. And we didn’t know exactly how sensitive it was. I could only speculate on what I saw, what was in Kaczynski’s notes, and what I thought we had, based on my past experience.”

Slowly, over a period of hours that stretched into one nerve-wracking day after another, the bomb came apart. Poisson’s untested, jerry-rigged tool had worked like a charm. Nine days had passed since the team’s arrival at Kaczynski’s cabin. And piece by piece, they had handed over the Unabomber’s last bomb into evidence.

A little more than two years later, on May 4, 1998, Ted Kaczynski pleaded guilty in federal court in Sacramento, California, and was sentenced to life imprisonment without any possibility of parole. By agreeing to the plea, Kaczynski avoided the death penalty. The case never came to trial. The dismantled bomb was never presented to the court, and it’s stored at the FBI’s Washington, D.C., lab. Kaczynski’s cabin now sits in a warehouse in a former Air Force base outside of Sacramento.

This story originally appeared in the October 1998 issue of Popular Science.