'The Unabomber Was an Incel. I'd Know—I Worked on the FBI Investigation'

It's hard to believe that a whole quarter of a century has gone by since Ted Kaczynski, otherwise known as the Unabomber, pleaded guilty to all federal charges against him.

When I joined the FBI's UNABOM Task Force (UTF) in July 1995, about a year after it was formed, it had been an active case for 17 years. The Unabomber had sent 16 bombs, mostly to universities and airlines, and three people had been killed. He had gone dark in 1987, and didn't offend for about six years, but in 1993 he came back with a vengeance, which was why the UTF was formed.

At the time, I was a seasoned criminal investigator, with 17 or so years under my belt as a police officer in the suburbs of Philadelphia and as part of the FBI's Bank Robbery Taskforce in New York. I knew how to find the visible clues of a crime scene but now, in my new position as a criminal profiler, I was looking for invisible clues.

A profiler looks for behavioral clues at a crime scene that help us put together a picture of what kind of offender is committing a particular type of violent crime. We look at the victims he chooses, how he gets into a scene, how he leaves a scene, and the technique used to commit the crime. But we also look at his signature—activities unnecessary for the successful completion of the crime, yet undertaken because it fulfils some kind of sexual or personal need for the offender. This could be keeping a victim's lock of hair or driving license, for instance.

Unabomber was my first case as a profiler. After I graduated from the FBI's profiling school, I got a call from my boss asking if I wanted to go to San Francisco for 30 days. They wanted a profiler on site to help develop a behavioral strategy on the case. Those 30 days turned into a year-and-a-half.

It was intense. I had a young family and I was away from them a lot. I was living this thing full-time and doing long days—on a short day I was working 10 hours—six-and-a-half days a week. But I knew I was doing something important. I wanted this case solved.

My first breakthrough

I was given a large three-ringed binder to take with me on the six-hour flight to San Francisco from Washington so I could catch up on all the facts of the case. Going through that binder, I noticed the second letter the Unabomber ever wrote, to trick a University of Michigan professor into opening a package containing a bomb.

Just before the flight was about to land, I looked at this letter and saw it almost like a photograph: just a piece of paper with symbols on it. And that's when I saw that the letters at the beginning of every line, from top to bottom, spelled out: "Dad it is I." No-one had told me about this before. It was an acrostic.

When I told the big boss, he said, "From now on, you're in charge of all the language analysis in this case." So I focused on what I could determine from the numerous letters and the 35,000-word manifesto that had been sent to the New York Times but was not yet public knowledge. That's how my role in the investigation began, and how I eventually helped solve the case.

Initial profile of the Unabomber

Within the UTF, there were a number of theories around the Unabomber's identity. One of the predominant ones was that he was a mechanic who had been laid off by United Airlines in the late-1970s, as the president of United Airlines was the Unabomber's fourth victim.

But there were other theories: there was a squad looking into Dungeons & Dragons players; another looking at former and present military or law enforcement who had bomb-making experience; and there were those who thought this was the work of the Zodiac killer, a serial killer in California who operated in the late 1960s and has never been identified.

Because the first bombing occurred at a university campus in Chicago, the team put the age of the bomber as a college student, 20 or 22. They always felt he was not highly educated but he was clever with tools, as he knew how to make sure no evidence was left on any of his devices.

He was probably single but, if married, it was a relationship where he didn't talk to his wife much. He would need a separate room or a garage where he did his bombing work, but it was also likely that he lived alone.

The original profile wasn't that far off—except for age and education. But when I came on board and had the benefit of reading the manifesto, and looking at some other letters, we were able to fine-tune the profile, so near the end it was very close to Ted Kaczynski.

Finding hidden messages

Any time a violent, serial offender is willing to provide 35,000 words of his own thinking, it opens up numerous windows into his mind. I realized this manifesto, and the letters he had written to the New York Times and to his victims, were a treasure trove of information that no other case, of which I was familiar, had ever provided before.

From his use of archaic words—he referred to women as "broads" and he referred to Black people as "Negroes"—and references to older editions of books, we could decipher that he was older than we had previously assumed.

The most noteworthy change I made to the profile, however, was the result of two letters: one to the New York Times, and another to a professor at Yale University.

In the letter to the Yale professor, the Unabomber wrote: "People with advanced degrees aren't as smart as they think they are." This was sort of an insult to the professor and, indirectly, a compliment to the author. He seemed to be acknowledging that he didn't have an advanced degree, yet was smarter than the professor.

In the same letter, I saw this sentence: "Apparently, people without a college degree don't count." By indication, the author seemed to be saying he did not have either a college degree or an advanced degree.

This was the first autobiographical information the Unabomber had supplied about himself in any way, shape or form. So I knew it must be a lie. This guy was too clever. His bombs were perfect in terms of their functionality; they always exploded and left no evidence on them. Why would he tell people he didn't have a college degree? No, instead I believed he had a college degree—and, since he was the one who brought up advanced degrees, he probably had one of those, too. We later found, of course, that Kaczynski had a master's and PhD in mathematics.

This ties in with another letter he wrote to New York Times, when he first proposed publishing his "article"—he never called it a manifesto—and he wrote that he was getting tired of going into the Sierra Nevada mountains at night and on the weekends, practicing his bombing techniques.

Why was he telling us where he lived? And why was he implying that he had a full-time, Monday through Friday, 9 to 5 job? So I thought, guess what, this guy doesn't live anywhere near the Sierra Nevada, and he doesn't have a full-time job: or certainly not Monday through Friday.

That helped us add to the profile from a geographic perspective and a working professional perspective. It didn't give his name or his address, but it helped us narrow down our suspects from 2,500 to a few dozen—although none of these were Kaczynski.

A few months later, when the manifesto was published in the press, we got a phone call about a guy called David Kaczynski, who had a brother called Ted. Once we learned more about Ted Kaczynski, we found he fit the profile almost to a "T", so we pursued this further.

David Kaczynski provided the UTF with over 175 separate writings of his brother which his family had retained over the years. My team at the UTF then matched the various topics, themes, syntax, semantics, lexicon, and overall style to the Unabomber letters and manifesto. Upon categorizing over 600 distinct examples of such, I was convinced that Kaczynski and the Unabomber were one and the same person.

We obtained a search warrant and searched Kaczynski's cabin and found bomb-making materials, his original handwritten copy of the manifesto and the 1930s typewriter he had used. This led to his arrest that same day.

Why I believe the Unabomber was an "incel"

Once we got inside Kaczynski's cabin and read everything he ever wrote—around 1,000 different communications he wrote to himself, including an autobiography, a journal and stapled pages of notes—we found our previous suspicion seemed to be true: he had never had a relationship with a woman in his life.

He was so desperate to meet a woman, he had written personal ads in the San Francisco Chronicle and Mother Earth News, seeking a woman to live with him in the mountains. He got a few responses, but they never bore any fruit.

Kaczynski was, by his own writings, a straight male who had never had sex with a woman, and that greatly frustrated him. The word "incel" wasn't around back then, but I believe that's what he was.

Almost every woman he referenced in his writings would be described as a nice, pretty and smart young girl but, before long, she somehow turned on him or insulted him. Worst of all: she ignored him, as if he didn't exist, and went off with one of the "cool guys." He wrote about having violent fantasies of wanting to murder or torture these women. These were personal writings that he never meant for anyone to read.

While I think he never had the wherewithal or the personal confrontational skills to attack a woman—which is a good thing—I believe sexual frustration was the basis for much of the Unabomber's activities and actions. I have no doubt that his violent, homicidal ideation was rooted in his frustration in not being successful with women.

When Kaczynski was sentenced to two life sentences, I was fine with that; it meant he would never see the light of day again.

In the past 25 years, I've been a free man, which I think I should be; Kaczynski has not been a free man, which I think he shouldn't be. I believe we're both where we belong.

James R. Fitzgerlad retired from the FBI in 2007, but remains an active criminal profiler and forensic linguist with his company, James R. Fitzgerald Associates, LLC. He was a technical advisor for CBS' series, Criminal Minds, among other shows. He is also the author of the book series, A Journey to the Center of the Mind. Find out more at his website: jamesrfitzgerald.com

All views expressed in this article are the author's own.

As told to Newsweek's My Turn deputy editor, Katie Russell.