Mass shooters do not often end up on trial. Many are killed or take their own lives in their attacks, some leaving behind a manifesto explaining why they acted, others leaving a mystery.
But in a trial that ended on Thursday with the imposition of a death sentence, scores of witnesses took turns dissecting the life and motivations of one middle-aged man who lived alone in a small apartment before carrying out the deadliest antisemitic attack in U.S. history: the killing of 11 worshipers in a Pittsburgh synagogue on Oct. 27, 2018.
From the testimony of prominent psychiatrists and aging relatives emerged a portrait of the gunman, Robert Bowers, that was at once shocking and strangely familiar. It depicted an isolated, unhappy man who had grown obsessed with dark and deranged ideas, such as the notion that Jewish people were part of a conspiracy to destroy the white race.
“I see how the first time you hear it, it sounds pretty crazy,” Dr. Park Dietz, a forensic psychiatrist explained to the jury in testimony in early July. “But when you have seen this promoted for 20 years, 40 years, among thousands and thousands of people, in their books and the propaganda and online forums, it’s clear that these are subcultural beliefs.”
The defense lawyers, argued that Mr. Bowers’s troubled childhood and mental illnesses had fueled bizarre, apocalyptic delusions. But Dr. Dietz and other experts who testified for the prosecution said that the defense “simply mistook very ordinary widespread white separatist beliefs for delusions because they weren’t familiar with them.”
If the government’s argument ultimately convinced the jury, and brought some measure of relief to the people who sat in court just a few steps away from the man who killed their loved ones, it was an argument that experts say should give little comfort to anyone else.
In the online far-right fever swamps that have grown immensely since the synagogue massacre, the views Mr. Bowers expressed on social media five years ago would be “simply unremarkable,” said Oren Segal, the vice president of the Anti-Defamation League’s Center on Extremism.
“There are thousands upon thousands upon thousands of people saying that stuff and even worse,” Mr. Segal said.
Other experts in threat assessment agreed that there was very little about what Mr. Bowers appeared to believe that was exceptional.
The idea of the “great replacement” — that elites, and often specifically Jewish people, are bringing in darker-skinned immigrants to “replace” white Americans — has been echoed by other purveyors of violence but is also expressed routinely on right-wing websites. A more muted version of the “great replacement” theory was standard fare on Tucker Carlson’s show on Fox, which drew millions of viewers every night, and has even been espoused by members of Congress.
Andrew Torba, the chief executive of Gab.com, a far-right social media platform where Mr. Bowers wrote and shared hundreds of virulently antisemitic posts, testified at the trial that there were about 800,000 accounts on the site in 2018. In a 2022 corporate filing, Gab reported having nearly six million accounts, though it was unclear how many were active.
“Technology has advanced in the last five years, and so there’s more ways of creating engagement over hatred of Jews or other communities,” Mr. Segal said.
There are now instruction manuals online for white supremacist would-be terrorists, he said, and propaganda videos telegraphing bigoted harassment or even violence to the widest possible audience, an avenue for self-promotion far beyond Mr. Bowers’s terse post on Gab before the shooting. Mr. Segal pointed out that the 19-year-old white man who shot and killed 10 Black people at a grocery store in Buffalo in 2022 — who had carved Robert Bowers’s name onto his gun — livestreamed the massacre.
In an online sea of hateful and violent rhetoric, it has become ever more challenging to spot the true threats. There are certain signals that threat assessment experts look for, said Molly Amman, a former F.B.I. profiler who is studying the Bowers case. These include, she said, a radicalized view of the danger posed by some group of outsiders, and “a sense that something is fundamentally changing,” that “what I’m doing is no longer enough.”
The psychiatrists and other experts who interviewed Mr. Bowers said in their testimony that he expressed this kind of visceral urgency to act, seeing it as a duty to protect his culture from invasion. But he said as much openly on Gab. Statements like this are all over the internet, and the notion that civilization is being pushed to the edge of collapse has become a standard trope of political and media rhetoric on the far right.
There is a combination of different factors that increase the chances someone will become a dangerous risk, said Robert Pape, the director of the University of Chicago Project on Security and Threats. It is a pattern apparent in other recent cases of violence — such as the mass shooting in El Paso in 2019 and the attack on Paul Pelosi last year — and it was present in Mr. Bowers’s case as well.
He was an already volatile man, perhaps suffering from lifelong mental disorders. After the death of his grandfather and his one close friend, he was isolated and alone. He spent his days online, immersed in conspiracy, what Mr. Pape called “self-brainwashing.” And he became convinced that there was a threat manifesting, a “great replacement,” and that it was his duty to act.
Some of the factors that converged in his case are only intensifying nationwide. Extremist content continues to mushroom online, while the U.S. Surgeon General has warned of “an epidemic of loneliness and isolation.” Men in particular have grown more socially detached.
Mr. Pape said it was too simplistic to declare that the growth of these trends means there will be more horrific tragedies.
But, he added, “we should prepare as if there will be more.”
Jon Moss contributed reporting.