WASHINGTON — Social media have altered the motives and targets of those who set out to kill public figures, spreading the threat beyond politicians to music stars, athletes, and other pop-culture icons, according to a study by a senior FBI official and a prominent forensic psychologist.
The study, which will be published online Wednesday in the journal Behavioral Sciences and the Law, aims to update a landmark Secret Service report that examined attacks on public figures between 1949 and 1995, ending with ‘‘Unabomber’’ Ted Kaczysnki.
That report, which looked at 83 attackers, found that 68 percent of targets were government or judicial figures, while 19 percent were celebrities.
The new study is narrower — 58 attackers from 1995 to 2015 — but it found that 38 percent targeted government or judicial figures, while 34 percent focused on movie, sports, and media celebrities.
The authors attribute that shift to Facebook, Twitter, Instagram, and other social media, which have fueled a culture of celebrity and created an illusion of intimacy with stars.
For some attackers, especially the one-third who are delusional, this digital relationship feels like a personal connection, with a seemingly two-way conversation that amplifies infatuation.
At the same time, the public figures traditionally stalked by assassins — politicians and other government officials — have lost some of their appeal, the study found. They aren’t seen as powerful symbols whose deaths will provide eternal infamy. Rather, attackers blame them for their troubled lives and are seeking retribution, a motive that puts pop-culture figures at risk, as well.
‘‘These attacks are now angry and personal,’’ said J. Reid Meloy, lead author of the new paper and a professor of forensic psychiatry at the University of California San Diego. ‘‘They don’t want fame. They want revenge for some perceived wrong.’’
Meloy and coauthor Molly Amman, the program manager in the FBI behavioral-analysis unit that studies targeted attacks, coined a term for this new breed of targets: publicly intimate figures. And social media don’t just offer attackers this faux connection. They can also tip them off to where a target might soon be.
In the paper, the authors describe dozens of victims who are public figures: Paris Hilton, attacked outside a courthouse by a stalker; Tom Brokaw, targeted with anthrax, allegedly by a disgruntled researcher wanting more money; and Roanoke television reporter Alison Parker, killed on live TV by an angry former co-worker.
Given the timeline of the study, the authors could not include this summer’s fatal shooting of Christina Grimmie, a former singer on ‘‘The Voice,’’ by a man obsessed with her social media posts. He lost weight and became a vegan to try to win her heart. But that attack, Meloy said, is an important example of his study’s findings.
Reaction to the study in threat-assessment and criminology circles was mixed.
‘‘To those of us involved in threat assessment, this is data that confirms what we have been observing,’’ said Mario Scalora, who directs the Targeted Violence Research Team at the University of Nebraska.
Marisa R. Randazzo, the former chief research psychologist at the Secret Service and now managing partner at Sigma Threat Management, said, ‘‘The reason why this is such an important study is that it provides a comprehensive view of the wide range of people who have become targets because of their public-figure status.’’
But other experts raised questions about the study’s methodology, arguing the data did not offer an apples-to-apples comparison with the earlier study and that the tally of attacks could be incomplete, because they were identified by Google searches. Also, those arrested weren’t interviewed, limiting the insights into motives.
The authors acknowledged these potential shortcomings in the paper. (The authors of the previous study did not respond to requests for comment.)
Adam Lankford, a University of Alabama criminal justice professor who studies suicide bombers and mass shooters, questioned some of the methodology but said the trends described seemed plausible, given obvious changes in society. Like the authors, he is curious about the evolution of people seeking fame through violence.
He pointed to the rise of mass shootings, noting that those attackers are often disturbed fame-seekers, emulating and even competing against previous shooters.
‘‘It makes sense that people who grew up in the ’60s, ’70s, and ’80s who wanted fame were more likely to attempt political assassinations,’’ Lankford said. ‘‘Today they are more apt to commit mass shootings.’’
The authors argue that fame has become a lesser motive in attacks on public figures because social media provide the opportunity for anyone to become a star.
‘‘One could observe that it may be less necessary than in the past to engage in assassination in order to become famous,’’ they write. ‘‘The Internet and social media make it possible for anyone with access to technology to achieve fame with little effort.’’
Instead, attackers target public figures out of anger for some slight, real or perceived.
The study did find numerous aspects of attacks on public figures that have remained constant. The attackers are almost always male. They are often mentally disturbed. They don’t make direct threats before taking action.
A spokeswoman for the Secret Service said the agency has reviewed attack trends, releasing a report last year. That report looked only at attacks on federal buildings and employees. The primary motive: ‘‘Retaliation for a perceived personal slight or wrong.’’ Fourth on the list: ‘‘Seeking fame or attention.’’