Speculation about links among a handful U.S. scientists who have died or disappeared in recent years was largely confined to niche online communities less than two months ago. As of Friday, the number had grown to at least 12 and was at the epicenter of U.S. government, with both the FBI and Congress investigating possible connections.At a press gathering April 16, President Donald Trump was asked about “10 missing scientists with access to classified stuff, nuclear material, aerospace, they’ve all gone missing or turned up dead in the last couple of months” and whether he thought there were ties among them.“Well, I hope it’s random, but we’re going to know in the next week and a half, ” Trump said.Those speculating about the cases suggest that the individuals were targeted, perhaps by global U.S. adversaries, because of the sensitive nature of their work related to topics such as astrophysics, nuclear weapons and pharmaceuticals. But so far no evidence has been found that definitively links them or establishes coordinated foul play.

Jen Golbeck, a professor at the University of Maryland who studies conspiracy theories, said the idea of a sinister connection between tragedies involving scientists is a common trope within conspiracy theory communities.“There are a lot of people who work for national labs and universities and government research centers and some of them will go missing or commit suicide or die,” she said. “Any year you could take a bunch of those and name them as something sinister if you wanted to.”