Are the disappearances or deaths of at least 11 US scientists, each allegedly connected in some way to space, defense and nuclear research, really linked in a nefarious plot: one that involves the Chinese or other state enemies, or possibly links back to UFOs?

A conspiracy theory positing exactly that has roared through sections of the US population in recent weeks, spreading rapidly from the internet into rightwing media and hence into the mainstream press and prompting an inquiry from Congress and questions from Donald Trump.

Could such an outlandish theory have even an inkling of truth? Or are lawmakers, the FBI, the White House, countless substackers and podcasters, along with US media outlets, just pandering to the latest clickbait conspiracy theory in an age rife with them?

Like all good conspiracy theories, the mysterious case of the sudden flood of missing or dead US scientists is difficult to sift through. And answers to its puzzle likely lie not in the conspiracy theory itself but what it represents in an era of AI slop and social media disinformation. Especially when each morsel of conspiratorial connection creates more appetite for another and can never be satiated.

But there are a few known elements.

On 27 February, the retired US air force major general William “Neil” McCasland, 68, walked out of his house in Albuquerque, New Mexico, some time between 10 and 11am. His phone and glasses were left behind, he took his .38 revolver, and he is believed to have left on foot. His wife found that he was missing soon after midday. That afternoon, the Bernalillo sheriff’s office issued a silver alert – a bulletin when an older person goes missing.

Nothing has been seen or heard from McCasland since. But as a former commander of the Kirtland air force base’s Phillips research site and laboratory, which focuses on space vehicles and directed-energy technologies, his disappearance raised eyebrows, including within the UFO community.

Lt Kyle Woods of the Bernalillo county sheriff’s office told reporters nothing has been ruled out, “which is why we’re investigating every possible link that we can”.

Woods added: “I appreciate that there’s a community that wants to go down the rabbit hole of UFOs. I don’t have a way with which to pursue that and so those theories have to be set aside unless we were to find something that would have indicated that. So we can only go off the facts.”

But facts were scarce. And into that void soon poured other accounts of missing or dead scientists, often with real or imagined links to national security or space work.

Reports eventually surfaced of at least 10 missing or dead scientists. They included Michael David Hicks – a scientist who worked at the Nasa jet propulsion lab from 1998 to 2022 and studied near-Earth asteroids and comets. He died from unknown causes at the age of 59 in 2023.

Another scientist, Monica Reza, disappeared in June last year. She served as director of the Nasa lab’s materials processing group. She had set out on a hike in the Angeles national forest with a companion. A police report said Reza, 60, was about 30ft behind her friend when she disappeared. Her body was never found.

Others added to the list include astrophysicist Carl Grillmair, shot dead on his porch; MIT physicist Nuno Loureiro, killed by a former classmate; and Jason Thomas, a chemical biologist at drugmaker Novartis, who disappeared in December. His remains were discovered in Massachusetts in March.

Another name is Amy Eskridge, an Alabama-based researcher who claimed to be working on “gravity-modification research”. Eskridge died by suicide in 2022. But last week, Franc Milburn, who claims to be a former British intelligence officer, told NewsNation that Eskridge told him not to believe any reports that she had died by suicide if she turned up dead.

“If you see any report that I killed myself, I most definitely did not. If you see any report that I overdosed myself, I most definitely did not. If you see any report that I killed anyone else, I most definitely did not,” Eskridge texted, according to Milburn.

The accounts were published breathlessly online in social media but also by rightwing press accounts. Trump himself was asked about the story and promised to look into it. Soon, Republican lawmakers joined the debate demanded in a letter that the FBI, the Department of Energy, Nasa and other agencies investigate a “possible sinister connection” in the disappearances.

“These reports allege that at least 10 individuals who ‘had a connection to US nuclear secrets or rocket technology’ have ‘died or mysteriously vanished in recent years’,” wrote Kentucky Republican James Comer and Eric Burlison of Missouri last week in a letter to multiple law-enforcement agencies demanding action.

“If the reports are accurate, these deaths and disappearances may represent a grave threat to US national security and to US personnel with access to scientific secrets,” they added, citing an additional two workers affiliated with the Los Alamos National Laboratory who have died or or gone missing.

They wrote in a letter to the secretary of the department of defense, Pete Hegseth, that Reza and McCasland may have had a “close professional connection”.

Then, last week, UFO researcher David Wilcock, 53, used a gun to kill himself outside his home in Boulder county, Colorado. Tennessee congressman Tim Burchett responded to a social media post announcing Wilcock’s death by writing: “Not cool.” Burchett told the Daily Mail: “I just don’t think there’s any chance that this is just all coincidental.”

But is there anything more than coincidence that 11 out of more than 2 million scientific researchers in the US, or an estimated 700,000 with top-secret aerospace and nuclear clearances, can variously go out hiking and disappear? Or perhaps chose to end their lives, especially if they might have had mental illness or paranoid delusions? Or fall victim to murder?

Experts say it is the onlookers – us – who chose to make connections when, in reality, there are none.

The latest uptick in alien/nuclear mystery fears, says Greg Eghigian, professor of history and bioethics at Penn State and author of After the Flying Saucers Came, is different from the New Jersey drone scare of late 2024.

“It’s one of those things that get folded into other kinds of concerns and conspiracy theories that are out there about science and medicine that have been circulating around since Covid,” Eghigian said. “That fold neatly into the decades-old notion that UFOs are spotted around nuclear facilities and some of these facilities may be masking UFO-related projects.”

All of it seems to be a convergence, he adds, “so when people want to connect these dots it falls readily into a sweet spot for UFO lore because you have all the elements that have always been there – the military, state secrets, nuclear facilities and technologies, and fear of figures that are missing. What is it? Are they being abducted? Assassinated because they know too much? The seeds of this were planted decades ago.”

The mystery – or lack of it – comes at a moment of heightened national security anxiety that is often accompanied by increased reports of UFO sightings or alien abductions by people or institutions with an interest in promoting richly imaginative theories that can neither be proved nor disproved.

Podcaster Joe Rogan, one of the most powerful figures in US media, recently suggested – unhelpfully – that the disappearances could be to do with “plasma technology, whatever the fuck that is”.

It is McCasland’s wife, Susan McCasland Wilkerson, who stands as the best debunker of any mystery surrounding her husband’s work, explaining that he had once had access to classified information but had retired nearly 13 years earlier.

In a wry tone that used humor to try and defuse the conspiracy theories starting to sprout up around him, she took tongue-in-cheek aim at those wishing to believe something sinister was going on.

“It seems quite unlikely that he was taken to extract very dated secrets from him,” she wrote in March before the theory had even spread too far. She said his past association with Tom DeLonge, former Blink-182 singer and a figure in UFO/UAP (unidentified anomalous phenomena) disclosure effort, “is not a reason for someone to abduct” him.

Nor, she said, did her husband have “any special knowledge about the ET bodies and debris from the Roswell crash”.

No sign of her husband has been found, she said, so “maybe the best hypothesis is that aliens beamed him up to the mothership. However, no sightings of a mothership hovering above the Sandia Mountains have been reported.”