Scientists are vanishing or turning up dead. Now ex-FBI boss reveals chilling plot likely unfolding… and who he fears is behind it

As the string of mysterious disappearances and deaths among America’s scientists grows, a former FBI boss believes a sinister plot against the US could be unfolding.

Chris Swecker, who was the assistant director in charge of the bureau’s Criminal Investigative Division during his 24-year career, told the Daily Mail that foreign powers could be targeting citizens who have knowledge of national security secrets.

‘The first thing you go to is it’s potential espionage,’ he said. ‘Our scientists have been targeted for a long time, especially in the rocket propulsion area, by hostile foreign intelligence services.’

A disturbing pattern has been developing after a former Air Force general, a top NASA scientist, and two employees from one of the country’s major nuclear research labs all vanished without a trace in the span of just ten months.

When asked about the disappearances, White House Press Secretary Karoline Leavitt said she would inquire with the relevant agencies. ‘If true, of course, that’s definitely something I think this government and administration would deem worth looking into,’ she said during the April 15 press briefing.

Swecker, who served as a long-time FBI agent, warned that if these disappearances are connected, several foreign powers may be responsible for abducting, blackmailing, torturing and even killing key individuals to gain America’s national security secrets.

‘China, Russia, even some of our friends – Pakistan, India, Iran, North Korea – they target this type of technology,’ Swecker disclosed.

Swecker warned that enemy intelligence agencies have been attempting to derail top-secret US programs for decades, using one of two main methods: finding ways to steal the information from the US or killing those who know about the programs.

‘It’s been happening since the Cold War,’ he added. ‘Especially when nuclear technology and missile technology were first coming to the forefront. 

‘I think we’ve even seen instances where nuclear scientists have been taken out. They’ve been assassinated.’

When it comes to the first espionage tactic that may be unfolding, Swecker called the four disappearances in the US Southwest extremely ‘suspicious’.

‘If you were conjuring up a scenario here, kidnapping and trying to extract information out of someone is not unheard of,’ he told the Daily Mail.

The FBI veteran focused on the cases of retired Air Force General William Neil McCasland and aerospace engineer Monica Jacinto Reza, who were closely connected through the Air Force Research Laboratory (AFRL).

McCasland, 68 – who disappeared on February 27 after leaving his New Mexico home with only a .38-caliber revolver and no phone – supervised research projects at AFRL and allegedly knows both nuclear and UFO-related military secrets.

Reza, 60, was the first scientist to disappear in this alleged conspiracy on June 22, 2025. She vanished without a trace while hiking with two friends in California’s Angeles National Forest.

She was the director of the Materials Processing Group at NASA’s Jet Propulsion Laboratory and previously invented Mondaloy, a space-age metal used in advanced missile and rocket engines, which McCasland oversaw the funding for at AFRL.

The Daily Mail recently uncovered the disappearance of Steven Garcia, 48, who vanished without a trace on August 28, 2025. He was last seen leaving his Albuquerque, New Mexico home on foot, carrying only a handgun.

An anonymous source told the Daily Mail that Garcia was a government contractor working for the Kansas City National Security Campus (KCNSC), a major facility in Albuquerque that plays a key behind-the-scenes role in America’s national defense.

Specifically, KCNSC manufactures more than 80 percent of all the non-nuclear components that go into building the military’s nuclear weapons.

Garcia allegedly served as a property custodian at KCNSC’s New Mexico facility, giving him a top security clearance and broad access to the entire site’s nuclear secrets.

Another missing person, 54-year-old Melissa Casias, was last seen by her husband and daughter on June 26, 2025. She worked as an administrative assistant at the Los Alamos National Laboratory (LANL), which Swecker said means she likely had high-level clearance to the same sensitive nuclear information her superiors possessed. 

‘[Foreign adversaries] target individuals and try to compromise them or bribe them. So there’s a whole lot of different ways that espionage occurs,’ Swecker said.

Another former Los Alamos lab employee, Anthony Chavez, vanished without a trace in May 2025.

Police told the Daily Mail that Chavez, 79, had retired in 2017. However, the lab worker disappeared in nearly the same way as Casias, walking out of his home and leaving behind his car, phone, wallet and keys.

LANL has not commented on the nature of Chavez’s work and duties at the nuclear laboratory.

Along with the four Americans still missing, four other scientists have died since July 2024, including two prominent researchers who were murdered in their own homes.

Physicist Nuno Loureiro, astrophysicist Carl Grillmair and pharmaceutical researcher Jason Thomas were all found dead.

Loureiro was a key scientist at the Massachusetts Institute of Technology and was reportedly on the brink of revolutionizing the energy sector using nuclear fusion before being shot to death in his Massachusetts home on December 15, 2025.

Authorities said the gunman was Claudio Neves Valente, a former classmate of Loureiro’s in Portugal, who was also accused of carrying out the mass shooting at Brown University on December 13.

Grillmair, 67, had worked on infrared space telescopes that use the same technology as military systems for tracking satellites and hypersonic missiles. He was fatally shot while standing on his front porch in California on February 16.

The Los Angeles County Sheriff’s Department named Freddy Snyder, 29, as a person of interest in Grillmair’s homicide case and later charged the man with murder, carjacking and burglary.

However, police did not release a motive in the alleged homicide, and it was unclear if the two men knew one another or whether the shooting was targeted.

Thomas’s remains were found in a Wakefield, Massachusetts, lake on March 17 – three months after the drug researcher vanished without a trace. Local police are still investigating the cause of death.

In both killings, police claimed the gunmen acted alone and have not announced any ties to foreign espionage. Investigators in the Thomas death said no foul play has been found.

Meanwhile, the circumstances surrounding the death of respected NASA scientist Frank Maiwald, who died on July 4, 2024 in Los Angeles, have not been revealed to the public or commented on by the space agency. Authorities have no record of an autopsy ever taking place. 

Maiwald, 61, had been a Technical Group Supervisor at NASA’s Jet Propulsion Laboratory and had been the lead researcher on a breakthrough that could help future space missions detect clear signs of life on other worlds.

Another mysterious case involves Michael David Hicks, a research scientist at NASA’s Jet Propulsion Laboratory, who died on July 30, 2023, at the age of 59. Officials have not publicly alleged foul play in his death.

‘This has to be fully investigated by the FBI, not different local police departments,’ Swecker told the Daily Mail, urging his former agency to treat the cases as a possible conspiracy and spy operation.

‘People who are touching on technology areas that hostile foreign intelligence services want to get their hands on… This is the type of investigation that the FBI has to take over, or at least work jointly, and look for potential connections to a hostile foreign intelligence service.’

As for the likeliest suspects that would be engaging in an espionage plot on US soil, the former FBI assistant director looked at America’s adversaries in Asia and the current conflict in the Middle East.

‘It’s an ongoing thing in the world of espionage between countries that are essentially hostile to each other,’ Swecker said.

‘China, especially, is prolific in its quest to steal technology,’ he claimed. ‘They’re not good innovators. They don’t have the scientists that we have, and they don’t have the environment for innovation. And they’re very quick to steal technology.

‘North Korea and Iran are always looking for it, but they’re more susceptible to being identified and countermeasures applied against them.

‘I’m not saying that’s what’s happening with these [cases]. But I’m saying if you look at the mosaic of what has gone on since the Cold War, there is a constant battle of espionage and counter-espionage.

‘The CIA are our spies, and the FBI are our spy catchers. This has to be a proactive investigation by the FBI.’