The FBI is leading the effort to look for possible connections into the cases of 10 missing or deceased scientists and staff who worked at sensitive nuclear or space technology laboratories, according to senior law enforcement officials.
In a statement Tuesday, the FBI confirmed it is "spearheading the effort to look for connections into the missing and deceased scientists. We are working with the Department of Energy, Department of War, and with our state and state and local law enforcement partners to find answers."
But those close to the various investigations into the disparate cases have said they see no links between them.
President Trump mentioned concerns about it last week.
"I just left a meeting on that subject, so pretty serious stuff," Mr. Trump told reporters Thursday. "Hopefully, coincidence... but some of them were very important people, and we are going to look at it."
Social media has recently lit up with theories about the disappearances and deaths, which occurred over three years and involved several researchers and other staff with ties to NASA's Jet Propulsion Laboratory and Los Alamos National Laboratory. Speculation has swirled about whether there's some kind of plot to harm U.S. nuclear or space programs.
Those involved in the various cases, however, have said that what underlies these deaths and disappearances is not a spy-thriller plot, but something more personal and tragic.
Retired Major General William Neil McCasland, 68, waslast seen at his homein Albuquerque, New Mexico, in late February. His wife, Susan McCasland Wilkerson, said in a Facebook post that it "seems quite unlikely that he was taken to extract very dated secrets from him." Her husband retired from the Air Force more than 12 years ago.
McCasland's disappearance has sparked significant online speculation about potential connections to classified military programs and UFOs because of his past role as the commander of the Air Force Research Laboratory on the Wright-Patterson Air Force Base. He's one of four current or former employees at sensitive sites who've gone missing in New Mexico over roughly the last year.
The FBI's role has evolved since last week, when a well-placed government source told CBS News on April 16 that the FBI was not investigating the disappearances and deaths as part of a suspicious pattern. Rather, the Department of Energy, which oversees NASA's Jet Propulsion Laboratory and Los Alamos National Laboratory, was looking into it.
FBI spokesman Ben Williamson described the issue last week as a "developing situation."
"The FBI is aware and providing all assistance requested," he said. "Usually what happens is we are not the lead in cases like this unless local authorities request."
FBI Director Kash Patel signaled the stepped-up involvement on Sunday, telling Fox News, "The FBI is going to be spearheading the effort, collectively with our partners at the Department of Energy and the Department of War."
In a statement to CBS News, a spokeswoman for the U.S. Department of Energy's National Nuclear Security Administration (NNSA) said the agency is paying attention to fears the cases may be linked.
"NNSA is aware of reports related to employees of our labs, plants, and sites and is looking into the matter," a spokesperson for NNSA told CBS News.
Current and former Energy Department officials acknowledged the pattern is "eyebrow raising" and that department staff and its contractors at the National Laboratories do indeed risk becoming the targets of foreign espionage. But one former staffer said they have seen no evidence of any link in these cases.
"People do just die. Strokes, heard disease, suicide, mugging, it happens," the former DOE official said.
The facilities in question combined employ more than 20,000 people, many of whom work in administrative and support roles and do not have access to secret information.
"If you attach 'nuclear weapons facility' and some sketchy sounding job title, it could conceal how mundane someone's job may be," the former DOE official said.
CBS News interviewed several energy security and law enforcement experts. None saw an obvious link between the cases.
"The deaths and missing persons cases are scattered across several years at different and only loosely affiliated organizations," said Joseph Rodgers, the deputy director of the Project on Nuclear Issues at the Center for Strategic and International Studies. "If all of the scientists were working on one project or weapons system, then I'd be more suspicious."
Scott Roecker, vice president for nuclear materials security at the Nuclear Threat Initiative, who worked on nuclear security issues for the U.S. government for more than 15 years, said the current war in Iran may factor into people's thinking.
"If you were looking at a foreign adversary, Iran might come to mind because of the Iranian nuclear scientists who have been assassinated," Roecker said.
"But we're not like Iran. We have thousands of scientists. We have a robust infrastructure. So there would be nothing strategic Iran could achieve by taking out 10 or 20 of our nuclear scientists, as tragic as the individual deaths might be," Roecker said.
Of the 10 that have garnered speculation online, one scientist disappeared while hiking in California, five died, and four people ranging from a general to an administrative staffer went missing in New Mexico over the past year. One of the five was anMIT professor killed at his doorstepby a former Portuguese classmate who was later determined to be the Brown Universitymass shooter.
New Mexico disappearances
McCasland, the retired general, left home in February without his phone, any wearable devices or his prescription glasses. All he had with him were a pair of hiking boots, his wallet, and a 38-caliber revolver.
Search and rescue teams led by the Bernalillo County Sheriff's Office and aided by state and federal agencies deployed drones and K9s in their efforts to find him. A gray U.S. Air Force sweatshirt found a mile and a quarter east of his home was picked up by investigators on March 7, but otherwise there's apparently been no trace of him.
His disappearance sparked swirling speculation online that McCasland was taken against his will in part because of his work consulting for a non-government group that was probing the government's UFO files. His wife acknowledged in the Facebook post that he had a brief association with a community of people pushing for the government to release files about UFOs, but she dismissed any notion that his disappearance was connected to that.
"Neil does not have any special knowledge about the ET bodies and debris from the Roswell crash stored at Wright-Patt," she wrote in jest in the Facebook post, referring to conspiracy theories about aliens being found in the desert.
"Though at this point with absolutely no sign of him, 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," she wrote.
The FBI has been assisting local law enforcement in the search for McCasland, according to the Bernalillo County Sheriff's Office.
"Investigators have so far uncovered no evidence of foul play," according to an official in Bernalillo County, which includes the Albuquerque metro area. The official added that the investigation is ongoing.
Albuquerque area officials are also searching for 48-year-old Steven Garcia, who disappeared last August. Garcia reportedly worked as a property custodian for the National Nuclear Security Administration's Kansas City National Security Campus in Albuquerque.
A couple of hours' drive north of Albuquerque, local police have been investigating the disappearances of two employees at Los Alamos.
Melissa Casias, 53, worked at Los Alamos for years and was last seen walking alone on a highway wearing a backpack, according to a family member who has reviewed the surveillance footage.
"Melissa was an administrative assistant and did not have high-level clearance," said her niece, Jazmin McMillen.
"I'm happy to see Melissa's case getting attention but I haven't seen any evidence linking her to any of the other cases," said McMillen, who organized family search parties and has reviewed multiple pages of police documents related to the case.
In May of last year, Anthony Chavez, 78, who had also held a job at Los Alamos, went missing. Los Alamos police are asking for the public's assistance in finding him.
A California hiker
The disappearance of an accomplished scientist in California has garnered almost as much speculation in media reports as McCasland's in New Mexico.
Monica Jacinton Reza, a 60-year-old aerospace engineer who worked on rocket engines, disappeared on June 22, 2025, while hiking in Los Angeles County.
AFacebook pagedevoted to the search for her includes pictures of her and asks for experienced hikers to help scour the rough terrain.
Murders and other deaths
Investigators say MIT ProfessorNuno Lureiro, an expert in fusion and plasma physics, was shot and killed at his home in the Boston area last December by Claudio Neves Valente, a jealous former engineering classmate who had studied in the same program with Lureiro two decades ago. Valente, who had spent time at Brown University's engineering program also carried out a mass shooting on campus thatkilled two studentsand wounded nine others just one day before he shot and killed Lureiro.
Carl Grillmair, a Caltech astrophysicist, wasshot to deathon his front porch in Los Angeles County in February. An obituary for Grillmair said he was the recipient of the 2011 NASA Exceptional Scientific Achievement Medal and numerous NASA Group Achievement Awards. A 29 year old man charged with his murder was released from prison last December by a judge using an "unnecessary prosecutions" law.
The body of Novartis researcher Jason Thomas was recovered from a Massachusetts lake last month, three months after Thomas was reported missing. His wife told NBC News he was distraught following the death of both of his parents last year.
NASA's Frank Maiwald died July 4, 2024, at 61 in Los Angeles.
Michael David Hicks, a physicist with NASA's Jet Propulsion Laboratory, died in July 2023 at the age of 59.
CBS News reviewed obituaries, statements from family members and law enforcement findings and found no links between any of the deaths.
The FBI is leading the effort to look for possible connections into the cases of 10 missing or deceased scientists and staff who worked...
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