Eight Scientists Missing or Dead: Full List of Baffling Disappearances in the U.S.

A string of eight dead and missing scientists is causing concern in the U.S., as some of the disappearances are extremely baffling. One of the missing scientists was a retired Air Force general, and some of the others had professional ties to him.

Whether there is any connection is unclear. However, the Bernalillo County Sheriff's Department in New Mexico told Newsweekthat the agency is “looking into this to see if there is any connection at all." That agency is investigating one of the disappearances, of retired Air Force General William "Neil" McCasland. Two of the missing scientists - McCasland and Monica Reza - "had a close professional connection" and disappeared within eight months of each other, according to The New York Post, which described Reza as a "rocket scientist."

Some of the deaths do not appear related due to the circumstances, however. Four of the eight suddenly disappeared.

Eric Burlison, a Missouri Republican, wrote on X: “The disappearance of multiple scientists and military personnel with ties to advanced research is deeply concerning. I’ve already requested FBI involvement, and we will keep pressing for answers.”

Fox News' Will Cain highlighted the issue, saying that the missing and dead scientists dealt with sensitive information.

Here is the full list of eight missing and dead scientists:

Monica Reza Missing: She Disappeared While Hiking in California With Friends

Monica Reza was connected to NASA’s Jet Propulsion Lab Project. “She went missing last summer while hiking in California. No trace," said Cain.

In June 2025, the Crescenta Valley Sheriff's Office posted an alert reading, "Missing Hiker – Help Us Locate Monica Reza." The flyer posted with the alert says that Reza was a resident of Los Angeles County who was last seen hiking on June 22, 2025, at 9:10 a.m. along Angeles Crest Highway. "There is concern for Ms. Reza's well-being," the flyer said, indicating that the Sheriff's Homicide Bureau was involved.

"Crescenta Valley Station is actively searching for Monica Reza, who was last seen while hiking in the Mount Waterman area," the notice said. "She was last seen wearing the clothing shown in the flyer. If you have any information about Monica’s whereabouts or may have seen her in the area, please contact our station immediately at (818) 248-3464. Please share this post to help bring Monica home safely."

There is a Facebook page devoted to finding Reza. The page documents months of search efforts, which were to no avail. According to The New York Post, Reza, 60, disappeared while "hiking with two experienced companions who were exploring the popular Mount Waterman Trail." Professionally, she was known as Monica Jacinto. "Fellow-Materials Science and Engineering at Aerojet Rocketdyne," her LinkedIn page says.

In 2017, Space News mentioned her in a news story, writing, "Aerojet Rocketdyne’s success in developing AR1, an engine designed to replace Russian-made RD-180 engines on United Launch Alliance rockets, hinges in part on its use of Mondaloy, a nickel-based superalloy invented in the 1990s by metallurgists Monica Jacinto, then working at Rocketdyne, and Dallis Hardwick from the Rockwell Science Center." The company was funded partially by NASA, according to The Post.

The Post noted that her invention of Mondaloy "brought her into the orbit of McCasland — who oversaw the Air Force group that funded research in the early 2000s into advanced materials needed for reusable space vehicles and weapons."

"Monica was hiking in the San Gabriel Wilderness area within the Angeles National Forest with two others on the trail to Waterman Mountain summit from the 6000ft Day Use Parking Lot on June 22, 2025. She became separated from the other two hikers and has not been located since," a page for her on Solve the Case says.

Retired Air Force General William McCasland Missing: He Was Involved in the UFO Community

William McCasland was a retired Air Force General. "He once oversaw funding connected to a project that also included Monica Reza," added Cain.

The case has taken a bizarre turn, with McCasland's wife debunking theories relating to UFOs.

McCasland's wife Susan McCasland Wilkerson posted a lengthy note on Facebook on March 6. In her post, she confirmed that he associated with the “UFO community,” but added, “Neil does not have any special knowledge about the ET bodies and debris from the Roswell crash stored at Wright-Patt. 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.”

The Bernalillo County Sheriff’s Office in New Mexico released a detailed timeline about the mysterious disappearance of 68-year-old William “Neil” McCasland, who was “last known to have been at or near his residence in the area of Quail Run Court NE on the morning of Friday, February 27, 2026. A Silver Alert remains in effect, and Mr. McCasland remains missing.” Some have compared McCasland’s disappearance to that of Nancy Guthrie, but there is no known connection.

McCasland is a retired U.S. Air Force general, the Sheriff wrote. McCasland was the Commander of the Air Force Research Laboratory at Wright-Patterson Air Force Base in Ohio. There, he was “responsible for managing the Air Force’s $2.2 billion science and technology program as well as additional customer-funded research and development of $2.2 billion,” his U.S. Air Force bio says.

Related:

Carl Grillmair Was Shot to Death on the Porch of His Home

Carl Grillmair was an astrophysicist at Caltech. “He worked on a NASA-supported space telescope project and infrared systems. Now, he was shot and killed at his home just two months ago," Cain said on the air.

However, according to ABC 7, a suspect was charged with killing Grillmair "after carjacking his own relative and burglarizing a home." Grillmair "was found shot to death on the porch of his home in rural Llano."

Deputies "had arrested Freddy Snyder later in the day for carjacking and soon linked him to Grillmair's shooting," ABC 7 reported, adding that the motive is not clear as it's not believed the two knew each other.

Added ABC 7: "Grillmair had worked at Caltech as an astronomer and astrophysicist for 30 years, 26 of those years with fellow scientist Sergio Fajardo-Acosta...Grillmair was renowned for his studies on the collisions of galaxies and the search for water on planets outside our solar system."

Frank Maiwald's Cause of Death Was Not Released

Frank Maiwald was a Senior Scientist at NASA’s Jet Propulsion Lab. “He died nearly two years ago but his cause of death has never been made public," added Cain.

Maiwald's obituary says, "Frank Werner Maiwald, aged 61, passed away on July 4, 2024, in Los Angeles, CA. Born on June 24, 1964, in Ratingen, Germany, Frank's journey brought immense contributions to both his personal life and professional endeavors." Daily Mail reported that an autopsy was not performed.

The obit adds, "He dedicated many years at the Jet Propulsion Laboratory (JPL), where his expertise and leadership were instrumental. Frank managed the development of the SBG-VSWIR instrument and had previously overseen the successful delivery of two instruments for the AMR-C program. His roles included serving as a technical group supervisor and contributing to various significant projects such as AMR/SWOT, COWVR, AMR/Jason 3, and HIFI."

The obituary continued, "Beyond his professional life, Frank was a devoted husband to YeonJae Maiwald, sharing a deep and loving partnership for 25 years."

Added Daily Mail: "In June 2023, just 13 months before his death, he was the lead researcher on a breakthrough that could help future space missions detect clear signs of life on other worlds, including Jupiter’s moon Europa, Saturn’s moon Enceladus, or the dwarf planet Ceres."

Melissa Casias Missing: She Was Spotted Walking on Surveillance Video

She worked at Los Alamos National Labs. “She has been missing since last summer," said Cain, adding that she had "security clearances."

In September 2025, the Taos News reported: "Two months after Melissa Casias, a 53-year-old Los Alamos National Labs employee, went missing, her disappearance has left more questions than answers. New Mexico State Police reported no breakthroughs in the investigation."

According to the Santa Fe New Mexican, "Casias had driven her husband, Mark Casias, to Los Alamos National Laboratory, where they both worked, around 6:15 a.m. June 26 but returned home to work remotely after discovering she’d forgotten her work badge."

That news site reported that, according to Casias's daughter, Casias left her vehicle, keys, work cellphone, wallet, personal cellphone, purse, and money. Her phones were "reset to factory settings." Surveillance footage emerged showing her "walking eastbound on N.M. 518," the Santa Fe New Mexican reported. It's possible she left on her own volition, the news site noted, but it's not clear.

Anthony Chavez Missing: He Disappeared 'During a Walk'

Chavez was aonnected to Los Alamos National Labs. “He disappeared during a walk. No signs. No answers," said Cain. According to Daily Mail, he worked "at the high-security nuclear lab. The facility was founded by the famed Manhattan Project during World War II. It has been tied to nuclear weapons research ever since."

Chavez "left his car locked in the driveway and did not take his wallet, keys or other personal items, which were all found inside Chavez's home," Daily Mail noted.

In May 2025, the Los Alamos Police Department shared photos of Chavez and wrote, "MISSING PERSON: On 05/08/2025 Mr. Anthony Chavez of Los Alamos was reported as a missing person. Since then, exhaustive efforts to locate him have proved unsuccessful. Mr. Chavez is not believed to be endangered, but the public is asked to help locate Mr. Chavez to ensure his safety."

The post added: "Mr. Chavez’s family and friends consider this disappearance out of character. Please contact the Los Alamos Police Department at 505-662-8222 if you have information on Mr. Chavez’s whereabouts. Photos of Mr. Chavez are attached but he is described as a 5’6” tall, 78-year-old white male, who weighs approximately 135 pounds and wears glasses."

Nuno Loureiro Was Shot & Killed When He Answered the Doorbell

"Authorities have not connected these cases, but look at the overlap," said Cain.

MIT noted, "Nuno Loureiro, a professor of nuclear science and engineering and of physics at MIT, has died. He was 47...A lauded theoretical physicist and fusion scientist, Loureiro joined MIT’s faculty in 2016. His research addressed complex problems lurking at the center of fusion vacuum chambers and at the edges of the universe."

Police believe that Loureiro was shot and killed when he answered the door at his home by Claudio Manuel Neves Valente, the suspect in the Brown University mass shooting, who later died of suicide.

Investigators "have said Loureiro and the suspect knew each other from attending the same university program in Portugal between 1995 and 2000," added CBS News.

Jason Thomas Was a Once-Missing Scientist Whose Body Was Found in a Lake

Jason Thomas was a scientist at Novartis, a Swiss pharmaceutical company, when he went missing in December 2025, according to People. According to People, he was struggling with the deaths of his parents, and no foul play is expected.

In March, Middlesex District Attorney Marian Ryan and Wakefield Chief of Police Steven Skory "confirmed that a body was recovered from Lake Quannapowitt...Preliminary information including the clothing of the victim suggests that it is the body of Jason Thomas, 45, who was reported missing to Wakefield Police on December 13, 2025."

Jason Thomas "reportedly left his home the night of December 12, 2025. When he did not return home, his wife reported him missing to Wakefield Police in the early hours of December 13," the news release says.

"Wakefield Police conducted an extensive search of the area utilizing resources from the Northeastern Massachusetts Law Enforcement Council (NEMLEC), K-9 units and drones. Today around 12:30 p.m., a detective from Wakefield Police who was searching the area of the Lake, which had previously been frozen, located what appeared to be a body in the water. Wakefield Police deployed a drone to the area to confirm. Wakefield Police and Fire responded and recovered the body."