THE cause of death of a would-be UFO whistleblower set to testify in Congress has been revealed.
The development comes as the number of missing or dead space experts rises to 14 and officials launch a probe into a “possible sinister connection.”
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Would-be UFO whistleblower Matthew James Sullivan, 39, died at his home in Virginia from an accidental drug overdose, the medical examiner ruled Credit: Dignity Memorial
Sullivan died in May 2024 just months before he was due to testify before congress about a sensitive UFO program Credit: Dignity Memorial
Air Force intelligence officer Matthew James Sullivan died at home in Falls Church, Virginia, on May 12, 2024, just months before he was set to testify before Congress about secret government UFO programs.
He worked on the government’s covert legacy UFO program which he was set to expose in front of Congress in November 2024, sources told the New York Post.
The 39-year-old died of an accidental drug overdose, the Northern District Office of the Chief Medical Examiner said, the news outlet reported.
Sullivan had a deadly mix of alcohol, alprazolam (anti-anxiety medication), cyclobenzaprine (prescription muscle relaxant) and imipramine (child anxiety drug) in his body at the time of his death.
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“The manner and circumstances of his of death raise substantial questions, as he was preparing to provide testimony to Congress,” Rep. Eric Burlison said in a letter to the FBI that was obtained by The Post.
Burlison has called on director Kash Patel to launch an investigation, saying Sullivan’s death is of “grave concern” and has “implications for national security.”
Steven Garcia, 48, a government contractor with nuclear clearance disappeared on August 28, 2025 Credit: New Mexico Department of Public Safety
The FBI has said it would not comment on specific events but that 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 local law enforcement partners to find answers.”
At least 14 scientists, space engineers, and top officials all connected to high-level and secretive work with NASA, the military, and The Department of Energy, have gone missing or died since 2021.
A Republican-led House oversight committee announced on Monday that it has launched its own investigation as the reports of their deaths and disappearances “raise questions about a possible sinister connection.”
Dr. Ning Li, a a Chinese‑American physicist specializing in anti-gravity research, was hit by a car on the University of Alabama campus in 2014 and died from her injuries in 2021 Credit: Berryhill Funeral Home
Of the 14 now part of the investigation, five are missing, and nine are dead.
As well as Sullivan, the latest additions to the list are former NASA engineer Joshua LeBlanc who died last July when his Tesla smashed into a guardrail, hit trees, and burst into flames in Huntsville, Alabama.
The 29-year-old’s body was burned beyond recognition as it was revealed his car had been sitting at an airport for four hours before the crash in a trip his family say was not planned.
The scientist who worked on nuclear propulsion systems also left his phone and wallet at home.
Former NASA engineer Joshua LeBlanc died last July when his car smashed into a guardrail after being at an airport for four hours after what his family said was an unplanned trip Credit: Unknown
Amy Eskridge, 34, allegedly died from a self-inflicted gunshot to the head in Huntsville, Alabama on June 11, 2022 Credit: Facebook
Meanwhile, Dr Ning Li, a physicist specializing in anti-gravity research, was hit by a car on the University of Alabama campus in 2014 and died as a result of her injuries in July 2021.
And 48-year-old Steven Garcia disappeared on August 28, 2025, after leaving his home in Albuquerque on foot.
The government contractor with nuclear clearance reportedly took a hand gun and left his phone, keys, and wallet behind.
This is eerily similar to Anthony Chavez, 78, who is also missing and left his home on foot on May 8, 2025 without his belongings and Melissa Casias, 53, who vanished without trace on June 26, 2025.
Other disappearances include retired Air Force Major General William Neil McCasland, 68, who was last seen on February 27 near his home in Albuquerque, New Mexico, and McCasland‘s former colleague Monica Reza, 60, who vanished while hiking in California on June 22, 2025.
Caltech astrophysicist Carl Grillmair, 67, was gunned down in an unprovoked attack at his home in California on February 16, 2026 Credit: Caltech
Jason Thomas, a biologist, died after being found face down in a lake in March 2026 Credit: Wakefield Police Department
Those who have died are: NASA scientist Michael David Hicks, 59, researcher Frank Maiwald, 61, researcher Jason Thomas, 45, Astrophysicist Carl Grillmair, 67, MIT physicist Nuno Loureiro, 47, and scientist Amy Eskridge, 34.
President Donald Trump has vowed to uncover the truth, calling it “pretty serious stuff” involving “very important people.”
“I hope it’s random, but we’re going to know in the next week and a half,” Trump said.
“Pretty serious stuff, hopefully a coincidence, or whatever you want to call it.”
“No stone will be unturned,” White House press secretary Karoline Leavitt added, “in light of the recent and legitimate questions.”
Meanwhile, NASA says it is fully cooperating with investigators but said “nothing related to NASA indicates a national security threat.”
So far, no confirmed connections have been found between the deaths and disappearances.
The most high profile person to mysteriously go missing is retired Air Force general William Neil McCasland, 68 Credit: USAF
McCasland’s former colleague and Aerojet Rocketdyne material scientist Monica Reza, 60, went missing in June 2025 after also going on a hike Credit: Facebook/Help Find Monica Reza in the Angeles National Forest