President Donald Trump has been briefed on the 10 U.S. scientists that have either disappeared or died in the past few years, calling the situation "pretty serious stuff."
Trump issued the warning a day after White House Press Secretary Karoline Leavitt said the administration would look into the cases. The remarks come amid growing scrutiny and unanswered questions surrounding multiple scientists whose disappearances or deaths have drawn national attention and fueled concern within the scientific community. Officials have not confirmed any links between the cases, but Trump’s comments signal heightened White House awareness as investigators work to determine whether the incidents are isolated or part of a broader threat.
Trump added that he hoped the disappearances and deaths were "coincidence," but that White House officials would know more in the next week and a half.
"Some of them were very important people, and we're going to look at it over the next short period," Trump told reporters on Thursday.
When reached on Thursday afternoon, the White House referred Newsweek to the president's comments.
Fox News shared a clip of the president's words about the topic on Thursday.
While there has been no established link between the cases, the clustering has prompted growing public scrutiny and calls for closer examination. Leavitt said this week that the Trump administration would seek answers after reports highlighted a wave of scientists who have either died or vanished since 2023.
Below is the list of workers with ties to advanced research who have disappeared or died since 2023:
- Steven Garcia—Government contractor at the Kansas City National Security Campus in Albuquerque.
Missing since: August 28, 2025. - William "Neil" McCasland—Retired U.S. Air Force major general.
Missing since: February 27, 2026. - Anthony Chavez—Former employee at Los Alamos National Laboratory.
Missing since: May 8, 2025. - Melissa Casias—Administrative worker at Los Alamos National Laboratory.
Missing since: June 26, 2025. - Monica Reza—Director of Materials Processing at NASA’s Jet Propulsion Laboratory.
Missing since: June 22, 2025. - Nuno Loureiro—Director of MIT’s Plasma Science and Fusion Center.
Died: December 16, 2025 (after being shot on December 15, 2025). - Carl Grillmair—Caltech astrophysicist who worked on NASA’s NEOWISE and NEO Surveyor missions.
Died: February 16, 2026. - Michael David Hicks—Research scientist at NASA’s Jet Propulsion Laboratory; worked on the DART Project and Deep Space 1 mission.
Died: July 30, 2023. - Frank Maiwald—Principal researcher at NASA’s Jet Propulsion Laboratory.
Died: July 4, 2024. - Jason Thomas—Pharmaceutical researcher at Novartis working on cancer treatments.
Died: March 17, 2026.
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Update 4/16/2026, 5 p.m. ET: This article was updated to include additional information.
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