MISSING: Melissa Casias
In June 2025, Melissa Casias dropped her husband off at work in Los Alamos, New Mexico… then did something nobody expected. She turned around and drove home. By that afternoon, she had vanished, leaving behind her wallet, her keys, both of her personal phones wiped to factory settings, and a family already splitting in two over what to believe. Her husband, Mark, insists she walked away on her own. Her parents and siblings are certain something far worse happened to her. Surveillance video proves she was alive walking along Highway 518 that day. But where she went next – and why – is a question that only deepens the further you pull at it.
Melissa Casias
Courtesy: Jazmin McMillen
Melissa Casias
Courtesy: Jazmin McMillen
Melissa Casias
Courtesy: Jazmin McMillen
Melissa and her husband, Mark
Source: Instagram
The Casias family. From left to right: Mark, Sierra and Melissa.
Source: Instagram
Melissa and her daughter, Sierra
Courtesy: Sierra Casias
Mark and his daughter, Sierra
Courtesy: Sierra Casias
Melissa’s sister, Trudy, and Trudy’s daughter, Jazmin
Courtesy: Jazmin McMillen
Melissa’s parents, Jose and Joanne Mondragon
Source: Facebook
Los Alamos National Laboratory
Courtesy: Sipa via AP Images
Agent Ezequiel Esquivel-Mata
Source: Audiochuck Staff
The fishtank and boots in the Casias’ house
Courtesy: New Mexico State Police
One of Melissa’s wiped phones in the office
Courtesy: New Mexico State Police
Melissa’s work badge
Courtesy: New Mexico State Police
Mark’s muddy boots
Courtesy: New Mexico State Police
Melissa on surveillance at the shopping plaza where Sierra worked.
Courtesy: New Mexico State Police
Melissa on surveillance walking along Highway 518.
Courtesy: New Mexico State Police
Rick Valerio on horseback
Courtesy: Trudy
Anthony Chavez
Source: Facebook
Monica Reza
Source: Facebook
William ‘Neil’ McCasland
Source: US Air Force
Timeline:
6:15 a.m.
Melissa drives Mark to Los Alamos National Laboratory and drops him off for work.
7:30–7:45 a.m.
Sierra wakes up and finds Melissa back home. Melissa says she forgot her work badge.
8:02 a.m.
Melissa’s older phone is factory reset.
10:45 a.m.
Mark begins calling and texting Melissa but gets no response.
12:56 p.m.
Surveillance captures Melissa arriving at the shopping plaza where Sierra works and bringing her lunch.
1:33 p.m.
Melissa texts Sierra, telling her to have Mark find another ride home.
1:38 p.m.
Melissa’s newer phone is factory reset.
Around 2:00 p.m.
Melissa’s supervisor calls Mark to report she was a no-call, no-show at work.
2:18 p.m.
Surveillance video shows Melissa walking alone along Highway 518 with a backpack.
3:30 p.m.
Sierra arrives home and finds Melissa missing. Melissa’s belongings, including phones and keys, are left behind.
5:00 p.m.
Mark calls the New Mexico State Police to report Melissa missing.
Investigators review evidence from the home, including a possible bloodstain and muddy boots.
Family organizes a search party for Melissa.
Mark tells Trudy he changed the locks on the house and installed cameras.
Mark searches along Highway 518 after reconsidering a witness sighting of Melissa.
Police interview Rick Valerio regarding a tip involving a possible body.
Los Alamos National Laboratory
Where Melissa and Mark both worked and commuted together daily. On the morning she disappeared, Melissa dropped Mark off at the lab before unexpectedly returning home.
Ranchos de Taos, New Mexico
The census-designated place where the Casias family lived.
Taos Plaza
Where Sierra worked and where Melissa is seen just before 1 p.m. Surveillance shows Melissa arriving quickly, briefly parking, and bringing Sierra lunch.
Highway 518
Approximately where surveillance footage captures Melissa walking alone along Highway 518.
Additional Information:
New Mexico State Police
If you have any information about Melissa’s disappearance, please contact New Mexico State Police at 505-425-6771.
We’d love to speak with you and see how we can support.
If you’re a law enforcement agency or family member of one of the people we mentioned in this episode, or if you’re looking for more coverage on a case, please reach out. You can email us at:
Episode Source Material
- Original reporting by Marilyn Fletcher and Nina Schutzman
- New Mexico State Police records
- Taos County District Court records
- Newsweek (4-20-2026 by Joe Edwards and Anna Skinner) Accessed 4-20-2026
FBI Investigating Missing and Dead Scientists: What We Know So Far
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