Authorities in New Mexico have identified human remains which they recently discovered as those of a Los Alamos National Laboratory (LANL) employee who had been missing for more than a year.
In a statement released over the weekend, state police said the remains belonged to Melissa Casias, a 53-year-old resident of Taos, New Mexico, who was last seen walking eastbound along a state highway on 26 June 2025.
A hiker had discovered Casias’s remains in the McGaffey Ridge area of the Carson national forest on 28 May 2026, according to the statement from Saturday.
“Investigators also learned that a handgun was located alongside the remains,” the state police statement said.
Casias’s case was among that of about a dozen US scientists who were linked to space, defense and nuclear research – and had either died or disappeared in recent months. Some of those deaths have been ruled suicides or are otherwise clearly explainable. But the cases collectively have fueled a surge of online speculation and conspiracy theories, gaining congressional members’ attention and even prompting Donald Trump to direct the US government to investigate, saying it was all “pretty serious stuff”.
Police said they identified Casias through coordination with the New Mexico medical investigator’s office. They said her cause and manner of death had not immediately been determined.
Meanwhile, state police added, the investigation into Casias’s prior disappearance remains ongoing.
In a July 2025 interview with NBC’s Dateline program, Casias’s husband, Mark, said he last saw her at about 6.15am on 26 June. She had dropped him off at the LANL where they both worked, a facility which helps maintain the US’s stockpile of nuclear weapons.
According to Mark, Melissa said she planned to travel to another location within the laboratory’s 40-square-mile campus for a work assignment. He said he had asked her to return the family car by 11am because he needed it later that day.
“That was pretty much the last I spoke to her that day,” Mark said of his wife, who told him she would return the car by the time he needed it.
Investigators later learned that Melissa unexpectedly returned to the family’s home in Ranchos de Taos that morning, more than an hour from LANL. Melissa’s daughter, Sierra, told Dateline she recalled asking her mother why she had come back at about 7.45am, and Melissa replied that she had forgotten her badge.
However, Mark told Dateline: “You’ve got to show your badge to get in – and … she showed her badge.”
According to Sierra, Melissa appeared normal and said she had decided to “either work from home or call out for the day”.
Later that day, Melissa delivered a sandwich to Sierra at her workplace in a local business center and briefly spoke with her between 12.50pm and 12.57pm before leaving, Dateline reported. Sierra said her mother’s behavior “wasn’t out of the ordinary”, adding: “She may have been a little more quiet, but still, nothing that caught me off guard.”
When Melissa did not return the car by 11am, Mark initially assumed she had become busy with work until Melissa’s supervisor called him to ask where she was.
“She says, ‘Is Melissa OK?’ And I’m like, ‘Yeah, she should be at work,’” Mark told Dateline. “And that’s when she told me, ‘Well, she isn’t at work.’”
According to investigators, Melissa’s last confirmed sighting was at approximately 2.18pm, when a family acquaintance saw her walking eastbound along New Mexico state highway 518 near Talpa, a small settlement in Taos county.
Investigators also said that “all belongings, including Melissa’s purse and factory reset phones, were found inside [her] home”.
Melissa’s remains were ultimately discovered about six miles from her home.
In a statement reported by the New Mexico news outlet KRQE after the recovery of her remains, Casias’s family said: “There will be more information to come but what we can tell you now is she was located in an area previously searched.
“This is a lot to process, our hearts are heavy and we fully intend to continue to pursue answers for justice.”
