Nearly a year after her disappearance, the autopsy of Melissa Casillas has been released, revealing a gunshot wound to the head but leaving the manner of death shrouded in uncertainty. The medical examiner has ruled her death “undetermined,” refusing to classify it as homicide, suicide, or accident, despite a bullet passing through her skull and a firearm found nearby.
Melissa Casillas, a 54-year-old administrative assistant at Los Alamos National Laboratory, vanished in June 2025. Her husband, Marcus, also a lab employee, told investigators she dropped him off at work that morning, then returned home after forgetting her badge. Her daughter saw her at 7:45 a.
m. Later that day, family found her purse, ID, and cell phones still at the house.
Two of her phones had been factory reset, wiped clean of data. That same afternoon, a family acquaintance spotted Melissa walking eastbound on State Road 518, captured on security video. It was the last confirmed sighting.
For nearly a year, no trace of her was found despite extensive searches by family, volunteers, and law enforcement.
On May 28, 2026, a hiker discovered human remains in the McGaffy Ridge area of Carson National Forest, a remote, desolate region. A handgun lay alongside the skeletonized remains. The Office of the Medical Investigator positively identified the body as Melissa Casillas using dental records.
The location offered a view of the surrounding mountains, but raised immediate questions.
The autopsy report, obtained by Law and Crime, details projectile trauma to the cranium. The bullet entered the cranial base from the right side, damaging the left anterior side of C1 and the left foramen magnum. It traveled from right to left, inferior to superior, and slightly posterior to anterior, exiting through the squamous portion of the temporal bone.
Former FBI special agent Daniel Bruner analyzed the trajectory, noting it is an awkward path for a self-inflicted wound. “This right here is not a normal path for a self-inflicted gunshot wound,” Bruner said. “I would be leaning in the direction of homicide because of the direction of travel, the entry, the movement of the bullet.”
The report also notes that the left hand and left foot were missing, with the left tibia, fibula, shoe, and sock found about 20 feet away. The remains showed signs of predation. Bruner said animal scavenging is the most logical explanation for the missing parts, but the loss of tissue also prevented testing for gunshot residue on her hands.
The medical examiner cited advanced decomposition and a “paucity of information” as reasons for the undetermined ruling. “Given the state of the body’s advanced decomposition and paucity of information available at the time of the writing of this report regarding the circumstances of her death, the manner of death is certified as undetermined,” the report states.
The Casillas family has rejected that conclusion. In a statement, Melissa’s paternal side said, “We want to make something very clear. The Mandragon family and Melissa’s closest friends do not believe Melissa took her own life.
Those who knew and loved Melissa know how deeply she loved her daughter. Melissa would not willingly leave her daughter behind.”
The family hired their own search team, which discovered evidence that law enforcement apparently missed. According to the autopsy report, on June 24, 2026, the medical examiner received an infant body bag containing additional remains from a private detective who had searched the scene after the recovery team left.
Those remains included shafts of the left radius and ulna, shafts of two metacarpals, and small bone fragments. On July 2, 2026, cervical vertebrae two through five and much of the left foot were also turned over. The family’s attorney said shredded paper, hair, and clothing with possible blood were also found.
Bruner expressed deep concern over the missed evidence. “That is incredibly disturbing,” he said. “To find that you are finding additional physical evidence, possibly body parts, at a possible murder scene is unacceptable.
The initial search team should have taken their time, set up a perimeter, and gone over everything with a fine-tooth comb.”
The handgun found near the body was reportedly registered to Melissa’s husband, Marcus Casillas, according to the Crime Junkie podcast. Los Angeles magazine reached out to authorities to confirm that detail. The autopsy also noted a preliminary toxicology screening suggesting the possible presence of marijuana in brain tissue, though it was not confirmed with more specific testing.
Bruner emphasized that the lack of clear answers forces law enforcement to treat the case as a potential homicide. “Without those clear answers, the law enforcement entities cannot say definitively that it was suicide. They have to go in the assumption this is possibly a homicide, and that’s absolutely the way they should be moving forward.”
The investigation remains open, but the family’s trust in authorities has been shaken. The discovery of shredded paper with handwriting that Melissa’s sister recognized adds another layer of mystery. The phones being factory reset also raises red flags.
“Why would her cell phone be erased?” Bruner asked. “There’s more to it.”
Melissa Casillas was an experienced hiker and hunter, but the remote location of her remains—far from the road where she was last seen—has fueled speculation. Some theorize she was killed elsewhere and her body transported. Bruner said that is possible but unlikely given the difficulty of carrying a body to such a remote spot.
The case has drawn national attention, partly because of Melissa’s connection to Los Alamos National Laboratory, one of the world’s most sensitive national security labs. The lab has not commented on the investigation. New Mexico State Police have not released additional details about potential suspects or motives.
As the family continues to push for answers, the medical examiner’s ruling leaves a chilling ambiguity. A gunshot wound, a firearm, a missing scientist, and a manner of death that remains officially unknown. The autopsy report has opened a new chapter, but the final page is far from written.
