New Mexico State Police have confirmed that a handgun discovered near the skeletal remains of missing nuclear laboratory worker Melissa Casias was purchased by her husband, Mark Casias, who is an avid hunter. The remains of the 53-year-old were found on May 28 in a remote area of Carson National Forest, approximately six miles from her Taos home. This revelation comes nearly one year after Casias vanished without a trace.
An autopsy revealed that Casias had been shot in the head around the time of her death, but medical investigators could not definitively determine whether she died by suicide or if foul play was involved. State Police have stated the investigation remains active, but have not disclosed if suspects have been named or if Mark Casias has been interviewed regarding the weapon found near his wife's body, or if the gun was fired.
Casias was last seen leaving her home on foot on June 26, 2025. She had reportedly returned home because she had forgotten her security badge, delivered lunch to her daughter's workplace, and was last seen walking alone along State Road 518 at approximately 2:20 p.m. Both Melissa and her husband, Mark Casias, were non-scientific staff at Los Alamos National Laboratory.
Melissa Casias's family and friends have expressed strong disbelief that she would have taken her own life. Her parents and siblings, along with a hired attorney, raised concerns about the initial handling of the investigation, claiming that evidence such as bloody clothing, bones, hair, and a tobacco pouch were found by volunteers in the area where her body was discovered, evidence they allege was overlooked by police. The family attorney stated that Casias was not known to use tobacco.
In a Facebook post on August 7, Casias's relatives wrote, "We want to make something very clear: The Mondragon family AND Melissa's closest friends do not believe Melissa took her own life!" They added that those who knew her understood her deep love for her daughter and that she would not willingly leave her behind or end her own life. The family maintains that the condition and circumstances of her remains discovery have only raised further questions.
Casias's daughter, Sierra, who is believed to be the last family member to see her alive, has stated she is not connected to her relatives' private investigation and has pushed back against claims of foul play. In a statement, she noted that the medical examiner's ruling of "undetermined" does not imply responsibility for her mother's death and should not be used to create an unsubstantiated narrative.
Sierra Casias also indicated that her mother was carrying a backpack when she disappeared, which was found near her body. A gun holster was located inside the backpack. A bottle of alcohol and potential notes were also found in the vicinity. She added that evidence from the scene has undergone additional forensic examination for which they are awaiting results. Sierra Casias had previously stated that her mother did not own any handguns and did not carry a weapon to her job at the nuclear lab.
Concerns have been amplified by the autopsy findings, which revealed a large exit wound on the left side of Casias's skull. Diagrams of the death suggest a bullet may have traveled through the right side of her cranial base, near where the jaw meets the head, damaging the C1 vertebra before exiting the left temple. The bullet has not been recovered.
An anonymous law enforcement source suggested to the Daily Mail that the angle required for a self-inflicted gunshot to the head in this manner would be highly implausible, indicating a potential for murder. However, New Mexico authorities officially stated that the decomposition of Casias's body was too severe to determine the cause of death or the proximity of the gun to her head.
Former FBI agents have also questioned the circumstances surrounding Casias's disappearance, including the fact that both of her phones were left at her home and had been wiped clean of all data on the day she vanished. Former FBI agent Ben Hansen expressed that the details shared are highly suspicious, leaning towards an 80 percent probability of foul play. He speculated about potential outside influence, including foreign adversary involvement, or that Casias may have been enticed into a situation believing she would return.
Casias's work at Los Alamos National Laboratory has also fueled speculation about a larger plot to steal classified government data. Her disappearance has been linked to other missing persons cases in the Southwest involving former nuclear lab employees, NASA scientists, and military personnel, prompting the White House to direct the FBI to investigate potential ties between these incidents. However, according to the family's attorney, there has been no visible indication that the FBI is investigating Casias's death.