The daughter of Melissa Casias, an administrative assistant at Los Alamos National Laboratory whose remains were discovered in Carson National Forest, is challenging information being disseminated about her mother's disappearance and death. Sierra Casias, 19, stated on social media that false claims have been made about her mother, particularly by a private investigator hired by family members.
Melissa Casias vanished on June 26, 2025, and her skeletal remains were found on May 28, 2026, in the McGaffey Ridge area of Carson National Forest, alongside a handgun. The New Mexico State Police have confirmed the identity of the remains but are awaiting the medical examiner's official determination of the cause and time of death.
Sierra Casias has specifically refuted claims that her mother owned or carried a handgun, stating that Melissa could not legally purchase a firearm and did not possess one. She also contested allegations of marital troubles and financial disputes between her parents, Mark Casias and Melissa Casias, which were reportedly made by an investigator hired by her grandparents.
"The information being shared is largely either publicly available material presented in a misleading way or statements that are simply untrue," Sierra Casias posted in early May. She added that the investigator had made repeated accusations against her and her family while failing to contribute meaningfully to the search for her mother. The teen alleged that this individual focused on targeting her father rather than advancing the investigation.
Arizona-based investigator Thomas McNally has been reportedly working on the case for Sierra's grandparents. McNally had previously claimed that attention should be on the fact that a 53-year-old woman was missing while her husband was allegedly dating other women. He also claimed the remains showed a gunshot wound to the skull.
Sierra Casias defended her father, stating that she was present for conversations and that he did not initially have a full understanding of the family's financial situation. She described the process of uncovering and documenting financial information as ongoing and stated it was misleading to suggest her father was assigning blame for unknown circumstances.
Prior to the discovery of her mother's remains, Sierra Casias indicated she was pursuing legal action concerning the claims made against her parents. She also alleged that comments questioning the investigator's remarks or supporting her father were being deleted or blocked online, which she described as damaging to her, those who cared for her mother, and the integrity of the case.
The teen also addressed actions taken by the family after Melissa Casias' disappearance, including changing the locks on their home and discarding some of her belongings. Sierra explained that their home had been previously broken into by her ex-boyfriend, and disputes with other family members prompted them to secure the residence. She also stated that her mother struggled with hoarding, leading her and her father to take excess items to a dump as the search continued.
Melissa Casias' case is one of several mysterious disappearances and deaths linked to individuals associated with U.S. nuclear facilities in recent years. These include fellow Los Alamos National Laboratory employee Anthony Chavez, government contractor Steven Garcia, and retired Air Force General William Neil McCasland. The specific connection, if any, between these cases remains under investigation.