New Mexico State Police said on Sunday that a hiker found the remains on May 28 in the McGaffey Ridge area of Carson National Forest.
Investigators said a handgun was located near the remains. Authorities, working with the New Mexico Office of the Medical Investigator (OMI), confirmed the remains as Casias.
"The cause and manner of death have not yet been determined. The remains will undergo further anthropological examination by OMI," police said.
"We confirm that the remains found in Rio Chiquito are Melissa. 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."
Casias, 53, was reported missing on June 26, 2025, after she failed to arrive at work and did not return home after visiting her daughter at work.
“Family later discovered that her personal belongings, including her purse, identification, and cell phones had been left behind, prompting concern for her welfare and a missing person investigation," according to the police.
State police said the investigation has remained active since Casias's disappearance and that the investigation will continue following the discovery of her remains.
Casias worked as an administrative assistant at Los Alamos National Laboratory, a U.S. Department of Energy facility focused on national security, scientific, and nuclear research.
Family members said Casias dropped her husband at Los Alamos National Laboratory on the day she disappeared and later returned to the Taos area. Surveillance footage and witness reports later placed her in the community before she vanished.
The discovery ends following nearly a year of public searches and appeals for information by family, volunteers, and law enforcement.
In recent months, the case has drawn wider public attention after reports linking Casias' disappearance to reports involving other missing or deceased scientists, researchers, and government employees.
President Donald Trump told reporters in April that his administration had discussed reports involving several missing or deceased individuals connected to scientific, aerospace, and national security fields, describing the matter as "pretty serious stuff."
Anyone with information about the case is asked to contact the New Mexico State Police.