Missing government worker Melissa Casias has been found dead ... with her body "skeletonized" and a gunshot wound to her skull, a report says.

According to New Mexico State Police, a hiker found "human remains" at McGaffey Ridge area of the Carson National Forest ... who authorities have ID'ed as Melissa. They also said a gun was found "alongside the remains."

NMSP hasn't announced cause or manner of death, but investigator Thomas McNally -- who'd been looking into the case for Melissa's parents -- told DailyMail that her body was "skeletonized," sitting against a tree with a gunshot wound in her skull.

McNally claims Melissa was wearing "sun-bleached clothing" and her body didn't show any signs of animal activity.

Melissa -- who worked at Los Alamos National Laboratory -- disappeared about a year ago, after she dropped her husband off at the lab, where he also worked.

Her case has made headlines because she's one of at least 10 government workers and scientists who have died or gone missing since 2023.

But McNally insists Melissa's death has "nothing to do" with those other cases, telling DailyMail ... "I want to be emphatic on this point -- this is in no way, shape, or form related to her job."

He does, however, believe there's foul play involved and says her family is filing a civil suit against NMSP ... because they believe they botched the case.

Melissa has been reported missing since June 26, 2025.

Melissa was 53.

RIP