The body of a woman who vanished more than a year ago has been discovered, with the grisly discovery of her remains resulting in more questions than answers.

American mum Melissa Casias was discovered by a hiker, who discovered her “skeletonised” body propped up in a seated position against a tree. She was found in a remote part of the rugged Carson National Forest with a handgun nearby and a gunshot wound to her skull.

The expansive forest spans a massive 1.5 million-acres of rugged wilderness. It also encompasses the San Juan Mountains and the Sangre de Cristo range.

But, despite being found out in the elements, her body didn’t show any signs of animal activity or disturbance, despite being left in the forest for just a few weeks short of an entire year.

Casias, 53, had argued with her husband, Mark, before dropping him off at the workplace they both shared. She allegedly claimed she’d forgotten her ID badge and had to return home.

CCTV footage shows she did indeed make it home. But she wasn’t there for long. She was last seen alive that afternoon walking east along the highway that leads out of her home city towards the woods.

Before she left, she wiped all records from her phone before walking out the door of the family home, some 70 miles northeast of Santa Fe.

She left behind her phone, keys, and wallet. While her brother claimed signs had been left behind indicating there had been a struggle in the front yard of the Casias family home, police did little to search for the missing nuclear laboratory worker. Instead, they told the family the official theory was that the 53-year-old had run off with an unknown boyfriend.

Her family have adamantly refuted claims made by police, with her parents and siblings insisting the mum of one would never leave her daughter Sierra behind by choice.

Casias was an administrative assistant at the Los Alamos National Laboratory (LANL), a scientific research facility located an hour from Taos. It was founded to house the famed Manhattan Project during the World War II, and has engaged in nuclear research since then.

That little tidbit saw Melissa’s missing person’s case skyrocket to national – and even international – attention, as wild theories began to swirl that suggested the mum-of-one’s disappearance was part of a nefarious conspiracy involving top-secret government research.

Those theories had already been dismissed by a private investigator hired by Melissa’s grief-stricken parents, Joe and Joanne Mondragon.

Arizona-based PI Thomas McNally was tasked by them to get to the bottom of Melissa’s missing person’s case. He told the Daily Mail that her disappearance should never have been lumped in with other cases involving “missing nuclear scientists”.

“It’s great that the press is getting this story out there because of the Los Alamos stuff,’ McNally said, “but it has nothing to do with [LANL]. If you want to tell the story, tell a real story.”

He added: “I want to be emphatic on this point – this is in no way, shape, or form related to her job.”

McNally does believe, however, that there was foul play involved in her death.

The grim discovery of her remains has left her heartbroken family and loved ones with more questions than answers.

McNally said: “I think them knowing that they were right exacerbates their pain that much more. I can tell you though, I think that that despair and sadness is kind of starting to turn into more of an anger and resolve to really make some people pay.”

The PI added: ‘This story will most likely continue for quite some time.’

It is understood that her devastated family is in the midst of filing a lawsuit against the New Mexico State Police for purportedly botching the case.