The case of a New Mexico mother who vanished without a trace last year has now been connected to the mysterious deaths and disappearances of five other key scientists and defense officials throughout the US. 

Melissa Casias has not been seen since June 26, 2025, when her family said she uncharacteristically decided to work from home, but was last spotted miles from their house walking alone without her wallet, phone or keys.

Casias, 54, was an administrative assistant at Los Alamos National Laboratory (LANL), a facility founded by the famed Manhattan Project during World War II. It has been tied to nuclear weapons research ever since.

Her disappearance takes the number of people from the scientific community potentially holding highly sensitive secrets who have gone missing or died since June 2025 to six.

Of those six, five had ties to nuclear research or missile technology and four of them can now be shown to have some type of connection to each other.

Casias went missing just four days after respected NASA scientist Monica Reza mysteriously disappeared while hiking with friends in California.

Both women had worked at facilities with ties to retired Air Force General William Neil McCasland, who also vanished near a hiking trail in Albuquerque, New Mexico, on February 27, 2026.

While her husband and daughter have previously suspected that Casias left over personal and financial struggles, former FBI Assistant Director Chris Swecker told the Daily Mail he is concerned her disappearance is part of a much larger pattern.

Swecker explained that Casias's work at LANL may have made her a target for abduction, since an administrative assistant often has access to the same sensitive files their supervisors have.

'In a classified lab, or just a high clearance lab, they would basically be in the know on what's going on,' Swecker said. 'And it wouldn't be the first time their administrative assistant has been targeted.' 

'When I look at three missing scientists in critical technology areas, what I come up with is - it has to be investigated fully by the FBI,' said Swecker, who spent 24 years with the FBI.

'They can't have these examined in isolation and compartmentalize them as individual missing person cases.'

Casias and her husband, Mark Casias, both worked at LANL at the time of her disappearance eight months ago.

According to Mark, a superintendent at the lab, Casias had the security badge needed to enter LANL with her when she dropped him off at work that morning.

However, their daughter, Sierra, told investigators that Casias visited the teen's place of work to drop off a sandwich and then claimed she was returning home after forgetting the badge.

The day went from strange to alarming when Casias's supervisor at the nuclear research lab told Mark she had never reported to work or worked from home that day.

When Casias's family returned home, they found that only her work and personal phones had been left behind and wiped clean after someone performed a factory reset on them.

Surveillance cameras last spotted Casias walking alone eastward on State Road 518, roughly three miles from her home, around 2.20pm local time. No body or any definitive evidence of her whereabouts has been found since.

According to Ashley Flowers of the Crime Junkie Podcast, Casias had allegedly lost her national security clearance at LANL due to her family's money issues that could have made her a target for blackmail.

The Daily Mail reached out to Los Alamos National Laboratory to confirm the reports and the nature of Casias's work at the nuclear testing site.

'The Lab community’s thoughts continue to be with Melissa Casias’ family. The Lab has cooperated fully on the investigation,' LANL said in a statement.

Swecker noted that the disappearances of Casias, Reza and McCasland may all be unique and unconnected, but federal officials should not take chances given the critical technology or information each was entrusted with.

'I think you have to pull out all the resources necessary to look for links and look for potential espionage activities. That's where you start,' Swecker recommended.

Swecker was particularly concerned about the disappearance of Reza, the director of the Materials Processing Group at NASA’s Jet Propulsion Laboratory and the inventor of Mondaloy, a space-age metal used in advanced missile and rocket engines. 

Reza, who vanished on June 22, 2025, was just 30ft away from two friends while they were hiking near Mount Waterman in California's Angeles National Forest.

'My antennas go up on that one, especially because you're not hiking together and someone disappears 30ft away, and you can't find a body, and you can't find a person,' Swecker told the Daily Mail.

'This really gives me pause. I would be looking at all three of them. I would dissect their lives, from high school on, and just see if there are connections here.' 

While Reza's disappearance does not connect directly to the Casias case, both women had ties to McCasland, the former commander of the Phillips Research Site at Kirtland Air Force Base in New Mexico and the Air Force Research Laboratory (AFRL) at Wright-Patterson Air Force Base in Ohio.

Reza's work to create Mondaloy was funded directly by AFRL while McCasland was overseeing the lab from 2011 to 2013.

As for Casias, McCasland previously oversaw research at Kirtland AFB from 2001 to 2004. Kirtland and LANL work closely together on national security projects, especially research involving America's nuclear capabilities.

McCasland's disappearance has also baffled investigators, as the retired Air Force general left his phone, prescription glasses and smart devices behind in his New Mexico home.

McCasland's wife, Susan, claimed that 'foul play' was not suspected in her husband's disappearance, but noted that the avid hiker and cyclist left home with only a pair of boots and his .38-caliber revolver.

The general's reported ties to secret UFO programs at Wright-Patterson Air Force Base in Ohio, and Reza's work with advanced rocket technology, have led many to claim without evidence that the pair were fleeing from parties that wished to silence them because of what they know.

Meanwhile, another scientist gunned down in an unprovoked attack at his home in California has also been connected to this growing web of suspicious events.

Astrophysicist Carl Grillmair, 67, was killed at his home on February 16, 2026, after being shot on his front porch around 6am local time.

The scientist had worked on the NEOWISE and NEO Surveyor, infrared telescope projects that track asteroids but use the same physics as military systems for tracking satellites and hypersonic missiles. 

These dual-use infrared sensors fall under AFRL's space surveillance work, which McCasland previously oversaw.

The Los Angeles County Sheriff's Department named Freddy Snyder, 29, as a person of interest in Grillmair's homicide case and later charged the man with murder, carjacking and burglary.

However, police did not release a motive in the alleged homicide, and it was unclear if the two men knew one another or whether the shooting was targeted.

Two other respected researchers in Massachusetts have been found dead since December 2025. Nuno Loureiro, who was working on breakthroughs using nuclear fusion as an energy source, was shot dead in his Brookline home last year.

Meanwhile, Jason Thomas, a pharmaceutical researcher at Novartis, was found dead in a Wakefield lake on March 17, 2026 after disappearing without a trace three months earlier.

'You can say these are all suspicious,' Swecker said, 'and these are scientists who have worked in critical technology.'

While the former FBI assistant director was not convinced there would end up being a direct tie to UFOs, as conspiracy theorists have alleged, he was gravely concerned that an organization or foreign power was targeting US citizens with knowledge of the country's national security defenses.

'Space [is] interesting, and that's sensitive technology, but I'm particularly concerned about their involvement in the missile technology,' Swecker warned.

'There are a million ways to do this type of investigation. If [the FBI] leveled their resources on it, we could get answers, and they could get answers.'