The mystery surrounding the murder of an astrophysicist linked to a string of strange scientist deaths and disappearances in the US has taken a new twist in court.

Carl Grillmair, 67, was shot dead outside his California home on February 16 after stepping onto his front porch around 6am local time.

The Los Angeles County Sheriff's Department charged Freddy Snyder, 29, with murder, carjacking and first-degree residential burglary, alleging he personally used a rifle during the killing.  

Snyder pleaded not guilty to all charges during his arraignment Tuesday, with a preliminary hearing scheduled for June 5. If convicted on all charges, Snyder faces a potential life sentence in prison.

The veteran California Institute of Technology (Caltech) astronomer helped contribute to the discovery of water on a distant planet, with colleagues describing his work as 'ingenious' and saying the findings could help scientists search for signs of life less than 160 light-years from Earth.

Investigators alleged Snyder armed himself with two rifles in the early morning hours of February 16 and demanded his mother's car keys inside their home. When she refused, he allegedly fired a shot into the ceiling before stealing the vehicle and driving away.

Authorities said Snyder then drove to Grillmair's nearby home, where the scientist stepped outside after noticing a vehicle in his driveway. Grillmair was allegedly shot once in the neck and died on his front porch.

Grillmair's death drew national attention after it emerged alongside a growing number of scientists tied to sensitive aerospace, defense and advanced technology programs who have been reported missing or found dead in recent years. 

Grillmair dedicated over 40 years to advancing science. According to his Caltech biography, Grillmair specialized in research involving NASA’s Spitzer Space Telescope, studying galactic structure, dark matter and stellar populations.

Los Angeles County District Attorney Nathan J Hochman said in a statement: 'Carl Grillmair was a dedicated Caltech scientist who was ruthlessly shot and killed outside his own home.

'This senseless act of violence has devastated his family and cut short a life devoted to advancing science and improving the world around him. We will ensure justice is served for this victim and his loved ones.' 

Deputies with the Los Angeles County Sheriff’s Department arrived at Grillmair’s home after receiving a 911 report of an assault involving a firearm and discovered the scientist wounded on his front porch, officials said.

Emergency crews attempted to render aid, but Grillmair was pronounced dead at the scene.

Authorities said deputies investigating the fatal shooting were simultaneously called to a nearby carjacking involving the same suspect.

Snyder was taken into custody shortly afterward and later formally arrested in connection with the killing, investigators said.

Prosecutors charged Snyder on February 18 with murder, alleging he intentionally fired a rifle and caused Grillmair’s death. 

He also faces charges of carjacking and first-degree residential burglary tied to separate incidents, authorities say occurred in December and February.

Court and jail records show Snyder had previously been arrested in December on suspicion of carrying a loaded firearm in a vehicle, though the charge was later dismissed for unclear reasons.

A longtime colleague told the Los Angeles Times that Grillmair chose to live in the California desert because the dark skies offered ideal conditions for astronomy, eventually building a private observatory at his home.

While Grillmair's alleged killer had been arrested, no motive was given, leaving some of the public to deem the death mysterious. 

The murder entered the spotlight following the discovery of the disappearance and deaths of other scientists with ties to NASA, nuclear research, aerospace programs and classified projects.

This disturbing pattern emerged after retired Air Force General William Neil McCasland vanished on February 28.

The strange circumstances surrounding the general's disappearance were almost identical to four other missing-person cases taking place between May and August 2025 in the Southwest.

Concerningly, all four have been tied to McCasland through his work overseeing the Air Force Research Lab (AFRL), based at Wright-Patterson Air Force Base, which has been rumored to study extraterrestrial technology since the 1947 Roswell UFO crash.

While at Wright-Patterson, McCasland oversaw and reportedly approved the funding for scientist Monica Jacinto Reza's work on a space-age metal for rocket engines called Mondaloy.

Reza, 60, disappeared while hiking with friends in California on June 22 last year. She had just become the director of the Materials Processing Group at NASA's Jet Propulsion Laboratory.

The three other disappearances all involved workers at some of America's most important nuclear facilities, and all three were last seen walking out of their homes without their phones or keys, just like McCasland.

Steven Garcia, 48, vanished without a trace on August 28 last year. He was last seen leaving his Albuquerque, New Mexico, home on foot, carrying only a handgun.

An anonymous source told the Daily Mail that Garcia was a government contractor working for the Kansas City National Security Campus (KCNSC), a major facility in Albuquerque that manufactures more than 80 percent of all the non-nuclear components that go into building the military's nuclear weapons.

Anthony Chavez and Melissa Casias both worked at the Los Alamos National Laboratory (LANL), one of the nation's most important nuclear research sites.

Chavez, 79, worked at the lab until his retirement in 2017, although his role there has not been made clear. Casias, 54, was an active administrative assistant at the facility and is believed to have had top security clearance.

All three were last seen leaving their homes in New Mexico on foot, leaving behind their cars, keys, wallets and phones before disappearing without a trace. Police have not had any updates in the cases since last year.

In addition to the string of disappearances, five scientists in key areas of research have died over the last few years.

Amy Eskridge was just 34 years old when she allegedly died from a self-inflicted gunshot to the head in Huntsville, Alabama, on June 11, 2022. However, neither the police nor the medical examiners have publicly released any details of an investigation ever taking place.

Before her death, she was openly researching and trying to develop anti-gravity technology, a way to control or cancel out gravity, which could revolutionize space travel and energy production.

Nuclear physicist Nuno Loureiro and astrophysicist Carl Grillmair were both shot to death in their homes in recent months.

Independent investigators have noted that Loureiro's revolutionary work in nuclear fusion may have made him a target of a greater conspiracy against US scientists, as his work may one day upend the energy industry.

Last year, Claudio Neves Valente was identified by Boston authorities as a suspect in the shooting of Loureiro, as well as two Brown University students, Mukhammad Aziz Umurzokov and Ella Cook.

After eluding police for days, Valente, 48, died by suicide in a storage unit in Salem, New Hampshire, on December 16.

Meanwhile, NASA scientists Michael David Hicks and Frank Maiwald, who also worked at the Jet Propulsion Lab, died from unknown circumstances at an early age.

Maiwald, 61, was the lead researcher on a breakthrough that could help future space missions detect clear signs of life on other worlds just 13 months before he died in 2024.

Hicks, whose death came just a year after leaving JPL at age 59, had been involved with the DART Project, NASA’s test to see if humans could deflect dangerous asteroids away from Earth.

In another mysterious incident, Jason Thomas, a pharmaceutical researcher testing cancer treatments at Novartis, was found dead in a Massachusetts lake on

March 17, after disappearing without a trace in December. Local police have claimed there was no foul play suspected.