Mariposa family died from hyperthermia along Sierra forest trail near Yosemite, sheriff says
CORRECTION: The Mariposa County Sheriff’s Office said the family died from hyperthermia. This story initially reported the cause of death as hypothermia.
Hyperthermia and probable dehydration are what killed a Mariposa family mysteriously found dead two months ago along a remote Sierra National Forest Trail, the Mariposa County Sheriff’s Office announced Thursday.
The office said the news conference would be its “final investigative update” about the deaths of Jonathan Gerrish, Ellen Chung, their 1-year-old daughter, Aurelia “Miju” Chung-Gerrish, and family dog, Oski, an 8-year-old Aussie/Akita mix.
The dog’s death remains undetermined, but investigators believe it was likely also heat-related, Mariposa County Sheriff Jeremy Briese said.
Hyperthermia occurs when body temperature is abnormally high and is heatstroke in its most severe form, Briese said. Investigators said weather conditions rose dramatically, from the mid-70s to over 100 degrees, on Sunday, Aug. 15, when the family was believed to be hiking in the Hites Cove area of Devil’s Gulch, southwest of Yosemite National Park.
They were found dead two days later, on Tuesday, Aug. 17, by a search and rescue team. They were located together on the Savage-Lundy Trail just 1.6 miles from their truck at a nearby trailhead.
Briese said they were nearly done with an 8-mile loop hike when they died, and were on a steep, exposed uphill ascent with little shade because of the Ferguson Fire that burned the area in 2018. He said temperatures were between 107 and 109 degrees in that area that afternoon. Briese said he didn’t know if the family died at different times or around the same time.
Briese said the official cause of death was determined based on the autopsy, investigation, and many toxicology results.
These are the first heat-related deaths that Briese said he’s heard of in Mariposa County, at least over his 20 years with the sheriff’s office.
Gerrish and Chung family say they will always ask, ‘Why?’
Kristie Mitchell, the public information officer for the Mariposa County Sheriff’s Office, read a statement from the Gerrish-Chung family at the news conference.
The family said the pain of losing family members, especially a baby, was exacerbated by the lack of knowledge around the family’s death. They also expressed “heartfelt” thanks to the sheriff’s office and other investigative partners for their work on the case.
“They felt our pain, shared the distress of our loss, and responded with sympathy, empathy, and total dedication trying to find some answers for us,” the family said in the statement.
“Some questions have been answered, and we will use this information as a way of helping us come to terms with the situation,” the family continued. “However, the question of ‘Why?’ can never be answered and will remain with us.”
The family said the memory of their loved ones’ beautiful lives will always be with them.
“In the future, when we sit beneath the trees, listening to the wind soaring through the branches, we will hear them, and we will remember.”
Toxic river algae water and mines ruled out in case
The Mariposa County Sheriff’s Office said the family was reported missing late Monday night, Aug. 16, after a babysitter showed up for a regularly-scheduled shift and found no one home.
Investigators found an 85-ounce CamelBak-type backpack with the family, along with a small amount of baby formula in a bottle, some snacks, car keys, a child carrier backpack, and a cellphone, which the FBI is still looking at for more clues. Briese said there is no cell service in the area where they were found. He said they were wearing basic hiking attire, with shorts and tank-tops, but didn’t have hats.
They were not carrying a water filtration system. Briese said he’s not sure if the water in the CamelBak was bottled but that it appeared to be clean or tap water.
“There was a small amount of residue (in the CamelBak), but basically empty,” Briese said. “There was a minute amount that we were able to collect a sample for testing.”
Part of the family’s hike ran parallel to the south fork of the Merced River, which has a known toxic algal bloom. They were found dead about two miles from that river, Briese said.
“We do not have any evidence that Jonathan, Ellen, or Miju ingested any of that (river) water,” Briese said, “and we also know that there has not been any recorded deaths of humans connected to anatoxin-a. But we do know that anatoxin-a is and can be deadly to animals.”
Anatoxin-a, sometimes called “very fast death factor,” was found in the south fork of the Merced River, near where the family was found dead. Despite its presence, the State Water Resources Control Board early last month recommended only a “caution” advisory in that area, which is two tiers below the state’s most serious danger advisory.
Briese said six different laboratories tested water in the area, and it was determined the family didn’t ingest anything fatally toxic from the water. Anatoxin-a was not found in the water bottle sample, he said.
Old mines in the area were among the early concerns in the investigation.
“One mine was located over two miles from where the family was located,” Briese said, “and our staff, along with the California Highway Patrol, H-40 (helicopter), searched that area and found no evidence that the family located or accessed the mine.”
Sierra National Forest previously closed large portions of its forest through Oct. 29, citing “unknown hazards found in and near the Savage Lundy Trail” where the family was found dead. The order remained in effect Thursday. Briese said he didn’t know if it would be lifted early.
Briese didn’t share any other hazards in the area for hikers and encouraged residents to be prepared before heading out on a hike.
“The community is resilient, the community is safe,” he said, “and this is, again, an unfortunate and tragic event due to the weather.”
Huge investigation with many law enforcement partners
The sheriff’s office previously said the family was not killed by a gun “or any other type of weapon,” a lightning strike, suicide, or “chemical hazards” along a trail, including carbon monoxide, carbon dioxide, cyanide exposure, illegal drugs, or alcohol, and that all other causes of death remained possible.
“Many toxicology reports have been completed,” the sheriff’s office said Sept. 30, “however, we are still pending a few key results.”
Briese said Thursday that no prescription drugs were found in their system, either.
The investigation involved a long list of partners, including toxicologists, environmental specialists, law enforcement agencies, and land managers on the local, state, and national levels.
“Our office received an overwhelming number of tips, suggestions, and investigative requests that were all reviewed and taken into consideration,” Briese said. “We’re confident of our findings, and our investigation supports the findings for the pathologist and coroner’s office.”
Briese said sharing their findings with the Gerrish-Chung family helped them and investigators.
“This is a real tragedy,” he said, “and it affects us as well, so it was a good time to connect and be able to grieve.”
This story was originally published October 21, 2021 at 2:04 PM with the headline "Mariposa family died from hyperthermia along Sierra forest trail near Yosemite, sheriff says."
