Cause of Death of California Family of 3 and Their Dog on Hiking Trail Was Hyperthermia, Officials Say
“Heat-related deaths are extremely difficult to investigate,” Sheriff Briese said describing their deaths as “horrible,” and “unfortunate.”
The California couple, their 1-year-old daughter, and family dog, that were found dead on a hiking trail in the picturesque Sierra National Forest, died of hyperthermia and possible dehydration, the Mariposa County Sheriff’s Office announced at a press conference on Thursday.
Triple-digit temperatures that day that soared to nearly 110 degrees, the absence of shade and lack of water was determined to be the cause of the tragic deaths of John Gerrish, Ellen Chung, and their baby daughter, Aurelia “Miju,” along with the family’s dog, Oksi, an 8-year-old Aussie-Akita mix, Mariposa County Sheriff Jeremy Briese said.
On Aug. 17, the family's remains were found about 1.6 miles from their vehicle. The trail they were hiking was steep and temperatures were warmer than hikers would likely expect unless they were familiar with it, the sheriff said. Temperatures had ranged from 107 to 109 degrees on the afternoon they had been hiking. He also said the family had no cellphone service to call for help.
During the press briefing, Briese gave a detailed timeline of the events and showed a map and a short video of the trail area, specifically the Savage Lundy portion, of the current terrain.
“Jonathan, his wife, Ellen, their 1-year-old daughter, Miju, who was riding in a backpack-style child carrier, and the family dog Oski, left on foot from the Hites Cove Road / Trailhead. The family walked 2.2 miles down Hites Cove Road/Trail to the US Forest Service Trail 20E01.4, the elevation at the trail intersection is approximately 1,930 feet and the approximate temperatures were between 92-99 degrees,” Briese said.
He said the section of the Savage Lundy trail is a south/southeast facing slope that gets constant sunlight and gets very little shade due to the Ferguson Fire of 2018. Between the hours of 12:50 p.m. – 2:50 p.m, the temperatures ranged between 107-109 degrees and cooled slightly to 105 degrees from 4:50 p.m. to 8:50 p.m.
When search teams found the family around 9:30 a.m., their 85-ounce CamelBak water bladder they had been carrying was empty and there had been no other water containers or water filtration systems located on them, officials said.
“Heat-related deaths are extremely difficult to investigate,” Briese said, describing their deaths as “horrible,” and “unfortunate.”
“It is rare. This is the first hyperthermia-type death as long as I have worked here for 20 years. We don’t see them all the time, but there are desert areas in California where these types of tragedies happen,” he said.
During the two-month investigation, the Mariposa County Sheriff’s Department partnered with more than 30 local, state and federal agencies. A preliminary autopsy revealed that there had been no signs of trauma or foul play, and the family’s toxicology results had come back with negative results, the sheriff said.
Six separate laboratories assisted in testing water samples taken from several locations along the South Fork of the Merced River, and they tested positive for Anatoxin A, according to Briese.
"We do not have any evidence indicating that Jonathan, Ellen or Miju ingested any of that water. We also know that there has been no recorded death in humans connected with Anatoxin A; we do know that can be deadly to animals," Briese said.
During the investigation, hazmat teams were on site after officials from Sierra National Forest (SNF) had posted signs warning of toxic algae present in the area. Days after the family had been reported missing, the U.S. Forest Service closed trails and recreation sites near where their bodies were found.
Investigators also checked some nearby mine shafts. The sheriff confirmed that the family did not go into the site.
“From the beginning, the Gerrish and Chung families have been our top priority,” the sheriff said. "We are confident in our findings and our investigation supports the findings from the Pathologist / Coroner’s office and assisting agencies."
When the story first broke in August, the case had perplexed authorities, who described it as “nothing the agency has seen before."
“It is not every day you come across a scene of an entire family and their dog that are seemingly healthy,” Mariposa County spokesperson Kristie Mitchell said.
Mitchell told Inside Edition Digital that the family had moved to the Mariposa area from the San Francisco area within the last 16 months and did not live far from the trailhead. They were both avid hikers and hiked many trails in that area, which is known for its stunning wildflowers in the spring.
She explained the area where the Gerrish-Chung family ventured was a fairly popular hiking area, weather permitting.
"This time of year there aren’t as many hikers because it's hot, a little rugged, and being part of the Ferguson Fire Footprint there isn’t much shade," she said.
A family friend told KPGE that Gerrish was from the United Kingdom and Chung was from San Francisco. She said the couple owned multiple rental properties in Mariposa County and were described as “genuine people.”
Chung often shared images of her travels, her family, and their dog on Instagram.
In January, the proud mother shared a photo of Gerrish and their baby, writing, "Miss Aurelia Miju, you are so lucky the universe gave you the father you have. The amount of love he has for you is truly infinite and the way I've seen your relationship with him blossom brings tears to my eyes and warmth to my soul."
"Jonny, my one and only," she continued. "Thank you for always opening my eyes in ways I could never do for myself. The way you compliment me, makes me a better person every day, and I truly believe together there's not much we can't do. I mean look what we made."
A friend of the family said Gerrish had been a software engineer with Google in San Francisco before moving with his wife to Mariposa. He said they married two years ago, The Times of London reported.
"Everyone, friends, family, we're all bewildered and really shocked. This is a tragedy. We don't understand," the friend said.
On Thursday, before the press conference ended, the family issued a statement through the sheriff’s office sharing their gratitude to the sheriff’s office for their tireless efforts in the investigation.
"The loss of a close relative is pain almost beyond words. When that loss is multiplied by four, and one of that four is a baby of just one-year-old, then that pain is indescribable," their family wrote in the statement.
"When that pain is then further impacted by the lack of knowledge and certainty as [for] reasons for the death then the question of why, where and when and how to fill your mind all the days and all the nights," they added.
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