The Northern California family of three found dead on a remote Sierra National Forest hiking trail over the summer died of extreme heat as temperatures soared to 109 degrees, authorities said this week.
Jonathan Gerrish, his wife Ellen Chung and their 1-year-old daughter Aurelia “Miju” Chung-Gerris died of hyperthermia — which occurs when a person’s body temperature is dangerously high after exposure to hot, humid weather, Mariposa County Sheriff Jeremy Briese said Thursday.
Their dog, Oski — an 8-year-old Australian shepherd and Akita mix — also died on the trail. Oski’s exact cause of death is unclear, but Briese said evidence indicates the dog was “possibly suffering from heat-related issues.”
“This is an unfortunate and tragic event due to the weather,” Briese said.
Multiple other factors — including murder, lightning strikes, poisoning, illegal drugs and suicide — were investigated and ruled out.
The family set out around 8 a.m. Aug. 15, when temperatures sat around 74 degrees, according to Briese.
But by the time they reached the steep uphill portion of the hike known as the Savage Lundy Trail, temperatures reached a scorching 109 degrees.
The family’s relatives reported them missing — and authorities found them two days later.
Gerrish, 45, was an experienced hiker who used an app on his phone to plot a route along the Hite Cove Trail, a loop that runs about 8 miles, hugging the south fork of the Merced River, Briese said.
But shade was minimal on the trail, where many of the trees had been destroyed in a wildfire three years ago.
The family had an empty 85-ounce water container with them, investigators found.
Tests of the water in the Merced River indicated it was contaminated with Anatoxin A, a lethal toxin produced by blue-green algae — prompting the Bureau of Land Management to close campgrounds and recreation areas along a 28-mile swath of the river.
But Briese said Thursday there is no indication that the family drank any of the water.
The FBI is “making good progress” in attempting to unlock one of the adults’ cell phones, in an attempt to find “more answers about that day,” Briese said.
Unnamed family members issued a statement following the determination of the family’s cause of death.
“Some questions have been answered, and we will use this information as a way of helping us come to terms with the situation,” the relatives said in the statement, read by Kristie Mitchell, the public information officer for the sheriff’s office. “Our hearts will never forget the beautiful lives of Jonathan, Ellen, Miju, and, of course, Oski. They will remain with us wherever we go.”
With Post wires