A California couple and their 1-year-old daughter died from effects of heat stroke and possible dehydration while hiking in nearly 110-degree temperatures in the Sierra National Forest in August, a sheriff said on Thursday, solving a mystery that had confounded investigators for more than two months.
When search teams found the bodies of Jonathan Gerrish and Ellen Chung, along with that of their daughter, Miju, on the morning of Aug. 17, they had no water on them, Jeremy Briese, the Mariposa County sheriff, said during a news conference.
Sheriff Briese said that an 85-ounce CamelBak water bladder that the family had been carrying was empty. Their bodies, along with that of the family’s dog, Oski, an Aussie-Akita mix, were found about 1.6 miles from their vehicle, he said.
“Heat-related deaths are extremely difficult to investigate,” Sheriff Briese said, adding that a multitude of state and federal agencies spent weeks trying to determine what could have led to their deaths.
“From the beginning, the Gerrish and Chung families have been our top priority,” the sheriff said. “Our office received an overwhelming number of tips, suggestions and investigative requests that were all reviewed and taken into consideration. We’re confident of our findings.”
The family had completed most of an eight-mile trail loop, but was overcome by the heat, steep terrain and a lack of shade, according to the sheriff, who said that temperatures had ranged from 107 to 109 degrees on the afternoon that they had been hiking. There was no cellphone service for the family, who had been carrying snacks and baby formula, to call for help, the sheriff said.
In a statement issued on Thursday through the sheriff’s office, the family of Ms. Chung and Mr. Gerrish thanked investigators and said that losing so many loved ones was “indescribable.”
“When that pain is then further impacted by the lack of knowledge and certainty as to the reasons for their deaths, then the questions of why, of where, of when and of how, fill your mind all of the days and all of the nights,” the family said. “Some questions have been answered and we will use the information as a way of helping us come to terms with the situation, however the question ‘why’ can never be answered and will remain with us.”
The circumstances that preceded the family members’ deaths had mystified investigators, who had said that there were no signs of trauma or foul play. Initial autopsy results were inconclusive. On Thursday, Sheriff Briese said that toxicology results came back negative for drugs.
Teams in hazmat suits had swept the area for clues, and in an ominous step, the U.S. Forest Service closed trails and recreation sites near where the bodies were found in late August, 12 days after the family had first been reported missing.
Investigators even checked a mine about two miles away to see if the couple might have ventured in there — they had not, the sheriff said.
Mr. Gerrish, 45, had worked as a software engineer for Google, according to his LinkedIn profile. Most recently, he had worked for Snapchat, according to Steven Jeffe, a friend and neighbor in Mariposa, Calif. Ms. Chung, 30, was raised in Southern California, Mr. Jeffe said in an interview in September.
Warnings of potentially toxic algae blooms in the area where the family’s bodies where found fueled speculation that they may have been poisoned. On Aug. 19, the California State Water Resources Control Board urged the public to “stay away from algae and scum in the water” near the south fork of the Merced River in the Sierra National Forest.
Sheriff Briese said that water samples taken from several locations along the river tested positive for anatoxin-a, a type of toxin created naturally by blue-green algae, but that there was no evidence that the family members had ingested the water.
According to the Environmental Protection Agency, anatoxin-a has been linked to tingling, burning, numbness, drowsiness, incoherent speech, salivation in humans and respiratory paralysis leading to death in experiments involving animals.
The family was reported missing at 11 p.m. on Aug. 16, according to the Sheriff’s Office. The next day, search teams found the couple’s vehicle near one of the gates to the Sierra National Forest. Their bodies were found a short time later near Devil Gulch.