A Northern California family who were found dead in August died from heat and dehydration during their hike in Sierra National Forest, officials said Thursday.
Mariposa County Sheriff Jeremy Briese said at a news conference that investigators considered environmental and other factors before they determined that exposure to the elements killed the family of three. Briese said the cause of death was "hyperthermia and probable dehydration."
John Gerrish, Ellen Chung, their 1-year-old daughter, Miju, and their dog were all found dead Aug. 17 more than a mile from their car off Savage Lundy Trail with "no apparent causes of death," Briese said. Investigators combed the area, searched abandoned mines for signs of entrance by the family and investigated possible exposure to toxic gases but found none.
Investigators did not determine the dog's cause of death.
"Heat-related deaths are extremely difficult to investigate," Briese said, adding that investigators spent time combing the rugged mountainside terrain and determined the family of three and their dog climbed in midday triple-digit heat.
"There was one 85-ounce water bladder backpack located with the family. This water bladder was empty, and no other water containers, no other water filtration systems, were located amongst the family," Briese said.
Authorities investigated whether they may have ingested river water contaminated with anatoxin-A, an element of algae that can be toxic to humans and animals, but found no evidence that they drank any.
The family was found in an area known as Devil’s Gulch in the South Fork of the Merced River in August after a friend reported them as missing. Briese said at the time that there was no obvious cause of death and that the area had unreliable cell reception.
The sheriff’s department said it worked to rule out a number of possible causes, including a lightning strike, carbon monoxide, carbon dioxide, cyanide exposure, illegal drugs, alcohol or suicide.
The Bureau of Land Management shut down campgrounds and recreation areas along the river, between the towns of Briceburg and Bagby, after the deaths.