California family found on hiking trail died of hyperthermia and dehydration, sheriff reveals

The California family whose bodies were found along a remote hiking trail in the Sierra National Forest back in August died from hyperthermia and dehydration, it has been revealed.

Mariposa County Sheriff Jeremy Briese announced the cause of death of Jonathan Gerrish, Ellen Chung, their one-year-old daughter Aurelia Miju Chung-Gerrish and their pet dog Oski at a press conference on Thursday afternoon.

Sheriff Briese said Mr Gerrish had plotted an eight-mile loop along the Hite Cove trail on a hiking app on 14 August.

The family then set off on the route early the following morning.

Sheriff Briese said the family walked for miles in “constant sunlight and very little shade” with temperatures reaching up to 109F (42C).

Their bodies were discovered along the Savage-Lundy Trail on 17 August just 1.6 miles from their vehicle, he said.

Mr Gerrish was found sitting on the trail with Miju and Oski next to him while Ms Chung was found slightly farther back up the trail.

There was no cellphone reception where the family was found, he said.

Sheriff Briese said one empty 85-ounce water bladder backpack was found next to the family when they were found but they had no other water containers with them at the time.

They were also carrying some snacks and bottle containing baby formula.

The family had completed most of the route when they succumbed to the heat, he said.

The sheriff also showed a video during the press conference depicting the terrain and high elevation of the trail.

The family’s babysitter had raised the alarm on 16 August when she arrived for her usual shift at their home and found they weren’t there.

She contacted their family members who reported them missing later that night.

Search and rescue teams first found the family’s vehicle before finding their bodies soon after.

For the next two months, the case baffled authorities and their cause of death remained a mystery.

“When we located the family there were no apparent causes of death,” Sheriff Briese said on Thursday.

Multiple causes of death were previously ruled out during the investigation including: suicide, being caused by a gun or other weapon, alcohol, illegal drugs, a lightning strike, extreme heat and exposure to cyanide, carbon monoxide or carbon dioxide.

One theory that remained was that they were killed by toxic algae found in the nearby water and investigators had been working with toxicology experts to determine whether the high levels of toxicity could have poisoned the family.

Sheriff Briese confirmed that these tests confirmed the presence of the toxic algae in the water but said there was “no evidence they drank any of that water”.

The area around the trail was also known to contain mines.

Sheriff Briese said one mine was also located close to where the family were found but that there was no evidence the family had come into contact with it.

He added that what happened was “an unfortunate and tragic event due to the weather”.