Tragic final text from California family who died of hyperthermia on hiking trail revealed: ‘Can you help us’

New details about the final moments before a family died of hyperthermia and dehydration on a remote hiking trail in California’s Sierra National Forest last fall have been revealed in their phone records.

Jonathan Gerrish, Ellen Chung, their one-year-old daughter Aurelia Miju Chung-Gerrish and their dog Oski were found dead on 18 August, three days after they set out for an eight-mile trek on the Hite Cove trail under harsh sun with the temperature reaching up to 109F (42C).

There was no cellphone reception where the family was discovered, but the FBI spent months poring over their cell records for information about the circumstances surrounding the deaths.

The Mariposa County Sheriff’s Office released the information on Thursday, saying it supported the coroner’s conclusion that they died due to environmental exposure.

The records show Gerrish had attempted to send multiple text messages, including one just before noon which read: “Can you help us.”

“On savage lundy trail heading back to Hites cove trail,” it continued. “No water or ver [over] heating with baby.”

Gerrish also attempted to make five phone calls, none of which were to 911.

Photos recovered from the phone showed the family set out at about 7.45am, with the final image of a creek taken at around 12pm.

Mariposa County Sheriff Jeremy Briese said the records would be the last update given by investigators on this case.

“The cell phone data results were the last thing both the family and detectives were waiting on,” he said, according to The Fresno Bee. “The extracted information confirms our initial findings. I am very proud of my team and our partner agencies for all the work they put in. Their dedication has allowed us to close this case and answer lingering questions the family had, bringing them a little peace.”

At a news conference in October, 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.

At the same briefing, the sheriff 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 in October.

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”.