Cell phone data released Thursday by the Mariposa County Sheriff’s Office offers a glimpse into the desperate final moments of a family who died last August while hiking on a trail in the Sierra National Forest.
Jonathan Gerrish, 45, and Ellen Chung, 31, the couple’s 1-year-old daughter, Aurelia “Miju” Chung-Gerrish, and their 8-year-old Australian shepherd-akita mix, Oski, all were found dead Aug. 17 on the Savage Lundy Trail in Mariposa County.
The family’s bodies were found just about 1.6 miles from where their vehicle was parked, and their mysterious deaths fueled intense speculation for weeks until the Mariposa County Sheriff’s Office on Oct. 21 announced the cause as hyperthermia due to extreme heat and “probable dehydration.”
Mariposa County Sheriff Jeremy Briese said in a news release Thursday that the data from the couple’s cell phone, which was obtained after multiple months of working with an FBI forensic team, was the final piece of the puzzle that detectives and the victims’ family were waiting for on.
“I am very proud of my team and our partner agencies,” he said. “Their dedication has allowed us to close this case and answer lingering questions the family had, bringing them a little peace.”
Briese’s news release on Thursday said they were able to recreate the path and timeline based on GPS locations and information from the phone, including photos, an attempted text message, and phone call attempts, which supported the findings of a heat-related incident.
Gerrish and Chung took multiple photos throughout the hike beginning with the trailhead at 7:44 am, photos of the trail and South Fork Merced River that runs along it between 8 and 9:39 am, two selfie-style shots at 10 and 10: 16 am, and a final photo of the river at 10:29 am
The next image on the phone after the 10:29 am river photo was a screenshot of the location from the Trail App at 12:25 pm, the release said.
Prior to the screenshot, a text message was attempted but did not go through due to the lack of cellular service in the area to a person whose name is redacted in the news release.
“(Name redacted) can you help us,” the unsent text reportedly said. “On savage lundy trail heading back to Hites cove trail. No water or see (over) heating with baby.”
The release said there then were five calls attempted to multiple phone numbers, not including 911, between 12:09 pm and 12:36 pm — the final three were all within seconds of each other — though none were successful due to there not being any service in the area.
An empty water bladder that could hold a total of 85 ounces — roughly three quarters of a gallon — was reportedly found near the bodies of the family and dog.
In October, the Mariposa County Sheriff’s Office described the portion of the trail where the family was ultimately found dead as a “steep incline section” on a south-southeast facing slope that exposes it to constant sunlight. There was also very little shade on that section due to the 2018 Ferguson Fire, the agency said at the time.
Temperatures along the section of trail on the day the family was hiking reportedly ranged between 107 and 109 degrees from 12:50 pm to 2:50 pm, before cooling between 4:50 pm and 8:50 pm from 105 to 89 degrees.
The temperature at the trailhead, which is at a higher elevation, was reportedly 74 to 76 degrees when the family began hiking about 8 am Aug. 15.
On Aug. 16, the family was reported missing by their babysitter when she arrived for her normal shift at their Mariposa County home and was unable to locate them
After calling other family friends throughout the day, who also didn’t know where they were, the babysitter reported them missing to the Sheriff’s Office about 11 pm that night and deputies began their investigation.
A sheriff’s deputy searching the area found the family’s vehicle at the trailhead about 1:50 am Aug. 17 and requested a search-and-rescue mission to be activated.
Search-and-rescue teams arrived about 4 am Aug. 17 and began tracking down the Hites Cove Trail after locating human and animal tracks. At 8:40 am, additional teams began down the Savage Lundy Trail. A California Highway Patrol helicopter was also requested to assist.
The family and their dog were found dead about 9:30 am Aug. 17, with no apparent causes of death or signs of foul play at the scene.
Many potential causes of death were ruled out during the course of the investigation, including suicide, weapons, illegal drugs, and lightning strikes, according to a report at the time by the San Francisco Chronicle.
Toxic algae and fumes from mines known to be in the area were also discussed heavily as possible causes.
Six separate laboratories helped with testing water samples from several locations of the South Fork of the Merced River and were positive for Anatoxin A, which can be deadly to animals but has never caused any recorded deaths among humans.
There was also no evidence indicating that Gerrish, Chung or their daughter had ingested any of the river water.
A single mine was also found over two miles from where the family was located. Sheriff’s Office staff and a CHP helicopter searched the area around it and found no evidence the family had located it or been inside.
Hyperthermia is defined by the National Institutes of Health under the US Department of Health and Human Services as “an abnormally high body temperature caused by a failure of the heat-regulating mechanisms of the body to deal with the heat coming from the environment.”
Common forms of hyperthermia include heat fatigue, sudden dizziness after prolonged heat exposure, heat cramps, heat exhaustion and heat stroke.
The US Centers for Disease Control and Prevention said illnesses from extreme heat “are the deadliest weather-related health outcomes in the United States” and kill an average of about 658 people each year.
George is Digismak’s reported cum editor with 13 years of experience in Journalism