“Hyperthermia and Probable Dehydration” Confirmed as Cause of Death of Family Found Dead in Sierra National Forest, CA

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John Gerrish, Ellen Chung, and their one-year-old daughter.

A press release from the Mariposa County Sheriff’s Office has revealed the long-awaited conclusions about what had killed an active, nature-loving family and their dog in the Sierra National Forest, CA on August 15.

It has been determined that the family died of “hyperthermia and probable dehydration” while hiking on a day when temperatures hit 109ºF.

It has not been confirmed how the dog died, but it is likely also due to heat issues.

Full press release below:

This will be our final update on the Gerrish / Chung Case.

This is a tragic situation and has been a very unique case to investigate from the onset.

As of Friday October 15th, we have determined the official cause of death. Our Pathologist has completed his report based on the autopsy, our investigation, and a multitude of toxicology results. The Cause of death for Jonathan Gerrish, Ellen Chung and Aurelia “Miju” Chung-Gerrish has been determined to be Hyperthermia, and probable dehydration. Due to, Environmental exposure.

Oski the dog’s cause of death remains undetermined. Based on the condition of Oski’s remains and evidence on the scene investigators believe that Oski was possibly suffering from heat related issues. Oski was an 8 year old aussie / akita mix.

“Heat related deaths are extremely difficult to investigate, and I want to thank you all for being patient with us as we investigated this case. As I’ve mentioned the Gerrish Gung family have been our top priority as we dealt with this horrible event.”

– Sheriff Jeremy Briese

Our Office has dedicated an entire team to this case and partnered with over 30 local, state, and federal agencies.

The following timeline of events was created based off the evidence collected during the investigation:

On Saturday night, August 14th, Jonathan used an app on his phone to plot out the route of travel for the Hites Cove hike. We know while using the app, he only entered “way points” or point to point mapping, although this does not calculate the exact trail mileage or elevation changes. This was not uncommon; Jonathan used a few different trail-mapping apps and frequently took hikes.

On Sunday morning, August 15th, around 7:45am, a witness walking in the area saw the family truck heading in the direction of the Hites Cove Trail Head. At 8am the witness observed their truck parked at the trailhead and no family around. The approximate temperature in that area was 74-76 degrees and the elevation is approximately 3880ft.

Jonathan, his wife, Ellen, their 1-year-old daughter, Miju, who was riding in a backpack style child carrier, and the family dog Oski, left on foot from the Hites Cove Road / Trail head. The family walked 2.2 miles down Hites Cove Road/Trail to the US Forest Service Trail 20E01.4, the elevation at the trail intersection is approximately 1930ft and the approximate temperatures were between 92-99 degrees. They continued walking along 20E01.4 trail which parallels the South Fork of the Merced River for approximately 1.9 miles towards the Savage Lundy Trail intersection. At the Savage Lundy Trail intersection, the elevation is approximately 1800 ft and the temperature was approximately 99-103 degrees.

Jonathan, Ellen, Miju and Oski then began the steep incline section of the Savage Lundy trail. This section of the trail is a south/southeast facing slope exposing the trail to constant sunlight. There is very little shade along this section of trail due to the Ferguson Fire of 2018. The temperatures along that section of trail ranged between 107-109 degrees from 12:50pm -2:50pm cooling slightly from 4:50pm to 8:50pm from 105-89 degrees. The family hiked approximately 2 miles up the Savage Lundy trail.

On Monday, August 16th, the family babysitter arrived for her normal shift at Jonathan & Ellen’s home. The babysitter was unable to locate the family and called other family friends in an attempt to locate them. Friends continued to search and call Jonathan and Ellen throughout the day. After failed attempts to locate the family, the friends reported them missing At approximately 11pm on Monday night to our office and deputies begin their investigation.

On Tuesday, August 17th, at 1:50am, a Mariposa County Sheriff’s Deputy searching the area located the vehicle at the trailhead and requested a Search and Rescue mission be initiated.

On Tuesday, August 17th, at 4:00am, Search and Rescue teams arrived and were able to locate human and animal tracks and begin tracking down the Hite Cove Road/Trail. At 8:40am, additional teams begin down the Savage Lundy Trail. California Highway Patrol was contacted, and their helicopter H40 was requested to assist in the search.

Tuesday, August 17th, at 9:30am, Search and Rescue teams located Jonathan, Ellen, Miju and Oski approximately 1.6 miles from their vehicle on the Savage Lundy Trail deceased. It should be noted that there was only one 85 oz water bladder located with the family. This water bladder was empty and no other water containers or water filtration systems were located amongst the family.

Sheriff’s personnel located the family, there were no apparent causes of death, we requested a helicopter overflight, ensuring the safety of searchers and staff and to preserve scene integrity.

Video of portions of the Savage Lundy Trail- https://youtu.be/XoGfQBbdrEk

We were aware this trail had been posted by the Sierra National Forest for toxic algae and this area is known to have mines, which precautions were taken due to the possibility of unknown environmental hazards. Regarding the water, and if you have specific questions regarding the water sample results or other water related questions, please contact the state water board. Six separate laboratories assisted in testing water samples. The testing that was done on the water taken from several locations along the South Fork of the Merced River was positive for Anatoxin A. We do not have any evidence indicating that Jonathan, Ellen or Miju ingested any of that water. We also know that there has been no recorded death in humans connected with Anatoxin A, we do know that can be deadly to animals.

One mine was located over 2 miles from where the family was located, our staff along with the California State Highway Patrol Helicopter, H40 searched that area and found no evidence that the family located or accessed the mine.

Our office received an overwhelming number of tips, suggestions & investigative requests that were all reviewed and taken in consideration. We are confident in our findings and our investigation supports the findings from the Pathologist / Coroner’s office.

Assisting Agencies
California Department of Justice, Crime Scene Investigations
United States Forest Service (USFS), Law Enforcement
United States Forest Service (USFS), Recreation Department
United States Forest Service (USFS), Trail Maintenance
United States Department of Interior, National Park Service, Law Enforcement Special Agent
National Oceanic and Atmospheric Administration (NOAA), Meteorologist in charge, Hanford, Ca.
National Oceanic and Atmospheric Administration (NOAA), National Center for Environmental Information (NCEI)
Mariposa County Environmental Health
California Department of Public Health
California Water Board
Federal Bureau of Investigation (FBI), Weapons of Mass Destruction, Scientific Response Unit.
University of California, Davis, Veterinary Medicine
Doctor of Veterinary Medicine, Jeanette Mero
Madera County District Attorney’s Office, Cyber Investigations
Modesto Police Department, Cyber Investigations
Fresno County District Attorney’s Office, Cyber Task Force, Forensic Unit
Federal Bureau of Investigation, Cyber Investigations
California Survival School
Stanislaus County Coroner’s Office
California Animal Health and Food Safety Laboratory, Tulare, CA.
California Office of Emergency Services
California Highway Patrol, Central Division Air Operations, H40
California Office of Environmental Health Hazard Assessment (OEHHA)
Mariposa County Geographic Information Systems (GIS)
Doctors Medical Center, Modesto, CA
California Office of Emergency Service, Search and Rescue, Medical Advisor
Federal Bureau of Investigations, Cyber investigations, Headquarters, Washington D.C.
Central Valley Internet Crimes Against Children (ICAC) Task Force
Environmental Health Investigations Branch -Center for Healthy Communities
Central Valley Toxicology, Inc.
Centers of Disease Control and Prevention (CDC)-Infectious Disease Pathology Branch
Bend Genetics, LLC
Yosemite Falls Well Drilling and Pump Service
GreenWater Laboratories
UC Davis Laboratories

Statement from the Gerrish/ Chung Family:

The loss of a close relative is a pain almost beyond words. When that loss is multiplied by four and one of that four is a baby of just one years old, then the pain is 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.

Into this void came the Sheriff’s Office of Mariposa County. They have felt our pain, shared the distress of our loss, and have responded with sympathy, empathy and total dedication trying to find some answers for us. We would like to say a heartfelt thanks for their dedication and commitment. They have truly gone the extra mile. This was clearly a team effort by all concerned, from those involved in the search, in the recovery and in the investigation. However it would be invidious not to give our particular thanks and appreciation to; Sheriff Jeremy Briese, Sgt. Joe Williams, Capt. Sean Land, Undersheriff Sterling Cramer, Asst. Coroner Andrea Stewart and Sgt. Mike Charman for their extreme helpfulness and commitment.

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.

Our hearts will never forget the beautiful lives of Jonathan, Ellen, Miju and of course Oski. They will remain with us wherever we go and whatever we do. In the future, when we sit beneath the trees listening to the wind soughing through the branches we will hear them and we will remember.

Location of where the family were discovered.

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