February 17, 2022 - The Mariposa County Sheriff's Office reports after multiple months with the FBI computer/phone forensic team, the Mariposa County Sheriff’s Office has obtained details from Jonathan Gerrish’s phone.

In October of 2021 we released the cause of death determined by the Pathologist. This was based on autopsy results, our investigation, and a multitude of toxicology/scientific test results. The cause of death for Jonathan Gerrish, Ellen Chung and Aurelia “Miju” Chung-Gerrish was determined to be Hyperthermia, and probable dehydration due to, environmental exposure. Hyperthermia - The condition of having a body temperature greatly above normal.

Using the information extracted from the phone we were able to re-create the path and timeline based on the GPS locations. The details found on the phone support the findings of a heat related incident.

Phone Results

Photos: Gerrish & Chung took multiple photos throughout their hike. The following are noted on the map provided

Photo / Video 1- 7:44 A.M. – Taken just a few yards from the trail head

Photo 2- 8:00 A.M. - Trail Photo

Photo 3- 9:05 A.M. - Photo of the River

Photo 4-12 - 9:35-9:39 A.M. Photos of the river and of each other

Photo 13- 10:00 A.M. Selfie style family photo

Photo 14- 10:16 A.M. Selfie style family photo

Photo 15-16 -10:29 A.M. Creek / River photo

Photo 17- 12:25 P.M. - Screen shot of location from Trail App

Text Message Attempt:

The following text message was attempted but not successful due to not having cellular service on the area.

11:56 A.M. - “{name redacted} can you help us. On savage lundy trail heading back to Hites cove trail. No water or ver (over) heating with baby.”

Phone call Attempts:

The following phone calls were attempted to multiple phone numbers, not including 911. There is no service in the area, therefore the calls were never connected.

Call 1- 12:09:20 P.M.

Call 2- 12:35:48 P.M.

Call 3- 12:36:06 P.M.

Call 4- 12:36:19 P.M.

Call 5- 12:36:24 P.M.

“The cell phone data results were the last thing both the family and detectives were waiting on. 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," said, Sheriff Jeremy Briese.

Source: Mariposa County Sheriff

Related: Mariposa County Sheriff Provides Final Update on Deceased Family Hiking Near Devils Gulch in August