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UPDATE: San Francisco Family Found Dead in Sierra Foothills Not Exposed to Chemicals from Mine

SAN FRANCISCO (CBS SF/AP) -- Authorities released new details Thursday regarding the mysterious deaths of a San Francisco family found on a California hiking trail last week.

John Gerrish, his wife Ellen Chung, their 1-year-old daughter Miju and the family dog were all found dead on a hiking trail near Hite's Cove in the Sierra National Forest on Aug. 17th.

UPDATE: Feds Close Portion of Merced River Near Where Family Died Mysteriously

On Thursday, investigators announced they have ruled out exposure to chemicals from a mine located near the trail.

Authorities also said they believe the family hiked more than eight miles in triple-digit heat with little to no shade from trees.

Investigators are still waiting for toxicology reports and cell phone data.

The family lived in San Francisco, but moved to Mariposa County during the pandemic.

The area in the Sierra National Forest where the bodies were found on Aug. 17th had been treated as a hazmat site after concerns were raised about the deaths being linked to potentially toxic gases from old mines nearby.

The area around Hite's Cove was the site of a hard rock gold mining operation in the mid-19th century.

But the hazmat declaration was lifted the following day, and Mariposa County Sheriff Jeremy Briese said he didn't believe the mines were a factor, the Fresno Bee reported a week ago.

"This is a very unusual, unique situation," said Kristie Mitchell, a spokesperson for the sheriff's office. "There were no signs of trauma, no obvious cause of death. There was no suicide note."

The couple were known to be avid hikers. Their friend, Mariposa real estate agent Sidney Radanovich, said Gerrish was a San Francisco-based software designer who, with his wife, "fell in love with the Mariposa area" and bought several homes there, a residence for themselves and rental investments.

According to the Fresno CBS affiliate, Gerrish was from the United Kingdom and met Ellen Chung in San Francisco before they relocated to Mariposa during the pandemic in 2020. reported that Gerrish had been working for Snapchat.

© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.

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