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MARIPOSA, Calif. – The investigation continues into the puzzling deaths of a Northern California family and their dog after they were found earlier this year in a remote hiking area in the town of Mariposa.

The Mariposa County Sheriff’s Office said Thursday the causes of death for John Gerrish, his wife, Ellen Chung, their 1-year-old daughter and their dog remains “undetermined.” Their family’s vehicle and later their bodies were found Aug. 17 in the Hite’s Cove area of the Sierra National Forest, along the Southfork of the Merced River, FOX 5’s sister station KSEE reported.

Officials closed access to trails in the area following the incident due to “unknown hazards found in and near the Savage Lundy Trail.”

Although it is not clear how they died, investigators said they’ve ruled out death by gun or other weapon, lightning, carbon monoxide, carbon dioxide, cyanide, illegal drugs, alcohol or suicide.

“We respect and understand the need for information and details regarding this case,” Sheriff Jeremy Briese said in a statement Thursday. “Our current priorities remain supporting and informing the Gerrish/Chung family during this tragic time. As we navigate through this investigation with the family, we will later share our findings with the public.”

A friend of Gerrish and Chung told KSEE in August that the family owned rental properties in Mariposa, noting that Gerrish was from the United Kingdom and Chung was from San Diego.

According to the department, its detectives are working with a number of specialists, including a toxicologist, an environmental specialist and the FBI, to crack the case open. They’re in the process of conducting interviews and investigating “all potential possible explanations,” the release shows, and “many” toxicology reports also have been administered.

No timeline has been set to release those pending results, the department said.

The Associated Press contributed to this report.