MARIPOSA — Authorities are awaiting key toxicology test results in the mysterious deaths of a family and their dog in a remote Sierra hiking area.

Progress in solving the case the six-week-old case is limited to ruling out death by a gun or any other weapon, a lightning strike, carbon monoxide, carbon dioxide, cyanide exposure, illegal drugs, alcohol, or suicide, the Mariposa County Sheriff’s Office said.

The bodies of John Gerrish, his wife, Ellen Chung, their 1-year-old daughter, Miju, and their dog were found on Aug. 17 on a hiking trail close to the Merced River in the Sierra National Forest. A family friend reported them missing.

“We respect and understand the need for information and details regarding this case. 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. ” said Mariposa County Sheriff Jeremy Briese in a news release.

Toxic Algae Not Ruled Out

The Mariposa County Sheriff’s Office said Thursday that officials are working with toxicologists, environmental specialists, the FBI, and other experts, but “the cause of death remains undetermined.”

“All other potential causes of death remain,” the sheriff’s office said, without elaborating.

While many toxicology reports are complete,  authorities await a “few key results. However, there is no timeline for those, the department said.

One early theory that has not been ruled out is whether high levels of toxic algae detected played a role.

Investigators have received results from water samples in the area but are still waiting for other test results to help determine if the levels were high enough to cause the deaths, said Kristie Mitchell, a spokeswoman for the sheriff’s office.

Authorities have sent the couple’s phones and computers to the FBI, she said.

“We haven’t ruled out much, other than what we’ve listed,” Mitchell said. “Everything else is still out there as an option.”

(GV Wire contributed to this report.)