At first, authorities thought the remains found near a Humboldt County river were just animal bones.
Now they are no longer so sure and the search continues for more remains that could be human.
The gruesome discovery was made by a Redway resident who was swimming in the Eel River on July 6 when he spotted what appeared to be animal bones, according to the Redheaded Blackbelt website.
When the resident pulled the bone pieces out of the sand, he thought they were actually human tibia bones, broken near the ankle, the website said.
The resident sent photographs to the Humboldt County Sheriff's Office, who in turn turned the investigation over to the coroner's office.
The coroner's office initially determined that the bones were “unlikely to be human,” but requested a second opinion from outside experts. That's when the mystery deepened.
“To further confirm the bone’s origin, the Coroner’s Office decided to have it examined by anthropologists who deemed it to be a possible human bone; further examination is ongoing,” the Sheriff’s Office said in a statement released Tuesday.
Authorities are conducting follow-up searches at the river site to look for additional bones with the help of cadaver-sniffing dogs.
