The real-life Hollywood mystery began Tuesday afternoon when two people noticed their dogs dragging a plastic grocery bag from a bush near a dirt trail, police said. The women were shocked when they realized a severed head was inside.

In an interview with HLN, Kornberg, the dog walker, said she was walking eight dogs when one of them, a golden retriever named Ollie, ran away from her. Kornberg was joined by her mother, who was walking her own dog.

"We were wandering the trail and the dogs are sniffing around, and he (Ollie) pulled away from me and made a beeline for some brush. He was barking," Kornberg said.

"A few minutes later, he had something in his mouth, which he immediately dropped," Kornberg said.

The object rolled down the ravine, Kornberg said.

Kornberg and her mother discovered it was a human head belonging to what she described as a white man.

"We were pretty much gasping, saying, 'Oh, my God!' I was shaking. It felt like a script," Kornberg said. "It still doesn't feel real."

The secluded trails, adjacent to Griffith Park, are a favorite place for residents, including many celebrities, to walk their dogs or hike.

The coroner's office is examining whether the man was dead when the dismemberment occurred, and what kind of instrument may have been used to remove the head and limbs, Smith said.

Police don't have a theory on what happened.

"Right now, we're keeping an open mind ... on why this poor person was dismembered and deposited up there," Smith said.

Detectives estimated the man had been dead since Sunday.

Police are also checking recent missing-person reports for leads, Winter said.