Motorists discovered human remains down an embankment near Point Reyes Station on Friday evening, according to a spokesman with the Marin County Sheriff's Office.
The discovery was made at about 6 p.m. near Platform Bridge Road in an unincorporated part of the county, Lt. Doug Pittman said.
The drivers noticed something suspicious and stopped to investigate. The remains they found had been wrapped in some sort of plastic material, but had been left out there for quite some time, Point Reyes National Seashore spokesman John Dell'Osso said.
Dell'Osso said that it remains unclear whether the remains were moved from another location. Also, the gender of the body is still unknown.
The road was closed between Sir Francis Drake Road and Point Reyes-Petaluma Road, during the lengthy investigation. It was reopened in the evening.
Sheriff's officials are working with park service officials, as well as the FBI, who are on scene since the body was found on federal park land, according to Pittman.
FBI investigators are expected to remove the remains sometime later this afternoon and will work with the Marin County Coroner to determine the victim's identity and cause of death, according to Dell'Osso.
Marin County sheriff's officials posted a message on Twitter that showed search and rescue teams combing the area for evidence related to the criminal investigation. There is no threat to the community, they stressed.