Hopfe's body was found by a hiker near Sir Francis Drake Boulevard in the area of Platform Bridge Road around 9:45 a.m. Thursday.
The National Park Service has asked the Marin County Sheriff's Office to investigate the death, sheriff's Lt. Jamie Scardina said.
The sheriff's office is interviewing witnesses to determine a motive, and there is no suspect or suspect description at this time, Scardina said.
Anyone with information is asked to call the sheriff's office at (415) 473-7265.
