Skull found in Sonoma County identified as 1980s homicide cold case victim

(KRON) — The Sonoma County Sheriff’s Office identified the skull of “‘Motorcycle Mountain’ John Doe” as Thomas Jeffrey Rupen, the victim of a cold case dating back to the 1980s, officials announced Tuesday.

On Feb. 15, 2001, a civilian turned a human skull into the sheriff’s department office in Santa Rosa. The civilian said they found it on “motorcycle mountain” near Duncan Road in Monte Rio, officials said. Officials could not find any other remains.

But anthropologists were able to determine the skull belonged to a white man between ages 25 and 40. They also determined he was likely the victim of a homicide.

In 2022, the police submitted the skull to the DNA Doe Project, which connected the skull to Rupen’s brother, confirming the identity as Jeffrey Thomas Rupen.

Police said Rupen was born in North Carolina in 1958. He studied political science at Columbia University in New York City, where he was living and working in 1980 when he became estranged from his family.

Police said at some point he visited California and was rumored to have become a house painter.

The Sheriff’s Office is asking anyone with information on Rupen’s life or death contact them at 707-565-2727 or

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