Tiburon police are investigating a rare homicide in that waterfront town.
The 75-year-old woman was found by a friend lying in a pool of blood on an enclosed patio just outside her front door on Hilary Drive.
She has been identified as Joan Rosenthal
The police chief said she died of a gunshot wound to the head and was declared dead at the scene. He said there were no signs of a break in and that nothing had been taken from the home.
Police said Rosenthal's husband had recently died and that suicide had been ruled out as a cause of death.
This is the first homicide in Tiburon in a decade and just the fourth since 1970.
Tiburon police Sgt. Shane Ford said such an occurrence is rare for the city. "We don't have violent crime in Tiburon," he said.
Hilary Drive is a stretch of road that is only a couple blocks long and is just east of Highway 131. It is near Richardson Bay Lineal Park.
Anyone with information about the shooting is asked to call the Marin County Sheriff's Department at 415-499-7265 or Crime Stoppers at 800-222-8477.