The body was found around 7:30 a.m. in a small parking lot near Fourth Street and Tamalpais Avenue by a business owner arriving for work, Rohrbacher said.
Police are investigating the death as "suspicious" and are withholding additional details pending further investigation. Officers said they did not have a lot to go on in the probe.
The parking lot is at the eastern end of the downtown area and there are several bars, a pizza restaurant, a liquor store and a bus terminal nearby.
Tamalpais Avenue is closed between Third and Fourth streets this morning, Rohrbacher said.