Richard Becker, a San Francisco activist, said he came up for his fourth protest.
"I think it's very important that this issue not be allowed to die," he said. "It's not going to fade away."
In shouted slogans and on T-shirts and signs, the protesters called for criminal prosecution of Gelhaus and for Sonoma County District Attorney Jill Ravitch to recuse herself from the case.
The protest slimmed to about 100 people as marchers arrived at the Police Department's front doors, where 16 officers in riot gear and holding batons stood still behind traffic barricades.
"We're not your enemies," someone shouted as the marchers pressed up next to the barricades.
The rally disbanded at 3:45 p.m.
You can reach Staff Writer Guy Kovner at 521-5457 or firstname.lastname@example.org.