Petaluma teen guilty of fatally shooting friend whose body was found in Santa Rosa alley

A Petaluma teen was found guilty Monday of fatally shooting his friend last year while they were both inside a car that was driving away from a fight they’d been in downtown Santa Rosa.

Sonoma County Juvenile Court Judge Ken Gnoss issued the ruling on the final day of the trial of Anthony Partida-Velasco, who was charged with second-degree murder and assault with a firearm in the March 19, 2022 shooting of Dominic Zumsteg, 24.

Partida-Velasco, who was 17 at the time of the shooting, is scheduled for a disposition hearing, or sentencing, on Aug. 22.

Following Monday’s adjudication, defense attorney Walter Rubenstein told The Press Democrat his client can be rehabilitated.

Partida-Velasco, he said, had already completed high school through an unspecified jail program and is now taking junior college courses.

“Other than this event, he seems like a bright young man,” Rubenstein said.

In making his decision, Gnoss said there was a “plethora of circumstantial evidence” the defendant fired a gun the night his friend was killed.

According to Santa Rosa police, the series of events leading to the shooting began late March 18, 2022 when Partida-Velasco, Zumsteg and two others went to The Dirty bar, 616 Mendocino Ave., in downtown Santa Rosa.

They couldn’t enter because Patrida-Velasco and one of the others were minors.

Outside, they got into a fight with another group for unspecified reasons before leaving in a Chevrolet Malibu driven by Petaluma resident Antonio Boyd, then 24.

They headed south on Mendocino Avenue with Zumsteg in the front passenger seat and Partida-Velasco behind him. Partida-Velasco fired three rounds from a handgun as the vehicle drove from the scene and the third round struck Zumsteg in the back.

It wasn’t clear if shots were being fired randomly or aimed at the group involved in the fight.

Partida-Velasco hid the gun under a bush on College Avenue, where a passerby found it weeks later.

Surveillance footage showed the group pulling up to a business in the 800 block of Fourth Street, removing a body from the car and placing it in a nearby alley.

They fled after Partida-Velasco got in the front seat.

“He didn’t make any attempt to get help,” Sonoma County Deputy District Attorney Marianna Green said during Monday’s hearing.

Authorities were investigating the gunfire when they discovered Zumsteg and brought him to Providence Santa Rosa Memorial Hospital, where, he was pronounced dead.

The three defendants were pulled over on Brookwood Avenue and later arrested.

Last year, Boyd pleaded guilty to being an accessory to murder and sentenced to one year in jail and two years of probation.

The third suspect was described as a 17-year-old boy and also charged with being an accessory to murder. Officials couldn’t comment on his status because his case was a juvenile matter.

During Monday’s hearing, Rubenstein contended his client acted with negligence and Boyd was mostly responsible for Zumsteg’s death. He maintained Boyd was responsible for the fight at the bar and drove the car afterward.

“Mr. Boyd’s actions that night were callous,” Rubenstein told Gnoss. “Boyd continued to create these reckless circumstances.”

Boyd testified during Patrida-Velasco’s trial.

Sonoma County jail records did not list him as an inmate and he could not be reached for comment Monday.

You can reach Staff Writer Colin Atagi at colin.atagi@pressdemocrat.com. On Twitter @colin_atagi