SAN FRANCISCO (Map, News) - Police and prosecutors may have wrongly jailed a Daly City man for more than three weeks in the case of a double slaying outside a Sunset district pizzeria.

On the first day of a preliminary hearing for Matthew Owyang, 19, Tiffany Chan admitted to lying police and named a previously unknown witness as a fifth person with her in the getaway car.

Chan, 19, who told several stories to police in interviews after the killing of Jason de la Cruz, 31, and Derek Butch, 23, early March 29 outside a pizzeria at Irving Street and 19th Avenue, said Monday during testimony that she lied to police because investigators “caught me off guard … and I was scared.”

She named another 19-year-old, Eric Siu, as a man who was fighting with de la Cruz earlier and who jumped into Owyang’s blue two-door Honda. Owyang was standing next to the open door during the shooting, according to Chan.

Owyang’s attorney, Bill Fazio, said he knew all along his client was innocent and that’s why he demanded a speedy trial. Fazio told police a week ago about the other suspect, and he told Assistant District Attorney George Butterworth the morning of the preliminary trial.

“Everybody on the street knew that Eric Siu was the shooter, except for the cops and the DA,” he said outside the courtroom.

Police arrested Owyang on a Ramey warrant on April 1, and the District Attorney’s Office filed charges soon after.

bbegin@examiner.com