An Alameda County sheriff's deputy was speeding when he struck and killed a pedestrian and injured another near Hayward last year but won't be criminally charged, authorities said.

Deputy Jonathan Hamm was traveling above the speed limit in a marked Dodge Charger near Mission Boulevard and Cherry Way in the unincorporated Cherryland neighborhood about 4:30 a.m. April 19, 2013, when he hit 38-year-old Valdemar Flores-Rosas of Hayward and Delia Delgadillo, according to a California Highway Patrol investigation.