A young man pleaded not guilty Monday to murder in connection with a 13-year-old boy’s shooting death at a Pico Rivera gas station where the victim’s mother was working. Chavez was arrested Aug. 28 by Los Angeles County sheriff’s deputies in connection with the Aug. 23 killing of Saith Toledo Mendez at a gas station in the 8800 block of Whittier Boulevard. “Unprovoked, suspect Chavez drew a firearm, took several steps toward Saith and shot him at close range,” the sheriff said. The boy’s mother watched as the gunman shot her child “in the back without prior interaction,” Luna said. In a statement released a day after the case was filed, District Attorney Nathan Hochman said, “What happened at this gas station is every parent’s worst nightmare.