A Sun Valley man was killed and a police officer injured in an accident that occurred while officers were pursuing a motorcyclist at speeds up to 70 m.p.h. Los Angeles police said Robert Wade Still, 18, of North Hollywood and his brother, who was arrested after a separate chase, were drag racing near Glenoaks Boulevard and Peoria Street in Sun Valley. Officer Lee Glozer, 39, was pursuing Still when his patrol car and a pickup truck driven by David Malekian, 54, collided at the corner of Tujunga Avenue and Strathern Street, police said. Malekian was pronounced dead at the scene and a motorcycle officer who continued the chase arrested Still at his home and booked him on suspicion of murder. Glozer was released after treatment for cuts and bruises.