A suspect in a rape case was captured Monday because an alert pedestrian saw a man dragging a weeping 15-year-old girl down the street by her neck, police said. Jorge Alberto Ek-Luna, 26, was arrested near San Rafael High School as he tried to kidnap the girl using a broken bottle to threaten her, police spokeswoman Margo Rohrbacher said. Ek-Luna, a recent immigrant from Mexico who was staying in San Rafael, was booked on charges including rape, kidnapping and assault with a deadly weapon.