Victor Flores said he was in the bathroom of his Petaluma home last week getting ready for work shortly after 4 a.m. when an explosion shattered the predawn silence, followed by a scream. He immediately thought his wife was being attacked as she returned home after working the night shift, Flores said. In fact, dozens of federal agents had converged on their McNeil Avenue house to arrest their oldest son, also named Victor Flores, and search the rental house as part of an investigation into a 2010 triple homicide in South San Francisco. The quiet neighborhood was awakened by loud...