LOS ANGELES (AP) — A rookie Southern California police officer slain in an off-duty shooting was the victim of an attempted robbery, a prosecutor said Wednesday. Los Angeles County District Attorney George Gascón revealed the alleged motive as his office filed charges against a man and a 17-year-old boy in the killing of Monterey Park police Officer Gardiel Solorio, 26. Carlos Daniel Delcid, 20, was charged with one count each of murder, attempted robbery and possession of a firearm by a felon with the special circumstance allegation that the murder was committed during a robbery. Delcid was expected to be arraigned Thursday. It was not immediately known if he had an attorney to comment on the allegations.