NEW YORK — Federal prosecutors planned to use a graphically detailed trail of emails, computer files and instant messages to show that a New York City police officer had dangerous schemes to abduct women, cook them and devour them.Opening statements were expected early Monday afternoon in the case against 28-year-old Gilberto Valle."I'm planning on getting me some girl meat," Valle allegedly wrote in one chat room. "It's this November, for Thanksgiving. ... She's not a volunteer. She has to be abducted."