A high-ranking police official at a Massachusetts hospital and a former high-school librarian were charged on Monday in a plot to kidnap, torture and kill women and children, federal prosecutors said. Richard Meltz, the 65-year-old chief of police for the Bedford Veteran Affairs Medical Center in Massachusetts, and Robert Christopher Asch, a former librarian at Stuyvesant High School in Manhattan, were held without bail after appearing in U.S. District Court in Manhattan and charged with conspiracy to kidnap, torture, rape and kill women and children—including the wife and children of a cooperating witness. Peter Brill, an attorney for Mr. Meltz,...