Oliver North may have lied to FBI agents to get them to investigate his political adversaries two years ago, according to documents and sources close to the inquiry. North told the FBI he had been followed, his car was vandalized, his tires were slashed and his dog was poisoned, but after months of looking into the reports, FBI agents came to believe he may have concocted the harassment story to spur a criminal investigation into several people he believed threatened to expose his secret aid to the Nicaraguan Contra rebels, evidence shows. Moreover, the alleged effort to manipulate the bureau backfired when agents eventually turned their sights on the Marine lieutenant colonel, sources say.