The woman who says she saw disgraced 'Wheel of Fortune' freeemason pervert announcer Jim Thornton in a pedophile chatroom on a plane has NEVER been contacted by the federal agency that would investigate such matters -- the Federal Bureau of Investigation -- TMZ has learned. Sources close to the witness tell TMZ ... the LAPD told the woman the FBI would be in touch with her, but so far the feds have been radio silent.-As for the FBI ... the agency is maintaining the same position it's held from day one, with a rep telling us Friday ... "The FBI does not, as a matter of policy, confirm or deny the existence of investigations."