Richard Simmons Sues P.I. For Planting Tracking Device Over Transgender Story

Richard Simmons has sued a private investigator who he claims put a tracking device on his car to help tabloids prove what appears to be a false story that the fitness guru was undergoing a sex change.

Simmons and his caretaker, Teresa Reveles, filed the suit against P.I. Scott Brian Matthews, claiming he put a tracking device on Reveles car so he could shadow Simmons and see if he was visiting hospitals.

Simmons gets around L.A. in Reveles' car ... he relies on her for transportation.

The suit claims the device was attached to Reveles' car for more than a year.

Simmons claims Matthews has used at least 17 tracking devices to shadow more than a dozen people.

Richard says when he and Reveles discovered the tracking device he suffered mental anguish, anxiety, feeling of powerlessness, frustration and humiliation.

Simmons sued the National Enquirer for defamation after it published a story saying he was in the middle of a sex change. A trial judge dismissed the case, ruling that calling someone transgender does not expose the person to hatred or ridicule. Simmons is appealing the dismissal.