The private investigator who allegedly planted a tracking device on Richard Simmons' car has been charged with a crime ... TMZ has learned.
Scott Brian Matthews was charged with 2 counts of the crime of unlawfully using a tracking device.
Prosecutors say Matthews planted the device on the car Richard bought for his housekeeper, Teresa Reveles. They say he planted it so he could shadow Simmons and see if he was going to doctors or hospitals.
Simmons sued Matthews last month, claiming he was hired by the National Enquirer to keep tabs on him. The Enquirer had published a story claiming Simmons was undergoing a sex change. Simmons sued the Enquirer but the case was dismissed.