High Quality Content by WIKIPEDIA articles! The Quadro Tracker, also known as the Positive Molecular Locator, was a "detection device" sold by Quadro Corp. of Harleyville, South Carolina between 1993 and 1996. Around 1,000 were sold to police departments and school districts around the United States on the basis that it could detect hidden drugs, explosives, weapons and lost golf balls. In 1996, the FBI declared it to be a fake and obtained a permanent injunction barring the device from being manufactured or sold. Three principals of Quadro Corp. were charged with mail fraud and conspiracy to commit mail fraud, but were acquitted in a trial held in January 1997.