A police tester to detect the presence of a target substance includes a housing adapted to be mounted in a police cruiser; a chemical reservoir insertable into the housing; a test swipe in a disc or an automated cartridge, the test swipe adapted to receive a chemical from the chemical reservoir, the test swipe including one or more chemically treated pads; a camera to capture an image from the test swipe; a processor coupled to the camera to process the image to detect the target substance; and a transmitter coupled to the processor to transmit a test result to a remote computer at a police headquarter.