Next, investigators select five plainclothes detectives to participate in the lineup with the subject. Even though the dogs identify suspects by scent alone, lineup participants ideally should be the same race and sex as the suspect. All participants, including the suspect, must wash their hands with a neutral soap to eliminate any foreign odor. Each member of the lineup stands behind a glass jar, which officers have placed on the floor of the lineup room. On command, each person opens the glass jar, retrieves the pipe it contains, holds the pipe for 5 minutes, then places the pipe back into the container.
Police officers supervise the entire process.
Each position on the floor corresponds to a number, from 1 to 6. Police officials document this information in writing. Before the dog and its handler enter the lineup room, the person who places the pipes on the floor leaves the room, removing the glass containers. This ensures that no one influences the dog prior to the lineup. The dog handler and the detection dog enter the room, and the handler uses forceps to hold the evidence over the dog's nose.