A police lineup is a process used by detectives and police officers to try and identify suspects in a criminal action. The police generally invite the victim of the crime in question or a witness to the crime to attend a viewing or lineup of who the police suspect is the culprit along with several other people that are of similar height, weight, build and complexion. The extra people used are often actors, volunteers or prisoners. The group of potential suspects stand side by side. Most of the time the viewing takes place in a room where the people in the lineup cannot see who is attempting to identify the suspect. This is done to ensure the witness or victim can remain anonymous. The lineup must be conducted fairly, and the police are not allowed to try to sway the victim or witness to choose a particular person.