In the parlance of criminal justice, a suspect is a term used to refer to a person, known or unknown, suspected of committing a crime.

Under the judicial system of US, once the identity of a suspect is known, and a decision is approved to arrest him or bind him over for trial, either by a prosecutor issuing an information, a grand jury issuing a true bill or indictment, or a judge issuing an arrest warrant, the suspect can then be properly called a defendant.