What term is used for a person believed to have committed a crime?

The term used to refer to a person believed to have committed a crime is "suspect." In a criminal justice context, a suspect is an individual that law enforcement authorities have reasonable grounds to believe may have been involved in the commission of a criminal act. This designation comes into play during investigations when law enforcement gathers evidence suggesting someone's potential involvement in illegal activities.

The other terms listed are related to different roles in the justice process. A witness is someone who sees an event or has information relevant to a crime. A victim is the person who suffers harm as a result of the crime. A complainant is an individual who makes a formal complaint, typically to law enforcement, about the commission of a crime, but this doesn't equate to being someone believed to have committed the crime themselves. Therefore, "suspect" is the accurate term for an individual thought to have engaged in criminal behavior.