A suspect is a person who is believed to be linked with a crime. Commonly, law enforcement officials think that the suspect is the perpetrator, the person who actually committed a crime.

Depending on the nature of a case, several suspects may emerge and be eliminated with the assistance of detective work, or police may only have a single suspect to work with. Sometimes no suspect emerges. If a witness positively identifies someone as the person who committed a crime, that person is more properly known as the perpetrator.

The difference between suspect, accused, and perpetrator can get a bit complicated, and these terms are sometimes misused, especially in the press. When law enforcement personnel believe that someone has committed a crime without any solid proof, that person is considered a suspect. Suspects may have behaved unusually, left trace evidence at a crime scene, and so forth, but they have not been positively identified as the actors who committed the crime.

Suspects may be temporarily taken into custody for questioning, and they may also be asked to submit samples of hair, fibers, and so forth to see if they can be matched with evidence found at the crime scene. If a suspect is formally brought to trial, he or she becomes the accused. The accused is entitled to an assortment of rights which are not available to a suspect, in recognition of the fact that the accused needs to be able to mount an effective defense in court. If the outcome of a trial is a guilty verdict, the accused becomes the convicted, and goes on record as the perpetrator.

Police sometimes use the term "person of interest" to describe a suspect. This term is used in part because of the negative associations with the word "suspect." Many members of the general public confuse suspects with perpetrators, and when it is announced that someone is a suspect in a case, the public may assume that this means he or she actually committed the crime. A person of interest, on the other hand, is simply someone the police would like to have a conversation with.

The use of the term "suspect" to describe someone who may be involved with a crime dates back to the late 16th century. Since then, the legal system has changed radically, and there are many steps between being listed as a suspect and being convicted of a crime. Suspects are also entitled to certain legal rights in many nations such as the right not to implicate themselves in a crime, and typically they can only be held in custody for a brief period of time before they must either be formally charged or released.