alibi - The suspect's claim that he or she was not near the scene of the crime when it took place.
clue - Something that leads or appears to lead the detective closer to solving the crime.
deduction - Logically using the facts to arrive at a conclusion.
evidence - Proof of who the villain is.
interrogation - Questioning by the detective of all the suspects in the case.
red herring - A false clue intended to throw the detective off the track.
sleuth - Someone who investigates and solves a crime.
suspects - The people who are connected to the crime in some way and seem to have a reason for committing it.
witness - A person who discovers a crime or has information about the crime.