alibi

an excuse than an accused person uses to show that he/she was somewhere else than at the scene of the crime

breakthrough

an advance or discovery that helps solve a crime

clue

a fact or object that helps to solve mysteries

detective

a person who investigates crimes and gathers information

evidence

 something, such as a witness statement or 
object that is used as proof in a crime

hunch

a guess or feeling not based on known facts

motive

an inner drive that causes a person to do something or act in a certain way

mystery

something that is secret and unknown

plot

the arrangement of incidents in a story

red herring

something that is used to divert attention from the basic issue

setting

the time, place, environment and surrounding circumstances of a story

sleuth

another name for a detective

suspect

a person who is suspected of a crime

victim

someone who is harmed or suffers some loss

witness

someone who saw or can give a firsthand account of something