Calling card (crime)
In criminology, a calling card is a particular object sometimes left behind by a criminal at a scene of a crime, often as a way of taunting police or claiming responsibility. The name is derived from the cards that people used to leave when they went to visit someone's house and the resident was absent. A calling card can also be used as an individual's way of telling someone they are alive after they have run away or disappeared without revealing themselves or having direct contact with that person. It is often left at a  bed side table while the person is asleep, at the living room floor and sometimes even at a grave yard if they know the times someone goes to visit their loved ones. However, some criminals choose not to leave a calling card, as it may be used by authorities or detectives to trace the criminal, and eventually arrest them.