A Force Signature was the identity of a being in the Force. It left behind a mystical residue, that withered with time, that identified them. Like fingerprints, signatures were unique to each being and could be used to identify a criminal if the investigator was a trained Jedi or one with specific Force identification equipment. The most visible example of a Force Signature is the Force Ghost that appears when an exceptionally centered Jedi becomes one with the Force. Jedi could determine the identity of a being by their signature through various methods: strength of the Force user, use of the Force and the familiarity of the signature based on previous encounters. There were two ways that a being could be identified by those methods: Post-use and Active-Use. Post-use was the impression le