The Zodiac Killer
This is one of the most unforgettable serial killers probably because the case file is still open until now. There was no suspect caught despite the fact that he has committed murder of around 37 people with 7 of them confirming that he was the actual murderer. He operated in California from 1960 to 1970. He kept leaving ciphers that were to be decoded by the police. Unfortunately, no one was captured and brought to justice to this age.
