Jack The Ripper
There was an unidentified serial killer in London who killed 11 women in the late 1800s. A lot of movies and shows were created as inspired by Jack the Ripper. Prostitutes were the target of the said killer. The bodies are slashed beyond recognition. Despite the bloody crime scenes, Jack the Ripper remained anonymous.
This is found in the statue with coded encryptions outside the CIA headquarters in Langley, Virginia. The statue was created by Jim Sanborn. It was designed to show that nothing can be left unresolved and everything can be decoded using clues and patterns. Only the first three encryptions were cracked. The fourth remained unsolved. Not even all CIA brilliant minds were able to uncover the said encryption.