Who was the Zodiac killer?

The Zodiac killer was a serial killer in California, supposedly responsible for five murders and two failed attempts that took place from 1968 to 1969. He created a sensation and a scare by publishing letters in newspapers with Zodiac as his pen name. In his letters, he used to claim responsibility for murders that had taken place and would disclose his plans for future murders. His letters would also contain cryptograms of which only a few were cracked. Neither the decoded cryptograms nor the other evidence related to him helped the police establish his identity. The Zodiac killer has become the subject of several novels and films.