Task: Explanation
Input (English): The Zodiac Killer or Zodiac was a serial killer who operated in northern California in the late 1960s and early 1970s. The killer's identity remains unknown. The Zodiac murdered victims in Benicia, Vallejo, Lake Berryessa, and San Francisco between December 1968 and October 1969. Four men and three women between the ages of 16 and 29 were targeted. The killer originated the name "Zodiac" in a series of taunting letters sent to the local Bay Area press. These letters included four cryptograms (or ciphers). Of the four cryptograms sent, only one has been definitively solved. Question: The pornahraphic film based on the unidentified killer of four men and three women, in the Bay Area in the 1960's and 1970's was released in what year? Answer: 1971
Output (English):  The killers identity remains unknown.