An unsolved mystery lasting over half a century surely seems to be the plot of a movie. While the mystery did make it to the silver screen and still remains unsolved, a big piece of the puzzle finally has been cracked after 51 long years. The mystery is about the Zodiac Killer who terrorized Northern California in the 1960s. While the killer's identity remains unknown to date, some amateur code breakers have claimed to solve one of his coded letters to the San Francisco Chronicle, called "340 cipher".

The killer claimed to have murdered 37 people but only five have been officially linked so far. However, one of the most interesting aspects of the case was the killer's letters to police and local newspapers. The four letters that he sent were unusual. It contained a mixture of zodiac symbols and English alphabets. While one of the correspondences had been deciphered, "340 cipher" had been a challenge for code breakers for over 50 years, until now.

Zodiac killer
Sketch of the Zodiac killer (L) and the 340 cipher which remained unsolved for over 50 years Wikimedia Commons

'Breakthrough'

Software developer David Oranchak from Virginia, Australian mathematician Sam Blake and Belgian programmer Jarl Van Eycke have claimed to solve the letter. The trio informed the FBI about their breakthrough a week ago and the agency confirmed it on December 12.

The 340-character ciphered message was sent to the Chronicle in November 1969 and contained all capital letters without any punctuation. According to the code breakers, the word 'paradise' was misspelled.

The TV show that the killer was referring to was "The Jim Dunbar Show". The television talk show received a telephone call from a person who claimed to be the Zodiac killer. The letter was sent two weeks after the show was telecast, CNN reported. However, the call appeared to be a prank from a mental patient.

FBI Confirms

The FBI confirmed the works of the code breakers and said that the agency's Cryptanalysis and Racketeering Records Unit (CRRU) had reviewed their findings. However, the agency declined to comment any further as the investigation remained open till the date.

"When I first started, I used to get excited when I would see some words come through. They were like false positives, phantoms. I had grown used to that. It was a long shot and we didn't even really know if there was a message," said Oranchak.

Many other codebreakers attempted to decipher the letters in many documentaries and privately but none of them had merit. "Over the past 51 years, CRRU has reviewed numerous proposed solutions from the public — none of which had merit. The cipher was recently solved by a team of three private citizens," the FBI confirmed.

Oranchak took interest in the cipher in 2006. Since then, he had tried to solve the mystery but had to be disappointed. With the other two's help, a proper conclusion was reached on the letter. "It was incredible. It was a big shock, I never really thought we'd find anything because I had grown so used to failure," Oranchak said.

This is only the second time that a letter from the Zodiac killer has been solved. In 1969, a schoolteacher and his wife from Salinas, California solved one of the ciphers, a long letter sent in parts to the San Francisco Chronicle, San Francisco Examiner and the Vallejo Times-Herald in 1969. However, even though the letter has been deciphered, it does not contain any identifiable information that could point towards the killer. So far, it remains a cold case and is open to speculation about the real identity of the murderer.