A French engineer claims he has learned the identity of the Zodiac Killer after solving his two remaining ciphers. Fayçal Ziraouitold the New York Times, he started working the case during the coronavirus pandemic after reading an article in a French magazine about how a team of amateur codebreakers cracked a previously unsolvable cipher from the killer.

The codebreakers put the encryption key online, and Ziraoui decided to use it to solve the remaining two ciphers, Z32 and Z13, which are 32-characters and 13-characters long.

The letter that contained the 32-character cipher warned that a bomb would go off at a school and told investigators they had to solve the puzzle to find out where the bomb was hidden. While investigators failed to decipher the cipher, no bomb ever went off at a school. When Ziraoui applied the encryption key to the cipher and got a random group of letters.

He wasn't going to stop there and spent weeks trying different code-cracking techniques.

"I was obsessed with it, 24 hours a day. That's all I could think about," Ziraoui said.

After two weeks, he finally solved the cipher, which reads "LABOR DAY FIND 45.069 NORT 58.719 WEST."

The coordinates matched up with a school in South Lake Tahoe, California. That same school was referenced in a postcard sent by the Zodiac Killer in 1971.

Ziraoui then set to cracking the 13-character cipher, which was supposed to reveal the killer's identity. It took him just an hour to solve the cipher, which spelled out "KAYR."

Ziraoui believes that referred to Lawrence Kaye, a career criminal who lived in South Lake Tahoe and was suspected of being the killer. He died in 2010. Ziraoui explained that the Zodiac Killer made a typo, similar to the ones he made in other ciphers.

When Ziraoui posted his findings online, he was shut down and met with criticism. His post on a subreddit about the killer was deleted within 30 minutes. The moderator said there is a policy against posting solutions to the remaining ciphers because they are unsolvable. Many code crackers believe they are too short to determine the encryption key and that there is no way to definitively prove that an answer is correct.

David Oranchak, who helped crack the 340-character cipher, explained that there are "hundreds of proposals for Z13 and Z32 solutions" but that "it is practically impossible to determine if any of them are correct" in a written exchange.

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