In November 1969, the Zodiac killer sent what would be known as the 340-cipher, a hodgepodge of 340 symbols that confounded police and the public. Nearly 40 years later, the cipher remains unsolved.
A UNT undergraduate computer science class took a shot at cracking the code last year by developing software capable of breaking substitution ciphers. Experts think the 340-cipher is a substitution code similar to an earlier Zodiac cipher sent to California newspapers and solved by a husband and wife.
The class wasn't able to decipher the code, but the work did attract the attention of National Geographic. UNT faculty member Ryan Garlick appeared on Code Breakers, a National Geographic documentary on codes, ciphers and cryptographs that aired on March 1 on the National Geographic network. Watch highlights from the program.
"We don't know if the cipher will ever be solved," says Garlick, who is an assistant visiting professor in computer science and engineering. "We brought a few new techniques to the table along with considerable computational resources, but it's impossible to say whether we got close."
The Symbolic Processing course, which had 16 undergraduate students, met last spring, not long after David Fincher's Zodiac film reignited nationwide interest in the case. Garlick decided to capitalize on that interest by asking the class to work on solving the 340-cipher.
The Zodiac killer was a serial killer in northern California who sent taunting letters to the media and police in the late 1960s. His identity remains unknown today.
A documentary crew heard about the class's work on the Internet and asked Garlick to fly to London last summer for on-camera interviews.
The documentary took a look at famous codes and ciphers, the people who make and crack the codes, how they are solved and why codes are needed.
Code experts believe the 340-cipher hasn't been solved yet for one of two reasons: the Zodiac killer meant it as a hoax and the code is meaningless, or the code requires some manipulation before it can be solved. For example, some think it needs to be cut into pieces and rearranged before it can be solved.
Despite not cracking the infamous code, Garlick says the students loved the challenge.
"It captivated the students," he says. "This is definitely something I may do in another class because it was such a fun way to teach computer science."
Sarah Bahari with UNT News Service can be reached at Sarah.Bahari@unt.edu.