Three private code-breakers from the US, Australia and Belgium have deciphered one of the ciphers by the infamous Zodiac killer.
It took 51 years for the "340 Cipher" to be solved, after it was sent to the San Francisco Chronicle on November 8, 1969.
The cipher, which got its name from the number of characters and symbols in it, had remained a mystery for decades but the FBI has confirmed the code has now been deciphered.
"Last weekend, a team I'm on solved the 340 and submitted it to the FBI," spokesperson David Oranchak told the San Francisco Chronicle.
"They have confirmed the solution. No joke! This is the real deal."
More than five decades later, we know now what "Cipher 340" said:
"I hope you are having lots of fun in trying to catch me - that wasn't me on the tv show - which brings up a point about me - I am not afraid of the gas chamber because it will send me to paradise all the sooner because I now have enough slaves to work for me where everyone else has nothing when they reach paradise - so they are afraid of death - I am not afraid because I know that my new life is life will be an easy one in paradise death."
It is believed the killer is referring to a TV appearance in October 1969, when a man who claimed to be the Zodiac Killer called a talk show in the US.
The Zodiac Killer is known to have murdered at least five people in the northern California area, in the late 1960s and early 1970s. The number is not certain though, as he once claimed responsibility for the death of at least three dozen people.
The FBI has confirmed the cipher has been decoded.
It is the second of the killer's four ciphers to be solved.
"The Zodiac Killer terrorised multiple communities across Northern California and even though decades have gone by, we continue to seek justice for the victims of these brutal crimes," FBI spokesperson Cameron Polan told the San Francisco Chronicle.
"Due to the ongoing nature of the investigation, and out of respect for the victims and their families, we will not be providing further comment at this time."
"Cipher 340" was solved by Sam Blake (Australia), Jarl Van Eycke (Belgium), and David Oranchak (US). It took the team two days to crack the code, which they then sent to the FBI, on December 5.