An amateur says he finally cracked the Zodiac Killer mystery. Longtime sleuths say he's an 'egomaniac' who can't prove it.

• A French business consultant said he spent two weeks solving the Zodiac Killer's final ciphers.
• The online community of internet Zodiac sleuths is annoyed at his ego.
• Three Zodiac experts told Insider the solutions don't make sense and are impossible to prove.

In the online community of Zodiac Killer sleuths, it's not unusual for strangers to pop up out of nowhere and proclaim to tens of thousands of users that they've cracked the decades-old mystery.

So in January, when a French business consultant named Fayçal Ziraoui proudly announced his solutions to the as-of-yet-unsolved ciphers, longtime Zodiac buffs were skeptical and dismissive.

Ziraoui is far from the only amateur to hunker down and attempt to crack the codes, but his solutions have picked up international media attention in recent weeks and months, culminating in a June 22 New York Times article describing his efforts and the pushback he's received from the online community.

"This poor guy is such an egomaniac that he thinks he's going to spend a little bit of time and solve a 52-year-old case using smoke and mirrors," Tom Voigt, the webmaster of the popular zodiackiller.com who has been investigating the murders himself for 25 years, told Insider.

Voigt said he fields roughly 500 emails each week, mostly from "lunatics" claiming to have solved the case. At least 10 of those emails contain code solutions just like Ziraoui's, he said.

"The more things change, the more they stay the same," Voigt said. "This isn't the first guy - it's just the latest. Next week there'll be somebody else."

The Zodiac Killer is believed to have killed at least five people in the late 1960s in the San Francisco Bay area, and was never caught. The killer sent the media a number of taunting letters, including four ciphers written in code. One cipher was solved back in the 60s, another was solved last year, and two remain a mystery.

The online Zodiac community says the remaining ciphers are currently impossible to prove

Insider spoke with three Zodiac Killer experts, including Voigt, who expressed surprise that The Times had run with Ziraoui's claims. Though the experts said they were open to being proved wrong, all were skeptical of Ziraoui's methods.

The Zodiac Killer's final two ciphers, known as Z13 and Z32, are what Ziraoui claims to have cracked after two weeks of obsessive and sleepless labor.

Ziraoui said he believes the answer to Z32 is "LABOR DAY FIND 45.069 NORT 58.719 WEST," a possible reference to coordinates leading to a school in the California city of South Lake Tahoe. He said Z13 - which is widely believed to contain the name of the killer - can be translated to "KAYR," a misspelled reference to Lawrence Kaye, a man who was previously named as a suspect and died in 2010.

There are two problems with Ziraoui's solutions, the experts said, one of them being Ziraoui appears to have manipulated his results to fit the answer he was looking for.

Ziraoui's assumption that "KAYR" was simply an erroneous reference to the name "Kaye" immediately turned off Mike Morford, a true crime writer who runs zodiackillersite.com.

"He's changing a word to match a suspect," Morford said. "He just saw a four-letter word with a 'K,' switched it to what he thought it was and went with it. From everything I know about ciphers… you don't jam stuff in there. You let it come out, let the message pop out on its own."

The second problem the experts identified was that even if Ziraoui's answers are correct, there's currently no way to prove it.

"The shorter a cipher is, the fewer opportunities there are to find repeated patterns," said Michael Butterfield, who runs zodiackillerfacts.com and has worked as a consultant on Zodiac-related movies, documentaries, and articles.

Z13 and Z32 contain 13 and 32 characters, respectively, so Butterfield said there are thousands of potential outcomes and no way to prove one is more correct than the others.

It's not unthinkable that an amateur could crack the ciphers. It happened just last year, when an international team of three private citizens produced an answer to Z340, which the FBI later confirmed was accurate. But Zodiac experts say Z32 and Z13 are far too short to determine with certainty.

Z340 and Z408, the cipher that was solved in the 60s, were both lengthy enough to reveal helpful letter pairings like "TH" or "LL" that could be found in the words "that," "will," "all," and "death."

The experts told Insider Ziraoui's answers so far reveal much more about him than they do about the Zodiac Killer.

"It takes tremendous ego to think that you've accomplished something that other people, hundreds of hundreds of people, have been trying to accomplish for decades," Butterfield said. "And an especially large ego to make that claim based on virtually nothing, or really slim evidence that is heavily subject to interpretation."