Top 10 Unsolved Mysteries That Still Haunt Investigators

Between 1968 and 1969, the Zodiac Killer murdered at least five people in Northern California and sent taunting letters and cryptograms to newspapers. He was never identified. The case consumed the San Francisco Police Department for decades. In 2020, a team of codebreakers finally cracked the 340 cipher (sent in 1969), which read: "I hope you are having lots of fun in trying to catch me... I am not afraid of the gas chamber because it will send me to paradice." The 408 cipher was cracked in 1969. The Z13 cipher (containing his real name, he claimed) remains unsolved. The case has generated more amateur investigation than any crime in American history.

On March 8, 2014, a Boeing 777 carrying 239 people vanished. MH370 is the greatest aviation mystery of the modern era — a plane with 600,000 pounds of metal, tracked by radar and satellite, disappeared into the Indian Ocean and has never been found despite the most expensive search in aviation history ($200 million+). Only three confirmed debris fragments have washed ashore in the western Indian Ocean. The final satellite "handshake" data narrowed the crash zone, but 46,000 square miles of ocean floor were searched without finding the main wreckage. In 2024, Ocean Infinity proposed a new search using autonomous underwater vehicles.

In the autumn of 1888, at least five women were murdered in the Whitechapel district of London with a level of surgical precision that suggested medical knowledge. "Jack the Ripper" — named after a letter sent to a news agency (likely a hoax) — was never caught. The case has generated over 100 suspects in academic literature, including a royal physician, a Polish immigrant, and Lewis Carroll. DNA evidence in 2019 pointed to Aaron Kosminski, a Polish barber, but the methodology was challenged by geneticists. 137 years later, the case remains open. More books have been written about the Ripper than any other criminal in history.

On December 1, 1948, an unidentified man was found dead on Somerton Beach in Adelaide, Australia. He carried no identification. All clothing labels had been removed. A scrap of paper in a hidden pocket read "Taman Shud" ("ended" in Persian), torn from a rare edition of The Rubaiyat of Omar Khayyam. The book was found in a car nearby, containing an uncracked code written in pencil. The man was never identified despite international inquiries. In 2022, DNA analysis and genealogy identified him as Carl "Charles" Webb, a Melbourne electrical engineer — but why he was on the beach, how he died, and what the code means remain unknown.

A 240-page book written in an unknown script with illustrations of unidentifiable plants, astronomical diagrams, and naked women in strange bathing pools. Carbon-dated to the early 15th century, the Voynich Manuscript has defeated every codebreaker who has attempted it — including NSA cryptanalysts, AI language models, and academic linguists. The script has consistent statistical properties suggesting it's a real language (not random), but no one can read it. Theories range from a medieval hoax to a lost language to an elaborate cipher. It's housed at Yale University's Beinecke Library. 600 years of mystery.

In February 1959, nine experienced hikers died in the Ural Mountains of the Soviet Union under inexplicable circumstances. They cut their way out of their tent in the middle of the night, fled into -30C temperatures in minimal clothing, and scattered. Some had massive internal injuries with no external trauma. One woman was missing her tongue. Soviet investigators concluded the cause was "a compelling natural force." In 2019, Swiss researchers used avalanche simulations to propose a delayed slab avalanche as the trigger — the most scientifically rigorous explanation so far, though not universally accepted. 65 theories have been published.

On July 30, 1975, Teamsters President Jimmy Hoffa — possibly the most powerful labor leader in American history — went to a restaurant in suburban Detroit to meet two Mafia figures and was never seen again. The FBI has investigated for 50 years, excavated multiple locations (including under Giants Stadium in New Jersey — he wasn't there), and interviewed hundreds of mobsters. The leading theory: he was killed by the Mafia to prevent him from reclaiming the Teamsters presidency, which organized crime controlled. His body has never been found. He was declared legally dead in 1982. The phrase "buried next to Hoffa" entered American slang.

An encrypted sculpture standing in the courtyard of CIA headquarters in Langley, Virginia since 1990. Artist Jim Sanborn embedded four encrypted messages into the copper panels. Three have been solved (by a CIA analyst in 1998 and independently by a computer scientist). The fourth section — 97 characters known as K4 — remains unsolved after 35 years, despite being attempted by the NSA, CIA, and thousands of amateur cryptanalysts. Sanborn has released clues over the years: characters 64-69 spell "BERLIN," characters 70-74 spell "CLOCK." In 2020, he confirmed the next word is "NORTHEAST." The rest is unknown. The CIA's own puzzle, in their own courtyard, that they can't solve.

On August 15, 1977, Ohio State University's Big Ear radio telescope detected a 72-second narrowband radio signal from the direction of the constellation Sagittarius that was 30 times stronger than background noise. Astronomer Jerry Ehman circled the printout and wrote "Wow!" in the margin. The signal has never repeated despite hundreds of subsequent observations of the same region. It matched the expected signature of an extraterrestrial transmission on the hydrogen line (1420 MHz). A 2017 study proposed a comet as the source, but this was disputed. If it was natural, we've never found the mechanism. If it wasn't natural, we've never heard from them again.

Between 1968 and 1969, the Zodiac Killer murdered at least five people in Northern California and sent taunting letters and cryptograms to newspapers. He was never identified. The case consumed the San Francisco Police Department for decades. In 2020, a team of codebreakers finally cracked the 340 cipher (sent in 1969), which read: "I hope you are having lots of fun in trying to catch me... I am not afraid of the gas chamber because it will send me to paradice." The 408 cipher was cracked in 1969. The Z13 cipher (containing his real name, he claimed) remains unsolved. The case has generated more amateur investigation than any crime in American history.

On March 8, 2014, a Boeing 777 carrying 239 people vanished. MH370 is the greatest aviation mystery of the modern era — a plane with 600,000 pounds of metal, tracked by radar and satellite, disappeared into the Indian Ocean and has never been found despite the most expensive search in aviation history ($200 million+). Only three confirmed debris fragments have washed ashore in the western Indian Ocean. The final satellite "handshake" data narrowed the crash zone, but 46,000 square miles of ocean floor were searched without finding the main wreckage. In 2024, Ocean Infinity proposed a new search using autonomous underwater vehicles.

In the autumn of 1888, at least five women were murdered in the Whitechapel district of London with a level of surgical precision that suggested medical knowledge. "Jack the Ripper" — named after a letter sent to a news agency (likely a hoax) — was never caught. The case has generated over 100 suspects in academic literature, including a royal physician, a Polish immigrant, and Lewis Carroll. DNA evidence in 2019 pointed to Aaron Kosminski, a Polish barber, but the methodology was challenged by geneticists. 137 years later, the case remains open. More books have been written about the Ripper than any other criminal in history.

On December 1, 1948, an unidentified man was found dead on Somerton Beach in Adelaide, Australia. He carried no identification. All clothing labels had been removed. A scrap of paper in a hidden pocket read "Taman Shud" ("ended" in Persian), torn from a rare edition of The Rubaiyat of Omar Khayyam. The book was found in a car nearby, containing an uncracked code written in pencil. The man was never identified despite international inquiries. In 2022, DNA analysis and genealogy identified him as Carl "Charles" Webb, a Melbourne electrical engineer — but why he was on the beach, how he died, and what the code means remain unknown.

A 240-page book written in an unknown script with illustrations of unidentifiable plants, astronomical diagrams, and naked women in strange bathing pools. Carbon-dated to the early 15th century, the Voynich Manuscript has defeated every codebreaker who has attempted it — including NSA cryptanalysts, AI language models, and academic linguists. The script has consistent statistical properties suggesting it's a real language (not random), but no one can read it. Theories range from a medieval hoax to a lost language to an elaborate cipher. It's housed at Yale University's Beinecke Library. 600 years of mystery.

In February 1959, nine experienced hikers died in the Ural Mountains of the Soviet Union under inexplicable circumstances. They cut their way out of their tent in the middle of the night, fled into -30C temperatures in minimal clothing, and scattered. Some had massive internal injuries with no external trauma. One woman was missing her tongue. Soviet investigators concluded the cause was "a compelling natural force." In 2019, Swiss researchers used avalanche simulations to propose a delayed slab avalanche as the trigger — the most scientifically rigorous explanation so far, though not universally accepted. 65 theories have been published.

On July 30, 1975, Teamsters President Jimmy Hoffa — possibly the most powerful labor leader in American history — went to a restaurant in suburban Detroit to meet two Mafia figures and was never seen again. The FBI has investigated for 50 years, excavated multiple locations (including under Giants Stadium in New Jersey — he wasn't there), and interviewed hundreds of mobsters. The leading theory: he was killed by the Mafia to prevent him from reclaiming the Teamsters presidency, which organized crime controlled. His body has never been found. He was declared legally dead in 1982. The phrase "buried next to Hoffa" entered American slang.

An encrypted sculpture standing in the courtyard of CIA headquarters in Langley, Virginia since 1990. Artist Jim Sanborn embedded four encrypted messages into the copper panels. Three have been solved (by a CIA analyst in 1998 and independently by a computer scientist). The fourth section — 97 characters known as K4 — remains unsolved after 35 years, despite being attempted by the NSA, CIA, and thousands of amateur cryptanalysts. Sanborn has released clues over the years: characters 64-69 spell "BERLIN," characters 70-74 spell "CLOCK." In 2020, he confirmed the next word is "NORTHEAST." The rest is unknown. The CIA's own puzzle, in their own courtyard, that they can't solve.

On August 15, 1977, Ohio State University's Big Ear radio telescope detected a 72-second narrowband radio signal from the direction of the constellation Sagittarius that was 30 times stronger than background noise. Astronomer Jerry Ehman circled the printout and wrote "Wow!" in the margin. The signal has never repeated despite hundreds of subsequent observations of the same region. It matched the expected signature of an extraterrestrial transmission on the hydrogen line (1420 MHz). A 2017 study proposed a comet as the source, but this was disputed. If it was natural, we've never found the mechanism. If it wasn't natural, we've never heard from them again.