Home » By Region » Global History » From Ancient Enigmas to Modern Secrets: 13 Unresolved Historical Mysteries

From Ancient Enigmas to Modern Secrets: 13 Unresolved Historical Mysteries

Image of one of the great mysteries of history, Stonehenge, on the Salisbury Plain in England
One of the great mysteries of history, Stonehenge, in Wiltshire, England

Roll up your sleeves, dust off your Sherlock Holmes cap, and get ready for a riveting journey through the annals of history. We’re about to dive headfirst into the intriguing world of history’s unsolved mysteries, a realm of enigmas and conundrums that have baffled scholars and history enthusiasts alike for centuries.

From the cryptic codes of ancient civilizations to baffling disappearances and unexplained phenomena, these mysteries listed below are a testament to the tantalizing secrets that our past holds in its depths.

Fascinating historical mysteries from 587 BC to present day

  • The Disappearance of the Indus Valley Civilization (around 1900 BC)
  • Stonehenge (construction between 3000 BC to 2000 BC)
  • The Shroud of Turin (alleged 1st Century AD)
  • The Lost Colony of Roanoke (1587)
  • The Voynich Manuscript (15th century)
  • The Mary Celeste (1872)
  • Jack the Ripper (late 19th century)
  • The Disappearance of Amelia Earhart (1937)
  • The Bermuda Triangle (reported incidents primarily 20th century)
  • The Loch Ness Monster (reported sightings since the 1930s)
  • The Taos Hum (reported since the early 1990s)

But why, you might ask, should we delve into these mysteries?

Well, the answer lies not only in their captivating inexplicability but also in the potential of unearthing revelations that could dramatically alter our understanding of history.

The allure of these mysteries is exhilarating, promising a thrilling journey that weaves together science, history, and the insatiable human curiosity.

So, buckle up, as we embark on an unforgettable odyssey to uncover the captivating complexities of our shared past.

13 Great Mysteries of History Listed

The first historical mystery on our list needs little introduction, especially due to its high-profile exposure in the fictional 1981 film Raiders of the Lost Ark.

While the story told in the movie wasn’t based in reality, the Ark of the Covenant itself was. Read on to see what it’s all about.

Image of a stained glass window showing two individuals carrying the Ark of the Covenant

1. The Fate of the Ark of the Covenant

The Ark of the Covenant, also known as the Ark of the Testimony, is one of the most illustrious artifacts in biblical history.

Described in the Book of Exodus, it was a gilded wooden chest that housed the two stone tablets on which the Ten Commandments were inscribed.

The ark was also said to contain Aaron’s rod and a golden pot of manna.

It was considered the physical manifestation of God’s presence on Earth and was carried by the Israelites during their 40 years of wandering in the desert.

The mystery surrounding the Ark of the Covenant primarily revolves around its disappearance.

The last historical mention of the Ark in the Bible is in the Book of Jeremiah, where it is said to have been in the First Temple in Jerusalem.

However, when the Babylonians sacked Jerusalem and destroyed the temple in 586 BC, there was no record of the Ark being among the items taken or destroyed.

This has led to much speculation about what happened to this sacred artifact.

Various theories have been proposed about the Ark’s final resting place.

Some suggest it was hidden by the prophet Jeremiah or King Josiah before the Babylonians invaded. In contrast, others believe it was taken to Ethiopia, where it resides today in the Church of St. Mary of Zion.

Yet, despite numerous supposed sightings and searches, the whereabouts of the Ark of the Covenant remains one of the greatest unsolved mysteries in biblical archaeology.

Its disappearance continues to captivate historians, archaeologists, and religious scholars around the globe, adding yet another layer of intrigue to this already enigmatic historical artifact.

Image of a river in the Indus valley in Pakistan, home of one of the great mysteries of histort, the disappearance of the Indus River Valley civilization
The Giglit River in modern-day Pakistan, a tributary to the Indus River

2. The Disappearance of the Indus Valley Civilization

The Indus River Valley Civilization, also known as the Harappan Civilization, was one of the world’s earliest urban civilizations, existing from 3300 BC to 1300 BC.

Located in the northwestern regions of South Asia, primarily in present-day Pakistan and India, it comprised over five million inhabitants at its peak, known for its impressive city-planning, advanced sanitation systems, and an enigmatic script that remains undeciphered to this day.

The civilization was extremely sophisticated, with settlements like Mohenjo-Daro and Harappa showcasing intricate brickwork, efficient water management systems, and standardized weights and measures.

Mysteriously, around 1900 BC, this advanced civilization began to decline, and by 1300 BC, it had completely disappeared.

The exact reasons for the demise of the Indus Valley Civilization remain a matter of speculation among historians and archaeologists, contributing to its aura as one of history’s unsolved mysteries.

Some theories suggest that changes in the course of the river, which was the lifeline of the civilization, could have led to a severe drought, causing the civilization to collapse.

Others propose that a massive earthquake or a series of floods might have led to the abandonment of the cities.

Another intriguing theory is the Aryan Invasion Theory, which suggests that the civilization was overrun by a nomadic, Indo-European tribe known as the Aryans.

However, this theory has been largely discredited due to a lack of archaeological evidence. It’s also speculated that internal social and political issues could have led to its downfall.

Despite the multitude of theories, the disappearance of the Indus Valley Civilization remains a profound mystery, with no consensus among scholars, making it a fascinating subject for historical exploration and study.

Image of the historical mystery, Stonehenge, in Wilshire, England
Perhaps the greatest of all the great mysteries of history, Stonehenge, in England

3. Stonehenge

Stonehenge, located in southern England, is a prehistoric monument that has fascinated scholars and visitors alike for centuries.

The construction of this architectural marvel spanned approximately 1500 years, with work commencing in around 3000 BCE and concluding around 1520 BCE.

The monument was erected in stages: the initial stage involved the digging of a circular ditch and bank, possibly accompanied by a ring of timber posts.

In the second stage, non-indigenous bluestones were arranged in a horseshoe or circular formation.

The final stage saw the assembly of large sandstone slabs into an outer crescent or ring, with some forming trilithons in the center.

The origin of Stonehenge’s stones adds an intriguing layer to its history.

The larger sarsen stones are believed to have been sourced from a quarry about 25 miles away. In contrast, the smaller bluestones have been traced back to Wales, a staggering 200 miles away.

How these stones were transported over such vast distances remains a mystery.

Theories suggest methods ranging from sledges and rafts to natural glacial movements, but there is no universally accepted explanation.

The purpose of Stonehenge is another enduring mystery.

Although widely believed to have been a burial ground, other theories suggest it could have served as a meeting place, an astronomical “computer,” or a monument to the ancestral dead.

Despite various speculations, including the fanciful notion of extraterrestrial involvement, its exact purpose remains unclear.

What is certain is that Stonehenge, a designated UNESCO World Heritage site, stands as a testament to the ingenuity of our Neolithic ancestors and continues to captivate us with its unresolved mysteries.

Image of the Duomo di Torino, the home of the Shroud of Turin
The Duomo di Turin in Italy, home of the Shroud of Turin, one of the great mysteries of history

4. The Shroud of Turin

The Shroud of Turin, a linen cloth bearing the image of a man who appears to have suffered physical trauma in a manner consistent with crucifixion, is one of the most revered religious artifacts and also one of the most contentious.

The shroud, measuring approximately 4.4 by 1.1 meters, is kept in the royal chapel of the Cathedral of Saint John the Baptist in Turin, Italy.

The image on the shroud is much clearer in black-and-white negative than in its natural sepia color, a characteristic that many find intriguing.

The shroud is associated with Jesus Christ, with many believers asserting that it was the burial cloth in which Jesus was wrapped after his crucifixion.

However, the Shroud of Turin has been steeped in controversy, with its authenticity continually debated.

The primary point of contention arises from conflicting scientific tests.

Carbon-14 dating conducted in 1988 by three separate laboratories concluded that the cloth was produced between 1260 and 1390 AD, implying it could not be the burial shroud of Jesus.

On the other hand, subsequent research challenged these findings, citing the possibility that the tested fragments could be from a later repair rather than the original cloth.

The controversy surrounding the Shroud of Turin’s authenticity has only added to its intrigue and significance for many.

Despite the uncertainty, it continues to be an object of veneration and pilgrimage for countless people around the world.

It’s also an important artifact in the study of medieval Christian art, given the unique three-dimensional image on the cloth.

Whether a medieval forgery or the actual burial shroud of Christ, the Shroud of Turin captures the imagination of believers and skeptics alike.

Image of a stamp commemorating the voyages that established the Roanoke colony in North Carolina
A 1984 U.S. stamp commemorating the 400th Anniversary
of the voyages to the Roanoke colony in North Carolina

5. The Lost Colony of Roanoke

The Lost Colony of Roanoke, established in 1587, was an English settlement located on Roanoke Island, off the coast of present-day North Carolina.

The colony was financed and organized by Sir Walter Raleigh, an English adventurer and writer, although he himself never set foot in it.

The colony consisted of over 100 settlers, including men, women, and children, led by Governor John White.

White returned to England later that year for supplies, leaving behind the fledgling colony, including his own daughter and granddaughter, Virginia Dare, the first English child born in the New World.

When White returned to Roanoke in 1590, three years after his departure, he found the colony completely abandoned with no trace of the settlers.

The only clue left was the word “CROATOAN” carved into a wooden post and “CRO” etched into a tree.

Despite the mystery surrounding the disappearance, no serious search was made for the settlers, and their fate remains one of the enduring mysteries of American history.

Many theories have been proposed to explain the colonists’ disappearance, ranging from violent massacres to integration with nearby Native American tribes.

Some suggested they may have tried to sail back to England on their own and got lost at sea.

In recent years, archaeological investigations and scientific studies have provided some clues, but the mystery of what happened to the Lost Colony of Roanoke continues to captivate historians, researchers, and the public alike.

Image of one of the great mysteries of history, the Voynich Codex
Pages from one of the great mysteries of history, the Voynich
Manuscript, currently housed at Yale University in New Haven, Connecticut

6. The Voynich Manuscript

The Voynich Manuscript, often hailed as the world’s most mystifying book, is a 15th or 16th-century codex that has puzzled scholars for centuries.

The text is written in an unidentifiable script, and its author remains a mystery.

The manuscript is renowned for its illustrations that encompass botanical, astronomical, and scientific subjects, featuring unidentifiable plants, astronomical charts, and pharmaceutical herbs.

The manuscript’s historical ownership is also a matter of debate.

However, it is generally accepted that Emperor Rudolph II of Germany, who reportedly purchased it from the English astrologer John Dee, was once its owner.

In 1912, the manuscript was acquired by Wilfrid M. Voynich, after whom it is named, and later donated to the Beinecke Library.

Despite countless attempts to decipher the text, the Voynich Manuscript remains a mystery.

Various theories have been proposed, and numerous books written about it, but the contents and the unique script remain undeciphered, fueling the public’s fascination and curiosity.

The manuscript’s enigmatic origin and elusive meaning continue to excite scholars, historians, and enthusiasts, making it one of the most intriguing historical artifacts of our time.

Image of a painting of the Mary Celeste under sail
Painting of the Mary Celeste underway (c. 1861), the subject of the unsolved
historical mystery related to the disappearance of its passengers and crew

7. The Mary Celeste

The Mary Celeste was an American-registered merchant brigantine recognized for its perplexing mystery.

Discovered adrift and deserted in the Atlantic Ocean off the Azores in 1872 by the British brig Dei Gratia, its state was puzzling.

The ship was found with three and a half feet of water in its bottom, one of its two pumps disassembled, and its only lifeboat missing.

Yet, surprisingly, the cargo was largely intact, with enough food and water for six months.

The mysterious part of the Mary Celeste narrative is the inexplicable disappearance of the ten people who were aboard the ship.

Various hypotheses, including mutiny, pirate attacks, and even sea monsters, were proposed to account for the disappearance, but none of them were conclusive.

The fate of the vanished crew and passengers of the Mary Celeste remains one of the most baffling tales in the maritime world, fueling public fascination and curiosity similar to the Lost Colony of Roanoke and the enigmatic Voynich Manuscript.

A recent investigation using modern technology and newly discovered documents has tried to piece together a plausible scenario of what happened.

The investigation dismissed theories of sea monsters and pirates and suggested that alcohol consumption onboard leading to mutiny was unlikely.

The most plausible explanation put forward was that the ship’s red oak barrels were leaking, which might have prompted the crew to abandon the ship.

Despite this, the mystery continues to intrigue, as the investigation highlighted the limitations of historical cases and the challenges in drawing definitive conclusions.

Replica case records of Jack the Ripper’s victims
(Note: Red coloring is just for effect)

8. Jack the Ripper

Jack the Ripper is an infamous figure in criminal history, known for his brutal and gruesome murders in the late 19th century.

He terrorized the Whitechapel district of London’s East End in 1888, killing at least five women and mutilating their bodies in an unusual manner that suggested a significant understanding of human anatomy.

These murders all took place within a mile of each other, from August 7 to September 10, 1888, leading investigators to believe they were the work of the same individual, who also came to be referred to as “Leather Apron”.

The mystery of Jack the Ripper’s identity heightened with the circulation of several letters allegedly sent by the killer to the London Metropolitan Police Service, also known as Scotland Yard.

These letters taunted officers about his heinous acts and hinted at future murders.

The name “Jack the Ripper” originates from one of these letters, which some believe might have been a hoax.

Despite numerous investigations and claims of definitive evidence, the killer’s identity and motives remain shrouded in mystery.

Over the years, various theories about the Ripper’s identity have surfaced, with more than 100 suspects named since 1888.

Some of these suspects include renowned Victorian painter Walter Sickert, a Polish migrant, and even a grandson of Queen Victoria.

In a recent development, a shawl found by the body of Catherine Eddowes, one of the Ripper’s victims, has been used in an attempt to identify the killer as Aaron Kosminski, a 23-year-old Polish barber living in London.

However, the mystery continues to fuel intrigue and speculation, becoming a key part of crime folklore and entertainment.

Image of the subject of one of the great mysteries of history, Amelia Earhart
Amelia Earhart, the subject of one of the great mysteries of history that still goes unsolved

9. The Disappearance of Amelia Earhart

Amelia Earhart, born in Kansas in 1897, was a pioneering figure in aviation and a strong advocate for women’s rights.

With a passion for adventure and a determination to challenge gender norms, she emerged as the first female aviator to fly solo across the Atlantic Ocean.

Her successful flights and numerous records made her an international icon, inspiring countless women to pursue their ambitions in a male-dominated field.

Apart from her aviation accomplishments, Earhart was also a published writer, offering insights into her experiences in the air and her perspectives on women’s roles in society.

Earhart’s ambition culminated in an audacious plan in 1937: a global flight that would make her the first woman to circumnavigate the globe.

She and her navigator, Fred Noonan, embarked on this ambitious journey in a modified Lockheed Electra.

The flight was going smoothly until they reached the Pacific leg of their journey.

While attempting to locate Howland Island, a tiny piece of land in the vast Pacific, Earhart and Noonan lost radio contact and subsequently disappeared.

Despite extensive search efforts from the U.S. government, no trace of Earhart, Noonan, or their plane was ever found, leading to their declared loss at sea.

Various theories about her disappearance emerged, the official one suggesting they ran out of fuel and crashed into the ocean.

Other speculations ranged from Earhart being taken prisoner by the Japanese to landing on an uninhabited island.

To this day, the mystery of Amelia Earhart’s disappearance remains unsolved, adding to her enduring legacy in aviation history.

Image of a map with the area known as the Bermuda Triangle under a magnifying glass
One of the great historical mysteries, the Bermuda Triangle

10. The Bermuda Triangle

The Bermuda Triangle, also known as the Devil’s Triangle, is an area located in the western part of the North Atlantic Ocean.

This region, roughly bounded by Miami, Bermuda, and Puerto Rico, has gained notoriety due to the mysterious disappearances of numerous ships and airplanes, with reports dating back to the 19th century.

The term ‘Bermuda Triangle’ gained traction after strange occurrences were reported during Christopher Columbus’s voyage, though it didn’t capture the public’s attention until the 20th century.

The Triangle has been the subject of many supernatural theories to explain the disappearance of aircraft and sea vessels within its boundaries.

These theories range from extraterrestrial activity and the lost continent of Atlantis to magnetic anomalies and sea vortices.

Notable incidents include the sinking of the USS Cyclops in 1918 and the disappearance of five Navy bombers in 1945, further fueling the enigmatic reputation of the area.

Despite these theories and incidents, both the U.S. Navy and the U.S. Coast Guard assert that there are no supernatural explanations for these incidents.

The National Oceanic and Atmospheric Administration states that there is no evidence to suggest the frequency of disappearances in the Bermuda Triangle is higher than in any other well-traveled parts of the ocean.

More plausible explanations involve geophysical and environmental factors such as navigational errors, tropical storms and hurricanes, rogue waves, and the Gulf Stream.

Image of Loch Ness, home of the historical mystery of the Loch Ness Monster or Nessie
Loch Ness, in Scotland, home of one of the great
mysteries of history, Nessie, or the Loch Ness Monster

11. The Loch Ness Monster

The Loch Ness Monster, affectionately known as “Nessie”, is a creature believed to inhabit the Loch Ness in the Scottish Highlands.

The first reported sighting of Nessie dates back to the 6th century in the biography of Saint Columba, where it was said that he saved a man from the beast.

However, modern interest in the creature was sparked in the 1930s after a photograph, known as the “Surgeon’s Photograph”, purported to show the monster’s head and neck, was published.

The existence of Nessie has been a topic of controversy and debate for decades. Skeptics dismiss the sightings as misidentifications of common objects and animals such as logs, otters, or bird wake.

Others suggest they are optical illusions caused by the loch’s changing conditions.

The infamous “Surgeon’s Photograph” was later revealed to be a hoax, further fueling skepticism.

Despite the lack of concrete evidence, the Loch Ness Monster has become a cultural phenomenon, attracting tourists from around the world.

Numerous expeditions have been launched to find Nessie, employing everything from sonar to submarines.

However, none have produced definitive proof of the creature’s existence.

Scientists argue that the loch’s harsh conditions and limited food supply make it unlikely for a large creature like Nessie to survive.

Yet, the legend persists, fueled by occasional sightings and unexplained sonar readings.

Image of a police composite drawing of a Zodiac Killer suspect
Police drawing of the Zodiac Killer

12. The Mystery of the Zodiac Killer

The Zodiac Killer is one of the most infamous serial killers in American history, whose crimes dominated headlines in the late 1960s and early 1970s.

This unknown criminal operated in Northern California, mainly in the San Francisco Bay Area.

The Zodiac Killer’s identity remains a mystery, but his legend is defined by the terror he instilled, his taunting letters to the press, and the complex cyphers he included in his communications, few of which have been definitively solved.

The investigation into the Zodiac Killer began after the murders of four men and three women between the ages of 16 and 29, which occurred between December 1968 and October 1969.

The Zodiac Killer would callously send letters to local newspapers, claiming responsibility for the murders and taunting authorities with cryptic messages and ciphers.

The killer’s moniker was derived from a series of cryptograms included in these letters, which were signed ‘Zodiac.’

Despite extensive efforts by authorities, the killer’s brazen acts of violence and psychological warfare left the investigators stumped and the public petrified.

The case of the Zodiac Killer has remained open for over five decades, with detectives both professional and amateur taking a crack at deciphering the killer’s cryptic codes and uncovering his identity.

While several suspects have been named over the years, no one has ever been officially charged with the crimes.

The Zodiac case remains one of the most chilling unsolved mysteries in the annals of American crime, a symbol of the fear and frustration that can result when a killer remains not just unpunished, but unidentified.

Image of the mountains near Taos, New Mexico
Taos, New Mexico, home of the famous hum and the historical mystery surrounding it

13. The Taos Hum

The Taos Hum is a mysterious and unexplained low-frequency humming noise that has puzzled the inhabitants and researchers of Taos, a small town in New Mexico, for years.

The hum, often compared to the sound of an idling diesel truck or high-powered bass audio, has been reported by approximately two percent of the town’s population.

Despite numerous investigations into the phenomenon, no identifiable cause or source has been found, fueling a variety of theories ranging from UFOs to government experiments.

Scientific investigations into the Taos Hum have been extensive but have largely ruled out external sources such as the power grid, seismic activity, and even US Navy ELF stations.

These investigations have led to intriguing findings, however.

Diverse accounts from different listeners suggest that not everyone is hearing the same sound.

This has led some researchers to propose that the hum may not be an external sound at all, but rather, a result of some sort of inner personal experience or auditory hallucination.

Despite the lack of concrete evidence or explanations, the Taos Hum continues to be a source of mystery and fascination.

Some researchers suggest that the hum could be a product of spontaneous otoacoustic emissions, where the ears generate their own noises, commonly noticeable in quiet environments or when one is paying close attention.

Although this theory has not been definitively proven, it adds another layer to the enigmatic puzzle of the Taos Hum.

As it stands, the Taos Hum remains an intriguing unsolved mystery, echoing in the ears of a select few and confounding scientists and researchers alike.

Image of old books possibly containing information on great historical mysteries

Wrap-up: 13 Great Mysteries of History

In conclusion, the mysteries of history are a testament to the unending curiosity and investigative spirit of humankind.

They serve as reminders that despite our advancements in technology, science, and understanding, there is still much about our world and our past that remains elusive and unknown.

From the enigmatic Zodiac Killer to the puzzling Taos Hum, these mysteries continue to captivate our imaginations, stir our intrigue, and inspire us to keep seeking answers.

What makes these mysteries so captivating is not just their inherent enigma, but also the myriad of interpretations and theories they spawn.

They open a window into our collective psyche, revealing our fascination with the unknown, our fear of the inexplicable, and our relentless pursuit of truth.

These mysteries, be they unsolved crimes, unexplained phenomena, or enigmatic historical events, continue to be a source of inspiration for numerous books, films, and research.

Finally, these 13 great mysteries of history remind us that the world is far more complex and intriguing than we often give it credit for.

As we continue to dig deeper, explore further, and question more, we can only hope to uncover the truth behind these enduring enigmas.

But until then, they will remain as tantalizing puzzles, challenging us to think, question, and explore, thereby keeping the flame of curiosity alive in our hearts and minds.

Image of the second temple in Jerusalem
The Second Temple in Jerusalem, built on the site of the original temple
where the Ark of the Covenant was previously housed about 2,500 years ago

FAQs: Great Mysteries of History

1. What percentage of people can hear the Taos Hum?

Estimates suggest that only about 2% of the population in areas where the Taos Hum is heard can actually detect the sound.

This small percentage of people, often referred to as “hearers” or “hummers,” report experiencing it at varying degrees of intensity.

This inconsistency, coupled with the lack of a concrete source, adds to the mystery and intrigue of the Taos Hum.

2. What is the meaning of “CROATOAN” from the Lost Colony of Roanoke historical mystery?

“CROATOAN” is a significant clue in the mystery of the “Lost Colony” of Roanoke.

This word was found carved into a palisade when Governor John White returned to the colony in 1590 and found it abandoned.

The term “CROATOAN” was the name of an island south of Roanoke, which is currently known as Hatteras Island, and was also the name of the Native American tribe that inhabited the island.

This has led to speculation that the colonists may have moved to this island or integrated with the Native American tribe, particularly in the absence of any sign of struggle or conflict at the abandoned colony.

However, without any definitive historical or archaeological evidence to support these theories, the true meaning of “CROATOAN” in relation to the fate of the Roanoke colonists remains one of the great unsolved mysteries of history.

3. Who were the eight primary individuals suspected in the Zodiac case?

Over the years, law enforcement and amateur sleuths have investigated numerous individuals as potential suspects, but none have been definitively proven to be the Zodiac Killer.

There were various suspects and persons of interest over time, but it is challenging to provide an exhaustive list, as new information and leads may have emerged after my last update.

Some of the individuals who were primarily suspected at various points in the investigation include:

  1. Arthur Leigh Allen: Perhaps the most infamous suspect, Allen was extensively investigated by law enforcement and journalists. However, no concrete evidence linking him to the Zodiac murders was found during his lifetime.
  2. Richard Gaikowski: A journalist named Paul Avery received a tip naming Gaikowski as the Zodiac Killer. However, the evidence against him was circumstantial, and he was never formally charged.
  3. Lawrence Kane: A former high school teacher, Kane was reportedly obsessed with the Zodiac case. He was investigated but never officially linked to the crimes.
  4. Ross Sullivan: Sullivan was a mentally unstable man with a history of violent behavior. Some have speculated that he might have been the Zodiac Killer due to his resemblance to the police sketch and proximity to one of the murder scenes.
  5. Ted Kaczynski (the Unabomber): Some theories suggested that the Unabomber could be the Zodiac Killer, but there is no substantial evidence supporting this connection.
  6. Earl Van Best Jr.: He was the father of a man named Gary Stewart, who claimed to have evidence linking his father to the Zodiac crimes. However, these claims have been heavily criticized and not widely accepted.
  7. Jack Tarrance: An ex-military man, Tarrance was investigated due to some circumstantial connections, but nothing concrete was found to implicate him.
  8. Various other unnamed suspects: There were numerous other individuals who were briefly considered as suspects, but they were mostly ruled out due to lack of evidence or other factors.

It’s important to remember that suspects and theories in such notorious unsolved cases can change over time as new information surfaces or advances in technology offer fresh avenues of investigation.

As of now, the true identity of the Zodiac Killer remains one of the most significant mysteries in American criminal history.