Top Ten Cases, No Closure: The World’s Most Enduring Unsolved Crimes

Every case below was investigated by real police departments, often for years, with resources that were substantial for their time. None of them lack for suspects. What they lack is proof that would hold up in court, and in several instances a body of evidence that survived intact long enough to be tested with today’s tools.

1. Jack the Ripper — London, 1888

The oldest case on this list arguably invented the modern idea of a serial killer as a media phenomenon. Between late August and early November 1888, five women, Mary Ann Nichols, Annie Chapman, Elizabeth Stride, Catherine Eddowes, and Mary Jane Kelly, were murdered and mutilated in and around Whitechapel in East London. All were killed at night in public or semi-public spaces, and the mutilations grew more severe as the killings continued.

What made the case unusual for its era was correspondence. Letters signed “Jack the Ripper,” including the “Dear Boss” letter and a note sent with part of a human kidney known as “From Hell,” went to police and the press, though historians still debate how many were genuine versus hoaxes by journalists chasing sales.

Scotland Yard investigated more than a hundred suspects at the time, and over a century of research has added many more, from painter Walter Sickert to barrister Montague John Druitt to Polish immigrant Aaron Kosminski, who a controversial 2014 DNA analysis of a bloodstained shawl claimed to implicate. That shawl’s chain of custody has never been independently verified to modern forensic standards, and no claim has satisfied the wider historical or scientific community. The Metropolitan Police file remains formally closed as unsolved.

Sources: The National Archives (Metropolitan Police files, MEPO 3/140–3/141); Metropolitan Police; Wikipedia overview and citation index.

2. The Zodiac Killer — Northern California, 1968–1969

The Zodiac’s first confirmed attack was on Lake Herman Road near Benicia on December 20, 1968, killing teenagers David Faraday and Betty Lou Jensen. Over the following ten months he shot or stabbed victims in Vallejo and Napa County before killing San Francisco cab driver Paul Stine on October 11, 1969, the only murder within city limits.

What separates this case from most is the killer’s decision to communicate. He sent cryptic ciphers to the San Francisco Chronicle and other outlets, claiming a much higher body count than investigators ever confirmed. One cipher, known as Z340, went unsolved for 51 years until independent codebreakers David Oranchak, Sam Blake, and Jarl Van Eycke cracked it in December 2020, though the decoded text revealed no identifying details.

The FBI’s public position hasn’t moved in over half a century: as recently as 2021 the bureau publicly rebutted a claimed identification of the killer, stating the case remains open. Dozens of named suspects have circulated, including Arthur Leigh Allen, who died in 1992 without being charged, and more recently Gary Francis Poste, named by an amateur group called the Case Breakers in 2021. Neither the FBI nor local agencies have confirmed either identification, and DNA recovered from Zodiac letters hasn’t conclusively matched any named suspect. As of late 2025, the case remains officially open in every jurisdiction that handled it.

Sources: FBI public statements; San Francisco Chronicle archives; Vallejo Police Department case files; Wikipedia overview and citation index.

3. The Black Dahlia — Los Angeles, 1947

On the morning of January 15, 1947, a mother walking with her young daughter discovered the body of 22-year-old Elizabeth Short in a vacant lot in Leimert Park. The body had been severed at the waist and drained of blood, with no blood found at the scene, meaning she had been killed and likely mutilated elsewhere before being posed and left in public.

Short, an aspiring actress from Massachusetts, was nicknamed “the Black Dahlia” by the press. The case became a sensation, and the LAPD fielded so many false confessions that investigators had to develop corroborating details known only to police in order to filter them out.

More than 150 suspects have been formally investigated over the decades, including a theory, argued in a 2003 book by his own son, a retired LAPD detective, implicating local physician Dr. George Hodel. The LAPD has never reopened the case on that basis, and no forensic evidence has ever definitively linked any suspect to the crime.

Sources: Los Angeles Police Department historical case archives; Los Angeles Times archival coverage, January–February 1947; Wikipedia overview and citation index.

4. D.B. Cooper — Pacific Northwest, 1971

On the day before Thanksgiving 1971, a man calling himself Dan Cooper boarded Northwest Orient Flight 305 in Portland, told a flight attendant he had a bomb, and demanded $200,000 in cash and four parachutes. After the plane landed in Seattle and his demands were met, he released the 36 passengers, ordered the crew to fly toward Mexico at low altitude, and jumped from the aircraft’s rear stairway somewhere over the forests of southwest Washington. He was never seen again.

The FBI ran an active investigation, code-named NORJAK, for 45 years before redirecting resources away from it in July 2016, though it was never declared solved. The only physical break came in 1980, when an eight-year-old boy named Brian Ingram found a decaying bundle of the ransom bills partially buried on a bank of the Columbia River.

Whether Cooper survived the jump remains genuinely disputed; the terrain was remote, cold, and heavily forested, and no parachute, remains, or further ransom money has ever surfaced. It’s the only unsolved hijacking of a commercial aircraft in American history.

Sources: FBI NORJAK case summary; FBI historical case page; Wikipedia overview and citation index.

5. JonBenét Ramsey — Boulder, 1996

On the morning of December 26, 1996, John and Patsy Ramsey reported their six-year-old daughter, JonBenét, a child pageant competitor, missing from their Boulder home. A ransom note demanding $118,000, oddly matching a bonus John Ramsey had recently received, was found on a staircase. Hours later, John Ramsey found his daughter’s body in a small room in the basement. She had been strangled with a garrote fashioned from a paintbrush handle and cord, and had also suffered a skull fracture.

The investigation was compromised almost immediately when friends and family were allowed to move through the house before it was properly secured. A grand jury that heard evidence in 1999 declined to indict, and in 2008 the Boulder County District Attorney formally cleared the family based on DNA testing that matched an unidentified male, not a family member.

That unidentified DNA profile remains the central hope for resolution. Boulder Police have confirmed in recent annual updates that they continue submitting evidence for advanced testing and forensic genetic genealogy, the technique that identified the Golden State Killer, though no confirmed match has been announced publicly.

Sources: Boulder Police Department annual case updates; Boulder County District Attorney’s Office, 2008 clearance letter; Wikipedia overview and citation index.

6. The Isabella Stewart Gardner Museum Heist — Boston, 1990

In the early hours of March 18, 1990, two men dressed as Boston police officers talked their way into the Isabella Stewart Gardner Museum, claiming to be responding to a disturbance call. Once inside, they handcuffed both guards on duty and bound them in the basement, then spent roughly 81 minutes moving through the galleries. They left with 13 works, including Vermeer’s “The Concert,” one of only 36 known Vermeer paintings in the world, three Rembrandts including his only known seascape, and pieces by Manet and Degas.

Per the terms of Isabella Stewart Gardner’s own will, the museum can’t rearrange its collection, so the empty frames still hang on the gallery walls today. The combined works are valued at more than $500 million, making this the most valuable unsolved art theft in history, and the museum’s reward for information now stands at $10 million.

In 2013, FBI investigators announced they believed they had identified the thieves, tied to a criminal organization with reach across the mid-Atlantic and New England, but said those responsible were already dead and the statute of limitations on the theft had expired. No arrests were ever made, and not a single piece has surfaced on any market in over three decades.

Sources: FBI Boston Field Office statements, 2013 and 2015; Isabella Stewart Gardner Museum public reward notices; Wikipedia overview and citation index.

7. The Hinterkaifeck Murders — Bavaria, 1922

Hinterkaifeck was a small, isolated farm in Bavaria belonging to the Gruber family. In late March 1922, farmer Andreas Gruber, his wife Cäzilia, their adult daughter Viktoria, her two young children, and a newly hired maid were all found bludgeoned to death, apparently with a mattock. Investigators later determined the killer had continued living on the farm for several days afterward, feeding the livestock and apparently cooking meals, before disappearing.

In the days before the murders, Andreas Gruber told neighbors he had heard footsteps in the attic and found strange items around the property, including a newspaper that didn’t belong to the family and a missing set of house keys, suggesting someone had been surveilling the farm beforehand.

Bavarian police investigated over a hundred suspects, focusing partly on rumors surrounding Viktoria’s younger child, a motive theory investigators found plausible but were never able to substantiate. The Bavarian State Criminal Police reopened the case in 2007 using modern forensic methods on preserved skulls, but closed it again in 2009 without resolution.

Sources: Bavarian State Criminal Police (Bayerisches Landeskriminalamt) 2007–2009 review; contemporary Bavarian press archives; Wikipedia overview and citation index.

8. The Chicago Tylenol Murders — 1982

Over the last week of September 1982, seven people in the Chicago area died after taking Extra-Strength Tylenol capsules laced with potassium cyanide. The first victim was 12-year-old Mary Kellerman. Investigators determined the tampering happened after the bottles left the factory, meaning someone bought bottles off store shelves, inserted lethal doses of cyanide, and returned them to shelves in at least six different stores, with no known connection to any victim.

The case triggered a nationwide recall of 31 million bottles of Tylenol and led directly to the federal Anti-Tampering Act of 1983, along with the tamper-evident packaging and safety seals now standard on nearly every over-the-counter medication sold in the U.S.

A man named James Lewis was convicted of extortion after sending a letter to Johnson & Johnson demanding $1 million to “stop the killing,” but investigators were never able to tie him to the actual poisonings, and he denied involvement until his death in 2023. No one has ever been charged with the murders themselves.

Sources: FBI Chicago Field Office case archives; U.S. Food and Drug Administration historical records on the 1982 recall; Wikipedia overview and citation index.

9. The Boy in the Box — Philadelphia, 1957

On February 25, 1957, a college student checking muskrat traps near a wooded area of Philadelphia discovered a cardboard box containing the body of a young boy, roughly four to six years old, malnourished and showing signs of having been beaten. For 65 years, despite one of the largest identification efforts in American law enforcement history, including over 400,000 circulated flyers, nobody could determine who he was, and he became known as “America’s Unknown Child.”

The case finally broke, in part, in December 2022, when investigators using forensic genetic genealogy identified the child as Joseph Augustus Zarelli, born in Philadelphia in January 1953. That resolved one half of the mystery but not the other: no suspect in his death has ever been named, and Philadelphia’s cold case unit continues to treat his killing as an open homicide investigation.

Sources: Philadelphia Police Department cold case unit, December 2022 identification announcement; Vidocq Society case files; Wikipedia overview and citation index.

10. The Axeman of New Orleans — 1918–1919

Beginning in 1918, a series of brutal attacks struck New Orleans, largely targeting Italian-American grocers and their families at night. The attacker typically broke in through a rear door, then struck victims with their own axe, which he left behind rather than taking with him. Several attacks were fatal, and the seemingly random selection of victims spread genuine panic through the city’s Italian immigrant community.

In March 1919, a letter published in New Orleans newspapers, purportedly from the killer, claimed to be a demon from hell and declared he would kill again on a specific night unless every household in the city was playing jazz music when he passed by. New Orleans, by every account, complied, with dance halls packed and jazz bands hired for private homes across the city that night. No attack occurred.

The attacks stopped abruptly in October 1919 with no arrest and no confirmed motive. Theories range from a scorned suitor with grudges against Italian grocers, to organized crime intimidation connected to the Black Hand, to an unrelated string of copycat crimes attributed to one mythologized figure by sensationalist press coverage. Records from the period are incomplete, and no modern forensic reexamination has ever been possible.

Sources: New Orleans Police Department historical records (period incomplete); contemporary New Orleans Times-Picayune coverage, 1918–1919; Wikipedia overview and citation index.