Top 10 unsolved crimes in the USA

1. The Zodiac Killer

The Zodiac Killer was a serial killer who operated in northern California in the late 1960s and early 1970s. The killer's identity remains unknown. Four men and three women between the ages of 16 and 29 were targeted. The killer originated the name "Zodiac" in a series of taunting letters sent to the local Bay Area press. These letters included four cryptograms. Of the four cryptograms sent, only one has been definitively solved.

2. Tupac and Biggie Smalls

On the 1996 night Tupac Shakur was killed in Las Vegas, Suge Knight was nabbed for violating his probation (for stomping a guy); he spent five years in prison. During this time, Knight's former high school classmate and head of security, Reggie Wright Jr., took over the bulk of Knight's duties at Death Row Records, the once–obscenely popular rap imprint, which was about to go downhill.

 3. D.B Cooper

After hijacking a plane Northwest company that made traveling between Portland and Seattle, Cooper got that authorities will provide $ 200,000 in cash and two parachutes in exchange for free the passengers of the flight. He then ordered the pilot to go to Mexico City and in a  desert area between Seattle and Reno, jumped into the gap. Almost forty years later, still has not solved the mystery of the fate of criminal famous after his daredevil jump.

4. Tylenol poisonings

  The Chicago Tylenol murders were a series of poisoning deaths resulting from drug tampering in the Chicago metropolitan area in 1982. The victims had all taken Tylenol-branded acetaminophen capsules that had been laced with potassium cyanide. James William Lewis was convicted of extortion for sending a letter taking credit for the deaths and demanding $1 million to stop them, and he was also the primary suspect in the killings despite living in New York City at the time. The incidents led to reforms in the packaging of over-the-counter substances and to federal anti-tampering laws.

5. The Black Dahlia

"The Black Dahlia" was a nickname given to Elizabeth Short (July 29, 1924 – c. January 15, 1947), an American woman who was the victim of a gruesome and much-publicized murder. Short was found mutilated; her body sliced in half at the waist, on January 15, 1947, in Leimert Park, Los Angeles, California. Short's unsolved murder has been the source of widespread speculation, leading to many suspects, along with several books and film adaptations of the story. Short's murder is one of the oldest unsolved murder cases in Los Angeles history.

6. Jonbenét Ramsey

JonBenét Patricia Ramsey (August 6, 1990 – December 25, 1996) was an American girl who was murdered in her home in Boulder, Colorado in 1996. The six-year-old's body was found about eight hours after she was reported missing, in the basement of the family home, during a police search of the home. She had been struck on the head and strangled. The case remains unsolved, even after several grand jury hearings, and continues to generate public and media interest.

Colorado law enforcement agencies initially suspected Ramsey's parents and her older brother Burke. However, the family was partially exonerated in 2003 when DNA taken from the victim's clothes suggested they were not involved. Her parents were not completely cleared until July 2008. In February 2009, the Boulder Police Department took the case back from the district attorney to reopen the investigation. 

7. Disembodied feet

Since August 2007, five human feet have washed ashore near Vancouver, British Columbia. No bodies, no heads, no clothes, just feet (4 left, 1 right), nearly all still clad in sneakers. Canadian authorities have yet to determine how the feet ended up there or why, though DNA tests matched one of the severed feet to a man who'd been missing for several months. A number of theories have been tossed around, including the possibility of foul play (though coroners familiar with the case say ocean currents and decomposition could have naturally separated the feet from their owners). Others speculate the remains might belong to four unrecovered victims of a 2005 plane crash off Quadra Island.

 8. Gardner Museum

In the early morning hours of March 18, 1990—as the city was preoccupied with Saint Patrick's Day celebrations—a pair of thieves disguised as Boston police officers gained entry to the Isabella Stewart Gardner Museum and stole thirteen works of art. The thieves had to make two trips to their car with the artwork. The theft lasted 81 minutes. The guards remained tied and handcuffed until the police arrived at 8:15 a.m. later that morning.

 9. Jimmy Hoffa

James Riddle "Jimmy" Hoffa (born February 14, 1913 – disappeared July 30, 1975) was an American labor union leader who vanished in late July 1975, aged 62. He is widely believed to have been murdered. Hoffa became involved with organized crime from the early years of his Teamsters work, and this connection continued until his disappearance in 1975. He was convicted of jury tampering, attempted bribery and fraud in 1964. He was imprisoned in 1967 and sentenced to 13 years, after exhausting the appeal process. In mid-1971 he resigned as president of the union, an action that was part of a pardon agreement with President Richard Nixon, to facilitate his release later that year. Nixon blocked Hoffa from union activities until 1980 (which would have been the end of his prison term, had he served the full sentence). Hoffa attempted to overturn this order and to regain support.

Hoffa was last seen in late July 1975, outside the Machus Red Fox, a suburban Detroit restaurant. His disappearance gave rise to many theories as to what happened to him.

 10. Whitechapel

The Whitechapel murders were committed in or near the impoverished Whitechapel district in the East End of London between 3 April 1888 and 13 February 1891. At various points some or all of these eleven unsolved murders of women have been ascribed to the notorious unidentified serial killer known as Jack the Ripper. The Metropolitan Police, City of London Police, and private organizations such as the Whitechapel Vigilance Committee were involved in the search for the killer or killers. Despite extensive inquiries and several arrests, the culprit or culprits evaded identification and capture. The murders drew attention to the poor living conditions in the East End slums, which were subsequently improved. The enduring mystery of who committed the crimes has captured public imagination to the present day.