Famous Unsolved Crimes

James R. Hoffa, former President of the Teamsters Union, was last seen in late July 1975 outside of a Detroit restaurant. He disappeared without a trace, giving rise to several theories as to what happened to him and where his body was hidden. In September 2012, authorities dug up the driveway of a Roseville, Mich., home in hopes of finding Hoffa's body. Police had received a tip from a man who said he'd seen a body being buried there approximately 35 years ago and thought it may have been Hoffa. The search revealed no human remains.

The murder of JonBen

JonBen

The Disappearance of Etan Patz

Etan Patz flyer — AP Photo/Courtesy NYPD/Getty Images

Etan Patz, a six-year-old New York City boy, vanished while walking to the bus stop in his SoHo neighborhood on May 25, 1979. The investigation into the case spanned decades and continents. In 2001, a judge declared the boy legally dead. Jose Antonio Ramos, a convicted child sexual abuser and friend of Patz's one-time babysitter, was declared responsible for Patz's death in a New York civil case, but in May 2012, a 51-year-old man named Pedro Hernandez confessed to choking Patz to death on the day he disappeared. Hernandez, who worked at a convenience store near Patz's home, has a history of mental illness. He was arrested but police have not cited any evidence against him other than his confession.

The case of the 'Boston Strangler'

Between June 14, 1962 and January 4, 1964, 12 women between the ages of 19 and 85 were found murdered in the Boston area, most of them sexually assaulted and strangled. The crimes confounded the police until 1965 when Albert DeSalvo, an inmate at a mental institution who had been convicted of several sexual assaults, confessed. According to the New York Times, DeSalvo claimed to have committed over 300 sexual assaults. But police were doubtful, and DeSalvo was never charged with any of the crimes. He was murdered in prison in 1973. Since then several theories of the crimes have emerged, including that the stranglings were committed by multiple perpetrators.

The deaths of Nicole Brown Simpson and Ronald Goldman

On June 14, 1994, Nicole Brown Simpson and her friend Ronald Goldman were slashed to death outside her condominium in Los Angeles. Simpson's ex-husband, football star and actor O.J. Simpson was charged with their deaths but acquitted after a much-watched criminal trial. Simpson has maintained his innocence but was found to have caused their deaths in a 1997 civil trial. In 2006, a copy of a manuscript written by Simpson entitled "If I Did It" and set to be published Reagan books, a former imprint of HarperCollins, leaked online. The book, in which Simpson hypothesized how he would have killed Simpson and Goldman, set off a backlash that culminated in the company cancelling publication of the book and a planned TV special, and firing publisher Judith Reagan.

Airplane hijacker "D.B. Cooper"

This is an artist's sketch of the skyjacker known as 'Dan Cooper' and 'D.B. Cooper', from the recollections of passengers and crew of a Northwest Orient Airlines jet he hijacked between Portland and Seattle, Nov. 24, 1971, Thanksgiving eve. 'Cooper' later — AP Photo/FBI

This is an artist's sketch of the skyjacker known as 'Dan Cooper' and 'D.B. Cooper', created from the recollections of passengers and crew of a Northwest Orient Airlines jet he hijacked between Portland and Seattle on Nov. 24, 1971, Thanksgiving eve. 'Cooper' later parachuted from the plane with $200,000 in ransom money. Dead or alive, he has not been found.

The death of Tupac Shakur

Rap artist and actor Tupac Shakur, 25, was shot four times in Las Vegas, Nevada on September 7, 1996. He died six days later at Southern Nevada University Medical Center. Shakur was leaving the MGM Grand casino after attending the Mike Tyson-Bruce Seldon boxing match when a Cadillac pulled up to Shakur's sedan and someone inside opened fire. Marion "Suge" Knight, the co-founder of Death Row Records, was in the car with Shakur and survived the attack. The case is still unsolved. In 2002, Chuck Phillips, a Pulitzer Prize winning reporter who has spent much of the last 10 years investigating the murder of Tupac, wrote an article for the Los Angeles Times in which he states that evidence he collected indicates that Christopher Wallance (aka Notorious B.I.G., or Biggie Smalls), Tupac's nemesis, supplied the gun used in the shooting and offered to pay a California branch of the Crips gang $1 million to commit the murder.

The death of Natalee Holloway

Alabama high school senior Natalee Holloway disappeared while on a school trip to Aruba in May 2005. Holloway was last seen dancing at Carlos

The death of Notorious B.I.G.

Christopher George Latore Wallace, a rap artist known as The Notorious B.I.G., or Biggie Smalls, was killed in a drive-by shooting in Los Angeles on March 9, 1997 - six months after the death of Tupac Shakur. The crime remains unsolved, but many speculate that Wallace’s death may have been some kind of retribution for Shakur’s, possibly involving members of the Los Angeles Police Department with ties to Marion “Suge” Knight, who was in the car with Shakur when he was shot. In 2011, the FBI released a 359-page file on the investigation, which indicated that Wallace was shot with what the New York Daily News termed “very rare” German ammunition, rounds of which were found int he home of an LAPD officer who worked off-duty for Knight.

The Black Dahlia

The Last Take — Producers Library Service

Elizabeth Short, a 22-year-old waitress who had come to California from Medford, Mass., was found dead, her mutilated body sliced in half, in a Los Angeles vacant lot on Jan. 15, 1947. At the time, the press nicknamed Short "The Black Dahlia." In the years since Short's murder, all physical evidence of the case has disappeared from LAPD's files. L.A.'s most famous unsolved murder mystery may never be solved.