The kidnapping of one-year-old Charles Lindbergh Jr. in 1932 was dubbed the "crime of the century," and the overwhelming amount of circumstantial evidence pointed to Bruno Hauptmann as the culprit.

Dave Toschi investigated the Zodiac case for decades, while his eclectic style also inspired Hollywood detectives like Frank Bullitt and "Dirty Harry" Callahan.

On October 28, 2015, Sophia Koetsier vanished while walking to the bathroom at Murchison Falls National Park. Two days later, her belongings were found strewn along a riverbank — but nobody could determine exactly what happened to her.

Although rumors about Polybius and the strange effects the video game had on players have spread for decades, nobody has ever found an arcade machine or any other evidence that the game is real.

Michael Gargiulo brutally murdered at least three women, including one who was dating actor Ashton Kutcher, before he was eventually arrested in 2008.

Although prison officials insisted that Kenneth Trentadue had hanged himself, he had injuries inconsistent with suicide — and his family believes he was beaten to death by guards after being mistaken for an Oklahoma City bombing suspect.

Joshua Maddux's family spent seven years searching for him after the 18-year-old vanished in 2008. His body was stuck in the chimney of an empty house just a quarter-mile away.

After Byron David Smith fatally shot Nicholas Brady and Haile Kifer on Thanksgiving Day 2012, investigators discovered an audio recording of Smith taunting the teenagers as they lay dying on his basement floor.

Between May 1990 and July 1991, Jeffrey Dahmer killed and dismembered 12 men and teenage boys in Apartment 213 of Milwaukee's Oxford Apartments before one of his intended victims escaped and led the police back to the crime scene.

On the third day of his trial for the murder of seven-year-old Anna Bachmeier, Klaus Grabowski was shot in the back six times by Anna's mother, Marianne, in a German courtroom.