Some murder cases are thought to be the work of serial killers. Here are some famous unsolved serial murders in the United States.

Through handwriting analysis, the FBI concluded that all the Anthrax letters were written by the same person. The FBI believes Bruce Ivins was the culprit.

The Amber Room was a coveted treasure from the 18th century, but its fate has been a mystery since WWII. This is the history of the priceless chamber.

Raoul Wallenberg bravely went to Hungary to defy the Nazis and their allies to save Jews. Unfortunately disappeared some months before the war ended.

The Hum is a localized, persistent low-frequency that drives people mad. There are a number of theories as to the origins of this strange phenomenon.

Experts continue studying the mysterious Voynich Manuscript to try to decipher apparent coded language from the early 15th century.

Skeptics claim the stigmata of Padre Pio is self-generated.  But he continues to be one of the most popular saints of Catholicism.

The young Princes in the Tower disappeared after the older prince was about to become King of England. Did King Richard III murder them?