One of Illinois' most notorious unsolved killings took place 50 years ago Sunday.
Valerie Percy, 21, was found beaten and stabbed to death in her family's Kenilworth mansion on September 18, 1966.
She was the daughter of businessman and Republican politician Charles Percy, who would go on to be elected U.S. Senator.
No one has ever been charged but investigators have talked to thousands of people and tracked leads across the country.
In his book, "Sympathy Vote," author Glenn Wall raised the possibility that a disturbed man who lived within walking distance of the home might have been responsible.