MURDERED: Bill & Peggy Stephenson

In 2011, 74-year-old high school sweethearts Bill and Peggy Stephenson were found murdered inside their Kentucky condo on Memorial Day weekend. Nothing valuable appeared to be missing, but the crime scene was so strange that detectives wondered whether the killer was trying to leave a message. For years, the case pulled investigators in every direction — until one piece of evidence, mailed across the country more than a decade earlier, finally got a hit.