Sydney told Newsweek the condition of the note and the place it was found in hinted at something heartbreaking involving the ...

William Abel, a mail censor at Iowa's State Prison, Fort Madison, using a hot iron to bring out a secret message written in lemon juice on a letter.Three Lions/Getty Images Humans have had a long ...

Humans have had a long history with sending secret messages. The practice dates back to ancient Greeks tattooing a servant's head to a modern-day employee stealing corporate secrets. Invisible ink is ...