In 2005, Dennis Rader pulled a very juvenile and very idiotic stunt which ultimately lead to his arrest 30 years after his first murder.

Rader began leaving clues in cereal boxes around Wichita, Kansas. He wrote “bomb” “BTK” and “box gram” on the outside. On the inside of one of the boxes, he stuffed a bound barbie doll tied up the way his victim, Josephine Otero was found. In another box, FBI agents found jewelry that belonged to one of his victims.

An employee at a local Home Depot told police that his girlfriend found a cereal box in the back of his truck, but she had just thrown it away. Police dug through the dumpster and found BTK’s last clue. Inside were documents that described the killer’s crimes. There was also a document with the question, “Can I communicate with floppy and not be traced back to computer? Be honest.” The police, of course, lied when answering the inquiry in a classified ad. When they received the floppy disc, they were able to track the serial killer down, and arrest him for the murders of ten people in Kansas. 

Sources: (x)(x)(x