TIL Dennis Rader, the "BTK" killer, contacted police and asked "Can I communicate with Floppy and not be traced to computer? Be honest." Police told him he could, and Rader sent them a disk. Forensic analysts then identified him through metadata from a deleted MS Word file the disk contained.

http://www.policechiefmagazine.org/magazine/index.cfm?fuseaction=display_arch&article_id=1065&issue_id=122006