Answer: Dennis Rader

Dennis Rader, an infamous serial killer known as the “BTK Killer” before his arrest and conviction revealed his true identify, was active in the Wichita, Kansas area between 1974 and 1991. As if the grisly murders he committed didn’t garner him enough fame, he would frequently send letters to police stations and local newspapers describing the murders. Despite the strange (and rather physical) evidence he kept mailing in, police were never able to use the letters to ascertain the identity of the killer.

After a long period with no murders that fit the killer’s profile and no contact via letters, reporters hypothesized that the BTK Killer had died. Shortly after that the letters resumed and the BTK Killer asked the police if they could trace the identity of someone via floppy disk. The police responded that they could not, in fact, do so. The next letter they received from Rader came in an envelope with a 3.5″ floppy disk. Police found a deleted Microsoft Word document on the disk, and the metadata for the document indicated it was created at a local church by a user named Dennis. The police quickly identified Rader and compared his daughter’s DNA (from a Pap smear) to samples taken from previous crime scenes, which provided a familial match.

While it’s possible Rader was skilled at evading police but a novice computer user, many believe, in light of the question about the security of floppy disks that preceded the disk’s arrival, that Rader was effectively turning himself in.