It might sound like the plot to a low-rent thriller but, in this case, fact really is stranger than fiction. For months, an unknown cyber-criminal has taunted Japanese police with online threats to blow up planes and massacre civilians; now a stray cat has provided the latest clue to the identity of the country’s most audacious hacker.

nown only by the online handle “Enkaku”, the hacker has plagued Japanese authorities for months with a series of mocking clues and riddles teasing at their identity. Having first come to the attention of the public six months ago by breaking into the Yokohama city website to post threatening messages detailing a plan to kill students at a local school, the unknown individual has since become the country’s most wanted cyber-criminal.

The chief weapon in the hacker’s arsenal is a home-grown virus known as iesys.exe, which has allowed them to remotely access computers throughout Japan in order to issue threats of mass violence. While none of these threats have materialised, they have seen police forces deployed to a number of venues. in a first for online crime, the Japanese police are offering a £21,000 reward for information pertaining to the perpetrator’s identity

On January 1st, a number of major Japanese news sources received the latest in a series of riddles distributed by the hacker in the form of an email claiming they were ‘an invitation to a new game’, and offering journalists the ‘chance for a big scoop’. Having solved a series of riddles, authorities were led to the small island of Enoshima, just outside of Tokyo, where a stray cat was found to have a digital flash drive attached to its collar. Police are still analysing the contents of the drive, but it is understood to contain information regarding the workings of iesys.exe, which would be known only to the virus’ author.