• Kyodo


The baffled Metropolitan Police Department’s hunt for an elusive cyber-riddler made progress Sunday after a Tokyo man was arrested on suspicion of making anonymous online threats last year by remotely manipulating other people’s computers.

Yusuke Katayama, a 30-year-old resident of Koto Ward, was arrested Sunday morning but denied any wrongdoing, the police said. He has been charged with forcible obstruction of business for allegedly posting a threat online last August stating that mass murder would take place at a comic book event, forcing security to be tightened.

The case, which also involves cyberthreats against a kindergarten, resulted in the wrongful arrests of four people from July to September whose computers were infected by a virus used to send the messages.

Police suspect Katayama used the PCs to send more than 10 threats last year, either by posting them online or via email, and said he was previously convicted in a similar case in 2006.

The police searched Katayama’s home Sunday to look for evidence he sent an email to reporters on Jan. 5 that hinted he was behind the menacing messages. Since last October, a person claiming to be the culprit has sent messages to newspapers and a Tokyo lawyer detailing some 13 cyberthreats.

In the most recent message, recipients were given an “additional puzzle” to solve: locating a memory chip on the collar of a cat on Enoshima Island, a popular tourist spot off Kamakura in Kanagawa Prefecture.

The police found a micro SD card on a cat’s collar the same day. The chip had the source code for the virus used on the four people’s PCs and a message that said: “Because I was embroiled in a criminal case before — despite my innocence — I was forced to make major changes to my life.”

A security camera on Enoshima captured footage of a man resembling Katayama approaching the cat, which already had a collar, the police said, adding they also have footage of a motorbike he apparently used.

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