Once the stuff of ropey science fiction movies, the crime of digital murder may be about to go on the books, following the arrest of a middle-aged piano teacher from southern Japan, who snapped and murdered her virtual husband.

According to the Japanese media, the 43-year-old woman hacked into the computer of the man she married in an online game and erased his carefully constructed digital character after their relationship curdled. The messy divorce has sparked a debate among million of online gamers about whether virtual offences should stay in cyberspace, or be punished in the real world.

Police arrested her this week following a complaint by the man, a 33-year-old office worker who lived on the other side of the country in the northern city of Sapporo, 1000 km away. The two have apparently never met offline and the woman, reportedly a real-life divorcee, is not suspected of a flesh-and-blood crime, say the police.

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She faces charges of using her digital partner's password and ID, which she acquired when they were a happily married virtual couple, and using it to illegally access his computer. The charge carries a maximum sentence of five years in prison or a fine of about 3,200 pounds.

"It sounds like a strange case but obviously it is illegal to hack into someone else's computer," said a spokesman for the Sapporo Police, who discussed the case on condition of anonymity. "That is why she has been arrested." The spokesman said he was "surprised" by the attention the case was getting from around the world. "For us it is simply a computer crime."

According to investigators, the woman flew into a rage when the relationship was abruptly terminated. "I was suddenly divorced, without a word of warning. That made me so angry," she was quoted as saying.

The two met while accessing a hugely popular role-playing game called MapleStory, which encourages anonymous users to create online characters that navigate alternative worlds, fight monsters and engage in virtual relationships. Long-term commitments, marriage, and digital sex are not uncommon among players, who are sometimes not even living in the same country. Originally from South Korea, Maple Story now reportedly boasts about 50 million subscribers worldwide, including 9 million in Japan.

Japan is a world leader in online role-playing games, which constantly throw up new innovations that have the uninitiated scratching their heads. A new Japanese service released this year called Virtual Wife allows presumably lonely men to choose from four different partners who nag until them until they lose weight.

The latest case comes amid growing controversy about online crimes. A Dutch court sentenced two teenagers to a total of 360 hours community service this month for virtually beating up a classmate and stealing his digital goods. "These virtual goods are goods (under Dutch law), so this is theft," said the court, which was criticised for going too far.

Online gamers are already debating the implications of the Japanese woman's arrest, with many bloggers supporting the 'murdered' husband. "It takes a lot of time and effort to build up a virtual character. This could mean other wronged parties may seek real-world justice for people who harm them virtually," wrote one blogger approving. "I hope she goes to prison."