While all of these tragic acts are deplorable, it is clear that despite the millions of people now engaged in MMO games real life violence stemming from them is very rare. In April 2008 a study carried out at Middlesex University found that World of Warcraft had no link with increased aggressive tendencies. In fact, quite the opposite maye be true as many people were calmer after a session. The real factor governing the likelihood of violence is personality type - violent people can be triggered by anything, including games but they have that proclivity to begin with. They don’t become imbued with violent tendencies by gaming.
Most of the cases of real life violence which have been linked to games are clearly motivated by classic human behaviours rather than the act of playing the game itself. The student stabbing his friend after an argument was clearly highly strung to say the least but the incident only has the most tenuous link to gaming. The clan warfare is classic tribalism - humans behave differently in groups and the psychology of mob behaviour is well documented. The kids trying to fund their addiction through murder happened to need the money for online gaming. If they had needed it for drugs we might never even have heard about the story.
The sword theft murder is a much more potentially thorny issue. The rise of virtual crime, particularly in Asia, is well documented. If people are going to put real money values on virtual items and property then theft will have a real world impact. If crimes go unpunished this is an obvious potential cause of real life violence and so we are starting to see virtual crimes resulting in real world punishment.
Any time people invest their time, their money and their emotions in something there is a risk that they will become upset if it goes wrong. For most of us becoming upset might result in an angry rant or a mouse thrown onto the floor. For people with a violent personality type it can have much more serious consequences. There is no justification for real life violence but there are always triggers for these events. Perhaps if these crimes are dealt with in the virtual environment they need never spill over into real life violence. In MMO mad South Korea there is already a branch of the police dedicated to in game crime. In contrast, in the US a Final Fantasy XI player recently tried to report the theft of items worth around $3,800 from his account which had been hacked into and the police refused to investigate. It is a topic which is still being hotly debated.