In a sense you can charge them with mischief causing death. Mischief can be defined as the prevention of using information or data. The virtual goods are technically information since they're just bits of data on a server. Since they could have caused death and the intent is implied by a knife being used, causing death would still apply even though a death didn't take place. This is Canadian law, so I'm not sure how it works in the Netherlands. You can get life imprisonment for it here.