Reports of the arrest come from Belgian newspaper De Morgen (via ANN and a Belgian Japanese studies blog) who says that the victim was a French national who was a roommate with one of the suspects in custody. After an altercation between the two the former was killed and the Belgian man and two accomplices tried to dissolve the body with acid, failing, and then just cutting it up and leaving the remains in Saint-Gilles' Dudenpark. Near the bodies were two identically worded notes in poorly written block lettering: "WATASHI WA KIRA DESS." These jackholes could have used penmanship and Japanese lessons.
The kicker is that police say one of the suspects was a manga fan and, obviously, a big fan of Death Note, which has caused a fair amount of reaction from the warrens of society that think anime and manga are child-corrupting guides to devil worship. Now, I don't know about you, but it doesn't sound like the French national was killed because of that particular series. If anything, the notes seem to have been an afterthought or even a red herring to throw the cops off. Whatever the case, it doesn't change the fact that somebody was killed and manga will be forever linked with this heinous act.