User blog comment:Waters Knight/Nora's Dream?/@comment-3146930-20131123071341/@comment-17711744-20131124224730

Maybe it depends on the method in which you kill them? Notice that the Ursa Nora killed in the beginning of episode eight, and the one Blake killed the episode before that, didn't dissolve. Like, maybe, although we don't know much about it yet, being killed by aura causes them to dissolve? This could make sense, given that Grimm lack both a soul and aura, with them being "pure evil". Like how the Wicked Witch of the West (fire witch) dissolved when Dorothy threw a bucket of water at her?