@ gimmepie, yeah, you can do that! No, they don't know what the culprit looks like. The sprites were just for showing what they do look like whenever they are found.
Hm, for those who want, we could make this quest a non-joint posted collaborative one (meaning we just take turns posting in the IC, interacting as in any regular RP) and involve Corvin as a suspect in some way. Not sure how, but maybe you have some good ideas?
Those who want can still do the quest on their own. Things could have gotten stolen several times, in case the characters meet later and discuss what they've been doing in Pewter.