I think either way, we're not going to get any further without speaking directly to Kindjal the younger. She's the one we've identified as the killer, and if we want to find out why she's been killing nobles, she's the one to tell us (plus we have direct leverage over her).

If we don't care about the why, we can just turn over our evidence to the Comissariat and let them deal with it. Obviously we'll need to concoct a story as to how we we're able to determine the identity of the killer so quickly, and there's the slight problem that her identity isn't clearly shown in any of the camera footage, but we can probably work something out.

For the OOC record, Hannabel cares more about the why than actually seeing Kindjal junior punished for her crimes. Lots of dead Scintillan nobles aren't a huge concern for her.