I'm more and more convinced that the murderer is Drusilla, and that she's a hag of some kind.
- Her description, behaviour and home are dead-ringers for Auntie Ethel - Via her home she had easy access to all the murder places, including the tower for Selwyn's (he was in the water) - Hags are physically strong as well as powerful magic users, and most of the murders require physical strength and powerful magic - Hags have a cruel sense of humour; hanging up the butcher "like a pig" clearly fits into that - Hags are also collectors and craft potions and items with body parts. She could have used the white drangonborn's skin to freeze Selwyn. - Hags know everyone and everything going on; gossip is their main marketing pipeline. If any of the people involved with the victims ever went to see her (for love potions, advice, or other) that would be her connection to everyone in the city.
We should be focusing on places connected to water, see what happens.
