As for the one corpse, there are many possibilities, and I don't even want to bother thinking about them.
For example, all three of them could have wanted to kill Kayla at once... Isn't that a possible version? :) Or at least two of them, and the baker killed her. And the third killer was simply asleep.
I need to think about who the old woman was playing snowball fights with and who the expert was examining.
Added 2 minutes later
Everything revolves around Kayla and Areg :)