Thanks to the comment by the supplier about Fel whispering to him, I'm wondering if each murder was committed by a different person compelled by Fel this way.
I think so, too. I would focus on getting more information about Fel.
This is a very wild guess, but could the retching man maybe - involuntarily - have killed the elf, magically compelled by Fel?
I am glad we have the whole weekend to decide where to investigate next.
