Good catch on the disguise if that works. Hadn't considered it when I was mucking about.
I haven't tested it on this particular scenario but it should work...generally speaking regardless of origin or anything else when you kill NPCs in BG3 you can't use speak with the dead on them because they refuse to talk to their killers but if you disguise self before killing them they'll talk to you because they don't know it was you who killed them.
