Oh. Well i appreciate your help. i take it you haven't found your suspect? If there in fact are demons here, you might never find the murderer. When a person is possessed, their mind is possessed too.. so if the murder was by a demon possessed person, they will not remember it. Your best bet is making a public statement about evidence you've found, and evidence you need. The person might be wondering why there's blood on their clothes, why they have a knife or any kind of weapon. . And might cooperate.