I'm not sure what the question is asking, or if you are even asking it correctly. I do know that Justice Wargrave was responsible for his own "death" (He faked it.) I also know that Wargrave decidedly killed everyone on the island depicted in the story. The answer would be Justice Wargrave, if you were asking who killed Mr. Blore and Doctor Armstrong. However, I'm not sure what you mean by who was involved in the murder of Justice Wargrave? If it helps, he seemingly faked his death so maybe that could answer your question?
Please let me know if you need more clarification.
