Passage: In the confession, Justice Wargrave writes that he has long wished to set an unsolvable puzzle of murder. His victims would be of his choosing, as they were not found guilty in a trial. He explains how he tricked Dr Armstrong into helping him fake his own death under the pretext that it would help the group identify the killer. He also explains that he replaced the chair in Vera's room. Finally, he reveals how he used the gun and some elastic to ensure his own death matched the account in the guests' diaries. Although he wished to create an unsolvable mystery, he acknowledges in the missive a "pitiful human need" for recognition, hence the confession.

Question: Based on this passage, who was the murderer in and then there were none movie?
Steam of consciousness below:
To answer the above question, the relevant sentence is: In the confession, Justice Wargrave writes that he has long wished to set an unsolvable puzzle of murder.
So, the answer is Justice Wargrave.