*SPOILER ALERT!* If you are referring to the Justice Wargrave in "And Then There Were None", his motive was simply to bring justice to the murders where the "murderers" had gotten of Scots-free. Even though some of them didn't actually kill someone, he felt a need to kill all of the people that had killed someone and gotten off free. However, he also was motivated by the morbid and sick thought of wanting to commit the perfect murder: one where no one could ever solve it.
Mr. Justice Wargrave's motive in Agatha Christie's novel "And Then There Were None" was to punish those he believed had escaped justice for their crimes by orchestrating their deaths on Soldier Island. He wanted to uphold justice in his own twisted way and believed that his actions would serve as a form of retribution for their crimes.
Mr. Justice Wargrave is a retired judge.
Indian Island
At the outset of the novel "And Then There Were None" by Agatha Christie, Mr. Justice Wargrave is traveling to Indian Island as a guest invited by the mysterious host, U.N. Owen.
Wargrave's meticulous planning and attention to detail suggest a level of premeditation not typically associated with an innocent person. He has a deep knowledge of criminal psychology and uses it to manipulate the other guests. Wargrave admits to orchestrating the murders in a letter found at the end of the novel. His fascination with justice and his own sense of superiority point to a potential motive for committing the crimes.
In the book And Then There Were None, Mr.Justice Waregrave was the murderer. Justice Wargrave had asked Dr Armstrong to fake his death so he can rattle the people. All of the deaths after Mr Wargrave's were a coincidence. Justice Wargrave had put the potassium cyanide in Anthony Marston's drink and put sleeping pills in Mrs Rogers' drink. He had also hit Mr Rogers and General MacArthur in the head with a blade and inject a poison into Emily Brent's neck.
Lawrence Wargrave faked his death with the help of Dr. Armstrong. Dr. Armstrong injected Justice Wargrave with a medicine that slowed down his heartbeat, making it appear as though he had died from a gunshot wound.
In "And Then There Were None," Justice Wargrave's confession in the bottle reveals his true identity as the murderer orchestrating the deaths on the island. He admits to his crimes and explains his motivations for wanting to deliver his own form of justice.
Justice Wargrave becomes involved in crime by manipulating the circumstances to create an opportunity for murder. He uses his position of authority and respect to gain the trust of the other characters, only to ultimately betray them by orchestrating a series of killings on the island. His cunning and calculating nature allow him to meticulously plan and execute the murders without raising suspicion.
This is my favorite book by Agatha Christie! The order of deaths was Tony Marston, Mrs. Rogers, General MacArthur, Mr. Rogers, Emily Brent, Justice Wargrave, Dr. Armstrong, Mr. Blore, Philip Lombard and then Vera Claythorne. Tho actually it was Justice Wargrave who died last since he was behind it all and killed himself after he wrote the letter confessing, or rather proudly proclaiming that it wad him.
Mr. Lawrence Wargrave did all of this because he is obviously U.N. Owen, and he knew everything all along. He laid low and let everybody think it was someone else. He did these things because they all commited, including Wargrave, a crime that couldn't be dealt with in court. And he was obsessed with the laws and safty of his country.
Vera Claythorne is a former governess who feels guilt over the death of her charge, while Justice Wargrave is a retired judge who orchestrates the murders on the island to deliver his own form of justice. Vera is more emotionally vulnerable and conflicted, while Wargrave is calculated and believes in the righteousness of his actions.
The killer in the book and then there were none is Justice Lawence Wargrave. He secretly killed his victems one by one. He faked his death at one point with the help of doctor Armstrong. The thing is that dr Armstrong had no idea that wargrave was the killer. He thought that by helping fake the death it would give wargrave a chance to see who was doing all of the killing. In the end he writes his confession in a bottle and kills himself.