Who was the killer in They came to Baghdad?

In Agatha Christie's novel "They Came to Baghdad," the killer is revealed to be the character known as Mr. Miller, who is involved in espionage and murder. The story centers around a young woman named Victoria Jones, who unwittingly becomes entangled in a complex plot involving international intrigue. The novel combines elements of mystery and suspense, typical of Christie's work, leading to the dramatic revelation of Miller's true identity and motives.