What is the name of the narrator and murderer in 'The Murder of Roger Ackroyd'?

Dr. James Sheppard is the narrator and murderer in The Murder of Roger Ackroyd. He presents the story as a local doctor assisting Hercule Poirot, while carefully concealing his own role in Roger Ackroyd's death.

Sheppard lives with his unmarried sister Caroline in the fictional village of King's Abbot. He becomes involved after Ackroyd, a wealthy businessman and widower, is found murdered. Sheppard's first-person account appears reliable because he records events in a calm, clinical style and seems to function as Poirot's assistant.

The famous twist reveals that Sheppard himself committed the murder. Christie makes him an unreliable narrator without requiring him to state an outright falsehood: selective phrasing and omissions hide what he has done. In the final pages, he explains that he is writing the account before taking his own life. Captain Hastings is not the narrator of this novel; he is absent because he has married and settled in Argentina. The book was published in 1926 and is celebrated for transforming the detective-story narrator into the culprit.