State v. Rider
Supreme Court of Missouri
1 S.W. 825 (1886)
Rider (defendant), suspecting R.P. Tallent of having an affair with his wife, armed himself with a shotgun and walked to Tallent's house searching for his wife. Tallent approached Rider with an axe intending to strike him; after Rider told him to stop, Rider shot and killed him. At trial, the court instructed the jury that Rider was guilty if it found he had gone to Tallent's home intending to kill him, armed himself, searched for Tallent, and then shot and killed him. Rider was convicted of first-degree murder and appealed.
Whether, to be convicted of murder, a defendant must have both the intent (mens rea) to commit the crime and take some act (actus reus) to carry out or complete the crime, such that abandoning the intent before acting defeats the charge.