One Piece Chapter 4, page 10: Chapter 4: The Great Captain Morgan

Morgan demands obedience, but Lieutenant Rokkaku firmly refuses to murder a little girl. Labeling it mutiny, Morgan instantly slashes Rokkaku down with his axe-hand. The surrounding Marines and Helmeppo gasp in absolute horror. Helmeppo screams that his father didn't have to kill him, but Morgan dismisses it, saying the townsfolk must be taught respect and that he will handle it personally.