Who does Otis amber accuse of being the bomber?

Otis Amber accuses Sam Westing of being the bomber in the novel "The Westing Game." He believes that Westing orchestrated the bombing as part of his elaborate scheme to bring together the heirs and challenge them to solve his mystery. Otis’s accusation stems from his interpretation of the clues and the events surrounding the Westing estate. Ultimately, the mystery unfolds to reveal deeper truths about the characters involved.