Previously, Nikolay suggested that Pyotr use Shatov’s defection from the group—and his refusal to answer Pyotr’s purity test for revolutionaries—as grounds to justify his murder. In Pyotr’s plan, by murdering Shatov, the group of five would become complicit in a murder, and Pyotr could then use that information to blackmail the people in the group to make sure they stay loyal to him.