With Wang Cai and Fu Duoduo's help, they quickly found the person who had poisoned. The poisoner killed the cook's assistant in the kitchen and then disguised himself as that person, successfully infiltrating the Han Prince Mansion. Before killing the cook's assistant, he had secretly monitored and observed him, only making his move after understanding all of his habits.
After infiltrating the Han Prince Mansion, his character, actions, habits, etc., were no different from the cook's assistant, so no one in the kitchen noticed that the cook's assistant had been swapped.
After the assassin turned into the cook's assistant, he did not poison immediately; instead, he honestly worked as the cook's assistant for some time. The assassin did not act immediately for another reason: Zhao Yao was hardly at the Han Prince Mansion during this period.
