Why do fortune tellers know murderers in many cities?

The two played together since childhood. The fortune teller is a character in the TV series "Under the Numerous Cities". The murderer refers to Wei magistrate of a county, that is, Lu Buyou. In the play, the fortune teller and Lu Bu-you played together since childhood, but Lu Bu-you disappeared after Lu Jia was exterminated, and Lu Bu-you became the magistrate of Wei State in order to avenge Lu Jia. The fortune teller and Lu Bu haven't seen each other for some time, but they still recognize that Wei Zhifu is Lu Bu You and know that Lu Bu You is the murderer.