I'm Dark Under the Light of Sin

This should be combined with the introduction to know the general content of the novel: A habitual murderer (nicknamed: Madman Wu) killed a pedestrian and a driver on the 5th of last month, and faked the murder scene: the victim was hit by a car at night without paying attention. Then he repeatedly provoked the police and claimed that he was guilty and wanted to surrender. However, the evidence held by the police indicated that the case had nothing to do with Madman Wu, and they believed that he was mentally ill. Before this, a little girl named Zhu Xiaoya saw the whole process of the case. Two months later (this... Feels a bit buggy) she and her mother went to the police station to record a statement. At this time, Madman Wu broke into the police station again to "provoke". He deduced from the police that someone had seen him commit the crime. When Madman Wu came out of the police station, he saw Zhu Xiaoya and looked at each other on a rainy day. Then do it secretly. The next day, Zhu Xiaoya disappeared. . .