In the spring of 1997, Shanghai became warm at night, but the streets in Shanghai seemed deserted at night. Even if pedestrians can be seen on the street in Yangpu District at night, most of them are accompanied by one or two men and a woman in a hurry. What makes people so nervous? On March 8, 1997, when it was stormy that night, the police on duty at Yangpu District Police Station received a report. A man claimed that his wife was killed on her way home. The deceased was Ms. Hu, a vegetable vendor who lived with her husband in Yangpu District. According to Ms. Hu's husband, the couple sell vegetables in different places. The weather was bad that day, but his wife didn't come home after closing the stall in advance. He called his neighbors to help him find them, but only found his wife's body.

Ms. Hu died in a construction site not far from her home. The fatal wound was a blow to the back of her head and her belongings were taken away. The police initially suspected that this was a murder for money. Just when the case was inconclusive, another tragedy happened. Just two days after Ms. Hu's case happened, that is, on March 21, Ms. Shi, 41, died downstairs at home. In the evening, Ms. Shi had dinner with her colleague. She came home from the hotel at ten o'clock in the evening and went downstairs to the community, only to find that she had forgotten the key to the unit door and asked her husband to drop it from the balcony on the sixth floor. After losing the key, the husband didn't see his wife upstairs, so he went downstairs to check, only to find her dead downstairs.

Ms. Shi, who was covered in blood, was also robbed of her property. The police thought of the murder of Ms. Hu and suspected that it was the same person, but the clues were insufficient. At this time, tragedy happened again. On March 22, two days after Ms. Shi was killed, Ms. Zheng, 44, who lives in Yangpu District, was attacked in the head on her way home. Skull fracture died and her personal belongings were taken away. In the next few days, women were victimized one after another in Baoshan District. The crime method was to hit the victim's head with a blunt instrument, making him unconscious or dead, and then taking away the property. From the first case to April 6, there were 12 middle-aged women victims, which caused panic and great pressure to the police.

The "head-bashing ghost" lurking at night wandered around Yangpu District and Baoshan District, and it was difficult for the police to find its trace for a while. Subsequently, the police quickly set up a major crime unit to investigate these cases. The target of this "hammerhead ghost" is mostly a short middle-aged single woman, and the time of committing the crime is chosen at night in a remote and sparsely populated place. Presumably, the murderer should have committed the crime alone. According to the victim's head trauma, the murder weapon should be waving a blunt instrument.

After that, the police drew a portrait of the suspect. The killer is about 1.7 meters tall. The purpose of the crime is to rob money and flee between Yangpu District and Baoshan District. It is preliminarily inferred that he is a foreigner living or working between two districts with low living standards. In addition, a 47-year-old victim survived the rescue and provided clues to the police, saying that a man with a height of 1.7 meters had been following her after work.

She tried to get rid of the man, but the man bumped into her, and then they quarreled. The man spoke nonstandard Mandarin. The police have more clues. When preparing to catch the murderer in one fell swoop, the "hammerhead ghost" at night committed crimes during the day. This time, the victims were two 61-year-old people resting on a park bench. The murderer knocked them unconscious and stole a gold pendant from the old woman. Only the gold pendant is engraved with the word "bright moon", which is the name of the old woman's son. Then the police followed this clue and found the trace of the murderer.

The police learned in a gold shop that a foreign man had repaired a gold pendant with the word "bright moon" engraved on it. Based on these clues, the police quickly launched an investigation and finally locked in a person named Wei Guangxiu. This person is from Anhui and has a criminal record. On the evening of April 5, the police touched Wei Guangxiu's home in Baoshan District and arrested him in one fell swoop. Wei Guangxiu also has a wife and children at home. It is said that he committed a crime because he had no place to make a living after he got out of prison.

However, for whatever reason, the violator will be punished in the end, and Wei Guangxiu was sentenced to death.