Spring in J City is extremely hot and frustrating. Although the sprouts have not yet sprouted on the branches, the temperature has reached 17, 18 degrees. Cai Wei was sitting in a Jeep speeding down the street, frustratedly unbuttoning his shirt. He was very upset, but not only because of this sweltering spring weather. As a policeman, Thai Wei is facing the most difficult case in his 10 years as a police officer. On March 14, 2002, resident Tran Mo (female, ethnic Han, 31 years old) lives in room 402, building 32, Minh Chau sub-area, 83 Thai Bac street, Hong Vien area, city J. was killed in his apartment. According to the results of the autopsy, the time of death was from 14 to 15 hours, the cause of death was suffocation. On the victim's neck, two marks of strangulation were discovered. Through the investigation of the scene, it was found that there were no traces of being ransacked in the room, and the property was not lost, initially eliminating the possibility of breaking into and killing people and looting. The victim's upper body is bare, the lower body is neatly dressed, there is no sign of sexual abuse, nor does it appear to be a rape murder. The amazing thing is, after the victim died, the perpetrator cut open the abdomen, the knife used to operate was left at the scene. The victim's husband confirmed, this is the knife in the victim's house. The scene of mourning, could not bear to look, on the floor were the organs and blood of the victim. Police found a cup in the kitchen, which, through tests, determined it was a mixture of fresh milk and the victim's blood. This can't help but remind us of the legendary monster - the bloodsucker. In the period of more than a month after that, in J city, there were two consecutive cases of breaking into the house to kill people, the victims were all girls aged 25-35. The victims had their stomachs cut open. At the same time, at the scene, they found a mixture of the victim's blood and other substances