Klein is a policeman. On this day, Klein received a call from the sheriff. He said that the river found a body, and I hope you can investigate the cause of death. Klein goes to the scene and finds this is the only river nearby, and the cordon has set up. According to witness' testimony, he accidentally found the dead body while fishing and then called the police. According to the forensic identification, the time of death occurred last night, and the witness possessed an alibi, which can temporarily rule out suspicion. At this time, you plan to [[examine the corpse]], [[ask witnesses]], or [[inquire about the deceased's information from other policemen]].This is a male corpse, about twenty years old, with a student's backpack on him. Several bruises were found on the corpse's head and back, but there were no other injuries. According to the evidence given by forensic doctors, the cause of death was drowning, not these bruises. Klein opened his [[backpack]].Klein asked the witness how the body was found. Witness told Klein that it was early in the morning, and when he arrived here, he found something floating in the lower reaches of the river. When he walked along the river bank and found that it was a dead body, he immediately called the police. Then, Klein asked whether he knew the deceased. The witness said he did not know the deceased, but sometimes the deceased was seen carrying a [[backpack]] into the woods nearby.
Other policemen told Klein that they had obtained the information from the deceased's [[backpack]]. The deceased was twenty years old and a college student. They have contacted [[the college]] and told his [[parents]] at the same time.There is a [[notebook]] and student ID in the schoolbag. The name of the deceased on the student ID is Tom.Many dates, numbers and symbols are recorded in the notebook. You don't understand what these mean. According to the school title of the notebook and the student ID, Klein decides to to to [[the college]].Klein comes to the college and asked several instructors who have impressions of Tom. Especially the teachers in this semester. Several of Tom's teachers said that Tom's attendance rate was terrible. Also, an instructor said that Tom's group members sent her an e-mail reaction, and Tom often did not participate in the group discussion. The group members want to change the group.Klein learned that Tom had bad interpersonal relationships at school. Now, Klein decided to visit Tom's [[parents]].Klein visits Tom's parents. The couple looks sad, but they don't seem to be surprised by Tom's death. Klein asks Tom's parents whether they know what Tom had good friends and what they usually do. Tom's father said that the husband and wife are both busy with work and do not understand Tom's daily life. Tom's mother said that Tom was often away from home on weekends. Tom had some bad friends. Klein thought that his parents had concealed some information. Because Tom's death did not rule out homicide, Klein enters Tom's [[room]] to investigate.Klein looked up Tom's room and found a notebook hidden in the closet. This notebook is very similar to the notebook in Tom's bag. The contents of the notebook are also numbers, symbols and dates. Klein turned to the last page of the notebook, which was different from the previous one. Symbols and names are recorded on this page. Klein knew that the symbols in the previous notebook represented some people's names. This notebook is an [[accounting book ]].Klein handed the ledger to the sheriff and told the sheriff that it was a ledger and should be related to Tom's death. At the same time, Klein told the sheriff that witnesses had repeatedly seen the dead enter the woods by the river. The sheriff dispatched a police team with dogs to search the woods by the river. The police found some traces of drugs hidden in the woods. According to Tom's social circle and the name provided on the ledger, the police quickly identified the suspect. Tom's member of the same drug gang, because of a dispute, hit Tom and threw him in the river. This concludes the case.