23 years ago, a sudden murder occurred in a rented house in Baoshan District, Shanghai. When the police arrived at the scene, what caught their eyes were the victim with a head injury, a bloody stainless steel kitchen knife, a torn contact list, a phone soaked in the basin, and a leftover apple core. Due to technological limitations at the time, the case was not solved for a long time, but the biological information left at the scene was permanently preserved. Until February of this year, the case saw a turning point and the fog was gradually cleared away. The Criminal Investigation Detachment of Baoshan Branch of Shanghai Public Security Bureau, under the guidance of the Criminal Investigation Corps of the Municipal Bureau, has been continuously tracking and recently solved this 23 year old murder case backlog. On the evening of December 31, 2001, the Baoshan police received a report from a public that their friend had been killed in a rented house in a residential area in Baoshan. During the police investigation of the scene, it was found that the deceased, Ms. Huang, was 32 years old and had suffered a head injury. It is speculated that she died at noon on the same day. There was a stainless steel kitchen knife stained with blood at the scene, and the police determined that the rented house was the first crime scene. In addition to the murder weapon left by the perpetrator, the police also discovered torn contact lists, phones soaked in the basin, and a leftover apple core at the scene. The police learned from the caller that the deceased had complex interpersonal relationships before his death, and the contact information of some frequently contacted friends would be recorded in the address book. At the same time, the informant also provided a clue to the police that the deceased never ate apples normally, but had a habit of peeling apples to entertain guests. After inspection, two types of biological traces were left at the scene. Apart from the deceased himself, another type of biological trace is likely to belong to the perpetrator. Based on the above clues, the police have focused their investigation on the crime committed by acquaintances. On the one hand, the police ruled out the suspect of the crime through blood type comparison and alibi. On the other hand, the police retrieved the last call sign record of the deceased's mobile phone from the communication company and locked it onto a public phone from a nearby tobacco store. According to the recollection of a staff member at the tobacco and miscellaneous store, a man in his forties, with a slim figure, wearing a dark jacket, and with an accent from Nantong, Jiangsu, called at noon that day. Criminal investigation experts drew a simulated portrait based on physical characteristics. The police carried this portrait and conducted a sweeping visit to 39 residential buildings and a 5-kilometer radius around the crime scene, but found no results. The collar of the uniform guides the direction of the case. Due to the delay in identifying the portrait, the investigators believe that the suspect may not be a nearby resident, so they have shifted the investigation direction to the suspect's profession. The investigators started with the collar of the jacket on the simulated portrait and collected a large number of mainstream uniform samples in society at that time. Combined with the characteristics of Baoshan area, they speculated on the possible occupation of the suspect: taxi driver, metallurgical worker or construction worker. The investigators spent three months visiting over 1400 taxi drivers with portraits of the suspects; Conducted comprehensive visits to approximately 1000 employees with accents from the Nantong area of metallurgical enterprises in the vicinity of the case site; More than 100 migrant workers with accents from the Nantong area were surveyed one by one at a construction site adjacent to the crime scene. On this basis, the police have sorted out the residential and hotel registration information around the crime scene in the past six months, but have not found any clues to the investigation. Over the next 20 years, the Criminal Investigation Detachment of Baoshan Public Security Bureau organized investigators to conduct retrospective research every year. Based on the coverage of the investigation that year, they expanded the investigation line to include former and retired employees and their families of relevant units. They also organized police officers to conduct continuous investigations in Jiangsu, Zhejiang, Shanghai, Anhui and other places. With the passage of time, the case files that have accumulated countless days and nights of hard work from generations of detectives have become thicker and thicker, and have also accumulated one "puzzle" after another for one day to solve cases. In recent years, the Baoshan police have integrated science and technology, data application, and investigation work. They continuously and rolling compare biological samples in the system, establish a digital "case file" for paper-based accumulated case materials, innovate image technology for investigation and solving cases, analyze, correlate, and collide massive information data, continuously carry out clue verification and comparison, and continuously improve the precise guidance role of information analysis and judgment. At the end of 2022, the Baoshan police used the latest technology to conduct laboratory analysis on the physical evidence extracted from the crime scene that year, and confirmed their determination that the crime was committed by personnel from Nantong, Jiangsu. Based on this important clue, the Criminal Investigation Detachment of Baoshan Public Security Bureau quickly formed a 5-person investigation team to investigate in Nantong, Jiangsu. Unfortunately, the investigation team has not found the suspect in more than 20 business trips spanning 14 months. If the murder case is not solved, the investigation will continue. In February of this year, the case finally saw a turning point. When investigating a theft case in Jiangsu, the police found that there was biological information highly similar to the suspect in the Baoshan murder case. The Baoshan police immediately rushed to the local area. While investigators were conducting extensive visits and investigations, a village official reported to the police after identifying a simulated portrait that the person looked very much like the deceased villager Shen. After comparing the information in the registered residence file, the police found that Shen's photo and portrait had a high similarity. He was 36 years old when the crime was committed, and his body characteristics were also very consistent with the suspect, but now he is dead. In order to further verify Shen's identity, experts from the Criminal Investigation Brigade of Shanghai Public Security Bureau and the Criminal Investigation Department of Baoshan Public Security Bureau formed a technical team to confirm that Shen's biological information completely matches the biological traces left at the scene of the crime that year, and is exclusive. On this basis, the police continued to visit, verify, and follow up with relatives, friends, and colleagues who were familiar with Shen's situation at that time, based on the electronic case file. According to Shen's relatives and neighbors, Shen had worked in Shanghai for decoration since 2000, and almost never returned to his hometown. At the beginning of 2002, Shen suddenly returned to the village and became cautious. He never went far away again and never mentioned his experience of working in Shanghai until he passed away due to illness in 2015. At the same time, the police also found a colleague who worked with Shen in Shanghai at that time. According to recollection, Shen had been soliciting scattered decoration work in a street garden in Baoshan City for a long time, which was consistent with the deceased's usual activity location. After further scientific comparison, the suspect is really Shen who has died. At this point, the truth behind the 23 year old murder case has been revealed, and the police have also informed the deceased's family and investigators who have handled cases over the years of this news. It is reported that since this year, the Shanghai police have successively solved 8 accumulated homicide cases and arrested 9 suspect, including 4 homicide cases spanning more than 20 years, with the longest time of 33 years. (New Society)