1. The case occurred in 199 1 year. At that time, China's social and economic development was relatively backward, and China's criminal investigation methods were also relatively backward, which made it more difficult to detect cases. Without high-tech means of escape, it would be as difficult as looking for a needle in a haystack if only police officers manually touched the platoon one by one. Moreover, due to the backward social management system in China at that time, it was not necessary to use ID cards to take trains, shuttle buses and other means of transportation, so it was easy for fugitives to escape from one place to another without being found. And China at that time? Eye of the sky? The video surveillance system has not been established, and the police can't monitor and investigate the floating population through video surveillance, which makes the pursuit of suspects part-time. Blind? .
The second is to cover up the relatives and friends of the suspect. As we all know, people are gregarious animals, so it is impossible for a suspect to contact his former relatives and friends, but the people who have contact with him did not take the initiative to expose them, so even if there may be clues to catch up with the suspect, they will be lost in the cover-up of relatives and friends.
Third, in the case that the backlog of cases has not been broken for many years, although the local police will rearrange the files every year, they will not attach great importance to it and will not arrange the main force to detect cases. It is reported that the detection of this case was carried out by the Shanghai police this year? Yun Jian -2020 Special Action to Solve Cumulative Murder Cases? Only detected in the middle.