From 65438 to 0985, Professor jeffries, a biologist at the University of Leicester, England, invented the method of DNA identification, which attracted great attention of police all over the world, calling this discovery a revolutionary breakthrough in forensic medicine research. It makes the traditional forensic biological test only exclude the suspect, but not identify the suspect to a new stage. Since then, the research and application of DNA has set off a wave of forensic medicine in various countries. Now, this technology has spread all over the world1more than 30 countries. The Second Research Institute of the Ministry of Public Security of China established a DNA fingerprinting laboratory in 1987, and began to study this technology and apply it to handling cases. Then, Beijing, Liaoning, Jiangsu and other places also used this technology to handle cases and achieved great social benefits.

When people are still in a cell at the beginning of life, they get a "half block" of the "construction drawing" of life from their parents and form their own unique DNA map. There are about 654.38+ten thousand human genetic genes, and each gene is composed of four nucleotides, A, T, G and C, which are arranged in sequence on two complementary DNA long chains to form a spiral structure. The total number of nucleotides is about 3 billion. At present, it has been found that DNA with genetic function is distributed on genetic sites like small satellites. The "small satellites" of the same race all have the same core sequence, which is the material basis of racial inheritance and individual similarity. At the same time, the edge sequence of "microsatellite" is highly variable, and different individuals are different from each other, which is an important internal cause of individual diversity within the race. Commercial bar code strips can be obtained by autoradiography or enzymatic coloration of genes at gene sites. This band, like human fingerprints, varies from person to person and has high specificity, which is the origin of DNA fingerprints.

If two people's DNA is randomly selected as a fingerprint, the exact same probability is only one in 300 billion. This probability is far lower than the reciprocal of the current world population. Even brothers and sisters, the same probability is only one in two million. However, in the core sequence, the maps of the same family are completely consistent, so the children's DNA fingerprints can be accurately reproduced in the parents' core maps, which is the basis of "paternity test".

The identification of the perpetrator by DNA fingerprinting technology is carried out by comparing the on-site biological tests (blood spots, semen spots, tissues, hair, etc.). ) and the suspect's DNA fingerprint. If the perpetrator is not regarded as a suspect, it is impossible to identify the perpetrator. Therefore, some people abroad simply suggest that a national or regional DNA fingerprint database be established on a large scale, and the perpetrators can be directly identified through computer query and comparison. However, this huge project is not easy to implement. At the same time, some people think that it violates citizens' right to privacy. Others worry that if this database is really established, it will be difficult to ensure that some geneticists don't want to carry out experiments on "gene mapping", thus abusing this technology and even bringing disasters similar to Nazi national cleansing to society.

1in July, 1994, the new York state legislature agreed to establish a state-level DNA database after many debates. The database will store DNA samples of convicted felons so that they can be used to determine their connection with pending cases.