Legal analysis: Documentary evidence refers to written materials or other material materials that prove the true situation of a case with its recorded contents and reflected ideas. When understanding the concept of documentary evidence, we should fully note that modern advanced technology provides more and more means for people to communicate with each other. As we all know, documentary evidence is usually expressed in words, but it can also be charts or symbols. The common tools for forming documentary evidence are paper and pen, but they are not limited to this. Physical evidence refers to all items and traces that prove the true situation of a case. Such as crime tools, stolen money, fingerprints, footprints, objects infringed by criminal acts, articles produced by criminal acts, etc., may expose the crime and capture the physical objects and traces of criminal suspects. The characteristics of material evidence are proved by its external characteristics, article attributes and existence conditions. Physical evidence is objective and easy to verify. It is not only widely used in proving activities, but also plays an irreplaceable role in other evidences. For example, clues can be provided to determine the direction of investigation, and sometimes cases can be cracked and suspects arrested with the help of physical evidence; Physical evidence can be used to identify the authenticity of other evidence; Urge criminal suspects and defendants to confess their crimes, etc. Collecting material evidence is an important duty of public security and judicial organs. The collection of material evidence is mainly carried out by means of inquest, inspection, search and seizure. The material evidence collected and retrieved shall be the original. Only when the original object is inconvenient to carry, unsuitable for preservation or should be returned to the victim according to law can photos and videos reflecting the shape or content of the original object be taken. Photographs and videos of material evidence have the same probative force as the original only if they are checked correctly with the original or verified by identification. Photographs and videos of material evidence shall be taken by at least two producers, accompanied by a written description of the production process and a description of the storage place of the original materials, and shall be signed or sealed by the producers. All the collected physical evidence should be properly kept, and no one can use it, let alone destroy it; Physical evidence that may cause environmental and spiritual pollution shall be preserved and disposed of in accordance with relevant regulations. Physical evidence that can be attached to a case shall be attached for preservation. When transferring a case, the material evidence shall be transferred together with the case file.

Legal basis: Article 50 of the Criminal Procedure Law of People's Republic of China (PRC), all materials that can be used to prove the facts of a case are evidence. Evidence includes: (1) physical evidence; (2) Documentary evidence; (3) Testimony of witnesses; (4) the victim's statement; (5) confessions and excuses of criminal suspects and defendants; (6) Appraisal opinions; (7) Records of inquests, inspections, appraisals, investigations and experiments; (8) Audio-visual materials and electronic data. The evidence must be verified before it can be used as the basis for finalizing the case.