现场痕迹从形成到对其进行勘验、检查、检验、鉴定前,不可避免地会受到各种自然因素和人为因素的影响,从而受到不同程度的污染和破坏。这些变化和破坏不仅对现场痕迹的发现、显现、固定、提取、保存具有很大的影响,而且还直接关系到痕迹检验结论的正确可靠与否,从而影响现场痕迹的证据效力。刑事技术人员必须加强对痕迹形成后变化机理的研究,明确引起痕迹变化的因素,采取人工、技术等各种措施尽可能减少或消除痕迹形成后的变化。 Site traces from the formation to its inspection, inspection, inspection, identification, will inevitably be subject to a variety of natural and human factors, which are subject to varying degrees of pollution and destruction. These changes and damages not only have a great impact on the spot discovery, appearance, fixation, extraction and preservation of the spot, but also have a direct impact on the correctness and reliability of the conclusion of the trail inspection, thereby affecting the evidential effectiveness of the spot traces. Criminal technicians must strengthen the research on the mechanism of change after the formation of the marks, clarify the factors that cause the marks to change, and adopt various measures such as manpower and technology to minimize or eliminate the changes after the marks are formed.