Research On Some Trace Evidence

By the development of the times, the dissemination of information become more convenient, the public began to become more aware of the real situation on the investigation of crime. At the same time, the opening of the investigation make criminals can easily obtain the real situation, the skills and the level of anti-detection had a greatly improved, brought new difficulties and challenges to the cases investigation department of the public security organs. With the traditional investigative techniques’opening, the traditional sense of the evidence in the case of on-site are more and more difficult to find, however, by the technology continues to develop, many new technology began to be applied to the investigation, and in all of this, The use and interpretation about trace evidence, are gradually become exposed, confirmed an important aspect of crime. This article explored three different trace evidences and obtained relevant conclusions, in order to provide some references for the determine of trace evidence.Part Ⅰ:Research of appeared about filed convex text on plastic material, plastic synthetic material are widely used in many aspects of life. Many information are always casted on most of the plastic shell. In robbery and other cases, the perpetrators will damage the text on the stolen goods immediately, such acts cause a great difficult to detection the cases. So the recognition about the damaged text can provide a scientific basis for the investigation of the case, trial and conviction and sentencing. This study explored the reason of reappearing of the damaged text by heating and what problem should pay attention to.Part Ⅱ:Contemporary researches on gunshot residue focus on existence of nitrite. However, previous researches can just make sure that 72 hours is retention time of nitrite, no researches on precision of this time periods have been done. The present study aims investigating variation pattern of nitrite content as the extension of shot time, providing evidence for accurate inference of shot time.Part Ⅲ:testing of β-dope,β-dope have a strong stimulating effect on the human’s body as an adrenergic stimulants, and also have serious side effects. With the increase in the illegal use of β-dope, With the increase of the illegal using about β-dope, and the increase of added means, a higher requirement about how to test β-dope more accurately are demanded. This research is from analog samples, and optimizing the conditions of the ammonium acetate extraction, and get the greatest degree of excluding interference of impurities. The whole process of measurement consumed the least solvent and derivatization reagent. By the recovery experiment and the calculation of relative standard deviation, the results show that this method is accurate and reliable about clenbuterol determination in muscle tissue.