摘要
指纹是少数可以直接认定人身的法庭科学物证之一,在侦查破案及法庭诉讼中发挥重要作用。目前指纹只有三种鉴定结论,认定、否定和不够条件。长久以来,现场指纹存在着大量不够鉴定条件的指纹并被废弃不用,但这些指纹具有重要的侦查及应用价值,采用概率化的表达方式可以让这些指纹发挥重要的证据作用。本文阐述了一种对指纹进行扇形分区划分和特征统计的数学建模方法,研究统计了1 500万枚指纹图像的特征分布,拟合出各个扇区内部特征的概率密度函数,并采用贝叶斯准则和添加噪声进行修正,最终得出指纹鉴定结论的概率。本研究所计算出的指纹鉴定概率与指纹匹配特征点的数量、价值及特征稳定度成正相关,与扇区内部特征出现的概率成负相关,能够在一定程度上解决指纹匹配特征的相似概率问题,为指纹鉴定提供了新的思路与办法。研究结果能够使大量不够鉴定条件的指纹重新发挥证据价值,使指纹鉴定从定性走向定量。指纹鉴定结论概率化表达方式结合其他法庭科学证据进行量化分析,在认定犯罪嫌疑人方面具有巨大潜力,是法庭科学发展的新趋势。
Fingerprint,one kind of the most important forensic evidence,is capable of having an individual identified.Therefore,it has played a crucial role in a police investigations and court litigation since it was admitted under jurisprudence.Regarding the verdict of fingerprint identification,there are currently only three propositions in China:recognition,exclusion,and inconclusiveness.Presumably,such handling roots its basis on the experience and practical situation of China’s crime prevention and court processing hitherto,yet having caused abandonment or unusedness of amount-huge fingerprints collected of less than 8 minutiae from crime scenes due to their disqualification to the requirements of source threshold for fingerprint identification.However,these fingerprints are significant for police investigation and court processing.Thus,a probabilistic approach was described here with mathematic modeling to count minutiae by the related fingerprint image divided into fanshaped sectors.Based on the statistics of 15 million fingerprint images,a function of probability density was fitted into fingerprint minutiae of all fan-shaped sectors and then modified under Bayesian Information Criteria,plus the addition of noises.Consequently,a probability was acquired towards identity recognition about a fingerprint under scrutiny.Through a trial of several examples,the results showed that the matching probability of fingerprint pairs was positively correlated to the quantity and stability of the analyzed minutiae yet negatively to the incidence of minutiae occurring inside the fanshaped sectors.This study provided a novel attempt to rediscover the evidential value of those ’useless fingerprints’ displaying no sufficient details for identification but frequently found at crime scenes.Such an approach should be a crucial step for fingerprint identification from quality to quantity analysis,having significant potential to identify a criminal in combination with the quantifying applications of other forensic evidence.
作者
马荣梁
刘寰
吴春生
MA Rongliang;LIU huan;WU Chunsheng(Institute of Forensic Science,Ministry of Public Security,Beijing 100038,China;Beijing Police College,Beijing 102202,China)
出处
《刑事技术》
2023年第1期1-9,共9页
Forensic Science and Technology
基金
国家重点研发计划(2018YFC0807205)
公安部科技强警基础工作专项(2019GABJC19)
中央级公益性科研院所基本科研业务费专项资金项目(2022JB028)。
关键词
指纹鉴定结论
指纹特征
概率
数学模型
证据价值
ngerprint identification conclusion
fingerprint characteristics
probability
mathematic model
evidential value
