A Bayesian Approach to the Problem of Interpreting Glass Evidence in Forensic Science Casework

A new approach is described to the problem of interpreting the evidential value of glass fragments found on the clothing of a person who is suspected of having committed a crime. The problem is described in a formal sense and a brief review is given of previous papers which have been written on the problem. It is then shown how the Bayesian argument can be applied. Numerical examples are given, based on data abstracted from various sources.     

法庭科学中泥土物证XRF检验数据的分析研判

目的 对元素分析产生的大量数据进行统计,从而达到准确对样品进行区分和归类的目的.方法 利用X射线荧光光谱法对从北京郊区10个区县、辽宁沈阳、安徽泗县、四川泸州、山东威海和广西南宁提取的225个泥土样品进行元素定量分析.采用SPSS软件中欧氏距离计算泥土样品间的差异,利用主成分分析法进行样品归类.结果 确定了不同空间距离样品间差异的欧氏距离的阈值.主成分分析法可对225个泥土进行较为准确的分类.结论 欧氏距离值可为泥土样品的比对提供量化比对依据,利用主成分分析法可推断未知泥土样品的来源.     

Statistical Discriminant Analysis in Forensic Science

A recent paper in the Journal of the Forensic Science Society [1] described a well-known statistical method for addressing the problem of discrimination of cat and dog hairs. It used a so-called “parametric” method which assumes that the observations are Normally distributed and estimates the parameters of the distribution from the data. The present paper describes another method of statistical discrimination known as the kernel method which dispenses with the assumption of Normality. The data alone determine the form of the distribution of the data and therefore multimodal or skew distributions may be more accurately modelled. The kernel method is applied to the data given in [1] and the results obtained compare favourably with those given in that paper.     

Radiocarbon Analysis of Human Remains: A Review of Forensic Applications

Radiocarbon analysis of organic materials, with the comparison of values with those of the post‐1950 modern bomb curve, has proven useful in forensic science to help evaluate the antiquity of evidence. Applications are particularly helpful in the study of human remains, especially with those displaying advanced decomposition of soft tissues. Radiocarbon analysis can reveal if the remains relate to the modern, post‐1950 era and if so, also provide information needed to evaluate the death and birth date. Sample selection and interpretation of results must be guided by knowledge of the formation and remodeling of different human tissues, as well as contextual information and the approximate age at death of the individual represented. Dental enamel does not remodel and thus captures dietary radiocarbon values at the time of juvenile formation. Most other human tissues do remodel but at differing rates and therefore collectively offer key information relative to the estimation of the death date.