Statistical Discrimination of Footwear: A Method for the Comparison of Accidentals on Shoe Outsoles Inspired by Facial Recognition Techniques

Abstract:  In the field of forensic footwear examination, it is a widely held belief that patterns of accidental marks found on footwear and footwear impressions possess a high degree of "uniqueness." This belief, however, has not been thoroughly studied in a numerical way using controlled experiments. As a result, this form of valuable physical evidence has been the subject of admissibility challenges. In this study, we apply statistical techniques used in facial pattern recognition, to a minimal set of information gleaned from accidental patterns. That is, in order to maximize the amount of potential similarity between patterns, we only use the coordinate locations of accidental marks (on the top portion of a footwear impression) to characterize the entire pattern. This allows us to numerically gauge how similar two patterns are to one another in a worst-case scenario, i.e., in the absence of a tremendous amount of information normally available to the footwear examiner such as accidental mark size and shape. The patterns were recorded from the top portion of the shoe soles (i.e., not the heel) of five shoe pairs. All shoes were the same make and model and all were worn by the same person for a period of 30 days. We found that in 20–30 dimensional principal component (PC) space (99.5% variance retained), patterns from the same shoe, even at different points in time, tended to cluster closer to each other than patterns from different shoes. Correct shoe identification rates using maximum likelihood linear classification analysis and the hold-one-out procedure ranged from 81% to 100%. Although low in variance, three-dimensional PC plots were made and generally corroborated the findings in the much higher dimensional PC-space. This study is intended to be a starting point for future research to build statistical models on the formation and evolution of accidental patterns.     

“Bubbles”—A Spot Diagnosis

Abstract: Aspiration of blood is a phenomenon observed in violent and natural death scenarios. Bloodstain patterns evolving from expectoration of aspired blood may look suspicious of a violent genesis and thus mislead crime scene investigators. In the present case, a woman was found lying in a pool of blood on the kitchen floor. Furthermore, bloodstains covered her face, clothing, and surrounding furniture and walls. Bloodstain pattern analysis and medicolegal inspection of the suspected scene of crime were carried out and revealed dispersed stains with enclosed gas bubbles in the absence of signs of physical violence leading to the assessment of a natural manner of death. The bloodstains were attributed to expiration of blood because of an internal bleeding. Medicolegal autopsy confirmed the on‐site diagnosis as a fatal esophageal varix rupture was found.     

入室作案现场残缺鞋印的研究

鞋印是犯罪现场上最常见的犯罪痕迹,但在犯罪现场鞋印经常表现为残缺。分析影响鞋印形成的因素,对残缺鞋印进行认真观察,对其部位及特征进行准确刻画,并进行科学拼接和延展,实现对留痕鞋印进行准确分析,能够为刻画作案人提供有效的依据。     

Source Camera Identification for Heavily JPEG Compressed Low Resolution Still Images*

Abstract: In this research, we examined whether fixed pattern noise or more specifically Photo Response Non‐Uniformity (PRNU) can be used to identify the source camera of heavily JPEG compressed digital photographs of resolution 640 × 480 pixels. We extracted PRNU patterns from both reference and questioned images using a two‐dimensional Gaussian filter and compared these patterns by calculating the correlation coefficient between them. Both the closed and open‐set problems were addressed, leading the problems in the closed set to high accuracies for 83% for single images and 100% for around 20 simultaneously identified questioned images. The correct source camera was chosen from a set of 38 cameras of four different types. For the open‐set problem, decision levels were obtained for several numbers of simultaneously identified questioned images. The corresponding false rejection rates were unsatisfactory for single images but improved for simultaneous identification of multiple images.     

西方情报主导警务理论的发展脉络

情报主导警务理论从问题导向警务理论中脱胎而出,起源于20世纪90年代英国的肯特郡,完善于英国的国家情报模型的建立,目前正在全球范围内广泛运用。情报主导警务理论代表了信息化时代警务模式的发展方向。     

论语音象似性及其在诗歌文本中的应用

本文通过尝试建立语音象似性的连通主义模型,从本体感受论的角度对语音象似性的客观现实性和心理真实性作了论证;在对诸多有关语音象似性的论述进行总结的基础上,进一步提出语音象似性的二分法并强调语音象似性的意象图式说;由于体现象似性特征的语音模式是诗歌文本序列的构建原则之一,故最后对诗歌文本中的语音象似性进行了探寻.     

Are DNA data a valid source to study the spatial behavior of unknown offenders?

Studying the spatial behaviour of unknown offenders (i.e. undetected offenders) is difficult, because police recorded crime data do not contain information about these offenders. Recently, forensic DNA data has been used to study unknown offenders. However, DNA data are only a subset of the crimes committed by unknown offenders stored in police recorded crime data. To establish the suitability of DNA data for studying the spatial offending behaviour of unknown offenders, we examine the concentration and spatial similarity of detected but unsolved crimes in police recorded crime data (N?=?181,483) and DNA data (N?=?1913) over 27 Belgian judicial districts for four crime types. We established spatial similarity for certain crime types (in some districts). This offers opportunities for DNA data to be used to study unknown offenders' spatial offending behaviour. Implications for theory and research are discussed.     

Determination of firing distance. Lead analysis on the target by atomic absorption spectroscopy (AAS)

This paper reports a method for the determination of the firing distance. Atomic absorption spectroscopy (AAS) was used to determine the lead (Pb) pattern around bullet holes produced by shots on test targets from the gun. Test shots were made with a Colt 38 Special at 5, 10, 20, 25, 30, 35, 40, 45, 50, 60, 80, and 100 cm target distance. The target was created with sheets of Whatman no. 1 paper on a polystyrene support. The target was subdivided into three carefully cut out rings (1, 2, and 3; with external diameters of 1.4 cm; 5 cm; 10.2 cm, respectively). Each sample was analyzed with graphite furnace AAS. Lead values analysis performed for each ring yielded a linear relation between the firing distance (cm) and the logarithm of lead amounts (microg/cm(2)) in definite target areas (areas 2 + 3): [ln dPb(2+3) = a(0) + a(1)l]; where dPb(2+3) = lead microg/cm(2) of area 2 + 3; a(0) and a(1) are experimentally calculated; l = distance in cm.     

西部大开发中建立区域绿色生态经济模式的基本思路

绿色生态经济模式是可持续发展原则的产业化。21世纪,西部区域可持续发展的根本途径是建立绿色生态经济模式。区域绿色生态经济模式建立的基本思路是:实现生态系统与经济系统及开发方式的对接;通过发展农业生态经济,建立区域生态工业经济体系,建立生态化的区域第三产业等,提高区域绿色生态经济的总量与质量。     

两种侦查模式的比较研究

近年来 ,公安部刑侦局试图通过转变侦查模式来解决破案率偏低和破案成本偏高的问题 ,将“从案到人”侦查模式过渡到“从人到案”侦查模式。不少侦查部门因此认为“从人到案”是一种高于“从案到人”的新型侦查模式。事实上 ,“从人到案”不是新型的侦查模式 ,给“从人到案”模式定指标更不合理 ;“从案到人”的侦查模式也没有过时 ,两种侦查模式有各自的适应性。侦查实践中要依据具体情况来确定采用何种侦查模式。