Integration of Pore Features into the Evaluation of Fingerprint Evidence*

Fingerprint practitioners rely on level 3 features to make decisions in relation to the source of an unknown friction ridge skin impression. This research proposes to assess the strength of evidence associated with pores when shown in (dis)agreement between a mark and a reference print. Based upon an algorithm designed to automatically detect pores, a metric is defined in order to compare different impressions. From this metric, the weight of the findings is quantified using a likelihood ratio. The results obtained on four configurations and 54 donors show the significant contribution of the pore features and translate into statistical terms what latent fingerprint examiners have developed holistically through experience. The system provides LRs that are indicative of the true state under both the prosecution and the defense propositions. Not only such a system brings transparency regarding the weight to assign to such features, but also forces a discussion in relation to the risks of such a model to mislead.     

Estimate of the random match frequency of acquired characteristics in a forensic footwear database

When analyzing footwear impression evidence, a significant task of the forensic examiner is to determine if a questioned impression could have originated from a known shoe. To form this opinion, examiners typically evaluate the similarity, quantity, and quality of shared class characteristics and characteristics of use. Since these criteria are developed through training and experience, and therefore purported to be subjective in nature, the opinions formed regarding footwear evidence can be misunderstood. One way to mitigate this criticism is to complement casework with research that includes quantitative analyses. The aim of this study was to estimate random match frequency of randomly acquired characteristics (RAC-RMF) in a research database comprised of 1,300 outsoles with more than 80,000 RACs. Based on a combination of visual comparisons (>91,000) and mathematical predictions (>3.8 million), results indicate that 32% of the outsoles in this dataset do not share any indistinguishable RAC pairs with each other, while 19% possess RAC-RMFs of 1 out of 1,299. At the other extreme, the maximum RAC-RMF observed was 49 out of 1,299. These results are based on high-quality test impressions, human assessments, and a single quantitative similarity metric, so they are considered specific to this dataset and method of analysis. Results could differ in other databases and with impressions of lower quality, and therefore should not be extrapolated to casework. Despite this limitation, the results provide a point of reference for how often RACs may repeat in position and geometry on non-mated outsoles, therefore forming the basis for future research.     

A study on the use of photopolymer reflex plate in the forgery of Chinese seals

This study compares the identifying characteristics between the impressions made with original Chinese seals and photopolymer replicate seals, and between the impressions made with two photopolymer replicate seals that originate from one single negative. Various seal materials common to the Chinese community such as cow's horns and ivory are employed. Other than the common factors such as different incident angle upon imprinting or different degree of inking that constitute the natural variation in impressions, the physical changes of the seal materials with temperature will be considered. This study concludes that photopolymer replicate seal impressions can be differentiated from the originals in respect to print density and stroke morphology, but it is very difficult to differentiate between two photopolymer replicate seal impressions with the same origin. This study also proposes a simple method for the examination of forged Chinese seal impressions.     

利用IDMH-Z780系统对碳素钢笔水书写字迹与印章印文交叉时序的无损检验研究

目的研究常见的碳素钢笔水书写笔迹与不同印章印文交叉时序的相关性。方法利用IDMH-Z780系统对制成的实验样本进行微观观察,并对三维数学模型图进行特征分析。结果先墨后朱,交叉部位字迹边缘状态完整,等高线宽度、流向未见明显变化;先朱后墨,书写笔迹色料分布发生数字图形曲面变化。结论用IDMH-Z780系统可以观察分析朱墨交叉部位的微观特征和无损检验研究。     

印文鉴定相关问题探讨——高仿真印文鉴定

当前,与印文鉴定相关的并在鉴定实践中经常遇到的新问题和难点问题有高仿真印文的鉴定、变造印章问题、利用真实印文变造文件、同版印章印文、朱墨时序等,本文就高仿真印文的鉴定进行了系统阐述,介绍了各种高仿真印文,包括各种高仿真印章的盖印印文、复制印文、转印印文的伪造手段及其特点,并提出了高仿真印文的鉴定思路和要点。     

傅立叶显微红外化学成像在朱墨时序鉴定中的应用研究

目的建立朱墨时序的傅里叶显微红外成像检验方法。方法根据印文及油墨的红外光谱特征峰,使用傅立叶变换红外（FTIR）成像系统直接对纸张上印文及文字油墨进行化学成像,根据成像特征从而判断朱墨时序。结果先打印后盖章的红外成像中油墨字迹的红外成像不完整,有被印章所覆盖的痕迹,而印章的红外成像完整,在字迹中可见印章成像斑点。先盖章后打印的红外成像中油墨字迹的红外成像完整,没有被印章所覆盖,而印章的红外成像不完整,被字迹的油墨所覆盖。结论该方法较传统的鉴定方法更加快速、简单,可以更加直观的反映行文顺序,并且具有不破坏检验样本的特点。     

Chemical enhancement of footwear impressions in blood on fabric — Part 3: Amino acid staining

Enhancement of footwear impressions, using ninhydrin or ninhydrin analogues is not considered common practice and such techniques are generally used to target amino acids present in fingermarks where the reaction gives rise to colour and possibly fluorescence. Ninhydrin and two of its analogues were used for the enhancement of footwear impressions in blood on various types, colours and porosities of fabric. Test footwear impressions on fabric were prepared using a specifically built rig to minimise the variability between each impression. Ninhydrin enhancement of footwear impressions in blood on light coloured fabric yielded good enhancement results, however the contrast was weak or non-existent on dark coloured fabrics. Other ninhydrin analogues which have the advantage of fluorescence failed to enhance the impressions in blood on all fabrics. The sequential treatment of impressions in blood on fabric with other blood enhancing reagents (e.g. protein stains and heme reagents) was also investigated.     

文件形成时间鉴定的统计学方法初探

文件形成时间的鉴定问题一直是文书鉴定领域最具争议和挑战的疑难问题．尤其是如何利用文件要素与时间的关系,定量分析判断文件的形成时间。通过对一起印章印文盖印时间鉴定的实际案例,探讨了如何运用统计学方法定量分析印章印文阶段性特征中的定量特征与印文盖印时间之间关系,为印章印文盖印时鉴定提供一种定量分析的方法,也为如何进一步运用统计学方法定量分析文件形成时间的类似问题提供了一种研究思路。     

Controlling the variable of pressure in the production of test footwear impressions

Footwear impression lifting and enhancement techniques may be affected by several variables introduced during the production of test footwear impressions, thus limiting the usefulness of enhancement technique comparisons and the results obtained. One such variable is the force applied when the impressed mark is being made. Producing consistent test impressions for research into footwear enhancement techniques would therefore be beneficial. This study was designed to control pressure in the production of test footwear impressions when mimicking a stamping action. Twenty-seven volunteers were asked to stamp on two different surfaces and the average stamping force was recorded. Information from the data obtained was used to design and build a mechanical device which could be calibrated to consistently deliver footwear impressions with the same force onto a receiving surface. Preliminary experiments using this device and different contaminants on the footwear sole have yielded consistent and repeatable impressions. Controlling the variable of pressure for the production of test impressions in this study demonstrated that the differences observed were visual (due to the amount of contaminant transferred and subsequent enhancement) and did not affect the replication of outer sole characteristics. This paper reports the development of the device and illustrates the quality of the impressions produced.     

Collection of Wet‐Origin Footwear Impressions on Various Surfaces Using an Electrostatic Dust Print Lifter

Electrostatic dust print lift method is known to be able to recover only dry‐origin footwear impression. However, the wet‐origin footwear impression could also be recovered using this method. As the amount of dust accumulated before deposition of the wet‐origin footwear impression increased, the intensity of the footwear impression lifted with this method became stronger. If the footwear impression is not affected by moisture after it is made, the 28‐h old wet‐origin footwear impression could be recovered using this method. The intensity of the lifted footwear impression did not decrease significantly even when the number of sequential steps increased as long as the shoe sole is wet. However, when the moisture on the shoe sole depleted, the intensity of the footwear impression decreased sharply. This method has the advantage of being able to enhance the footwear impression without being affected by the footwear impressions deposited in the past.     

Secondary impressions of writing detected by ESDA

Experiments have been performed which show conclusively that, under certain conditions, ‘impressions’ of writing can be detected by ESDA (ElectroStatic Detection Apparatus) on paper which has been placed in contact with the reverse of paper bearing writing which has significantly embossed the back. Such indirect ‘secondary’ impressions are caused by some degree of lateral relative motion of the two sheets of paper. Secondary impressions can usually be distinguished from normal primary impressions (caused by the ‘act’ of writing) by several characteristics, in particular, by the indistinct, incomplete and, sometimes, diffuse nature of the secondary impression images.     

Barefoot impressions--a preliminary study of identification characteristics and population frequency of their morphological features

Footprint impressions of 107 male adults ranging in age from 19 to 67 years were recorded and examined. Included in this study were foot impressions from a pair of monozygotic twins as well. The impressions were recorded and converted into a set of indices which essentially are width-versus-length ratios of prominent features of the human foot. These indices were then correlated to yield probability values for use in this study and for comparison to data published by previous investigators Qamra, Abbott, Lovejoy, Cassidy, and Robbins. Friction ridge minutae were not considered in this study. Crease marks, well impressions, and toe step measurements were considered, but not incorporated in the probability values, because of the unique aspect of these features and the inability, at present, to convert these features to mathematical indices. These features do, however, introduce a subjective nature to the analysis scheme. This study uses the combined index probabilities of foot impressions so that the data generated can be used to assign a given probability that a particular foot impression, even without clear definable individual features, can be linked to the person who made the impression.     

浅谈印章印文的边框特征

本文通过对印章边框特征的产生原理及种类的分析与研究,阐述了影响印章边框特征的因素,提出了应用边框特征检验印章印文应注意的基本事项。     

印油与印油印迹比对检验方法的影响因素研究

目的针对印油印迹形成过程中可能存在的影响因素,研究印油与印油印迹比对分析方法中可能存在的风险。方法采用溶剂提取,高速离心,过膜的简单的前处理方法,然后高效液相色谱分析,用色谱峰峰面积的相对含量来判定印油印迹与印油之间的差异。结论印泥印油、印油印迹与印油之间差异很小;而印台印油、渗透印油、翻转印油、印油与印油印迹比对时,存在一定影响。     

Evaluation and comparison of the electrostatic dust print lifter and the electrostatic detection apparatus on the development of footwear impressions on paper

The Electrostatic Dust Print Lifter (EDPL) and the Electrostatic Detection Apparatus(2) (ESDA(2)) were compared to determine if both processes could be used to develop footwear impressions of the same or similar quality and in what order they should be used to develop the highest quality footwear impression. The sensitivity of each technique was also evaluated. The quality of the footwear impressions developed was determined by comparing 25 individual characteristics present on the known shoe to the footwear impressions developed using each technique. The footwear impressions were made by stepping on paper placed over several different surfaces, which included: linoleum, industrial Berber carpet, nylon carpet placed over a (3/8)-in. pad, ceramic tile, cardboard, 1-in. foam, 4-in. foam, cement, asphalt, grass, and mulch. Each of the papers placed on these surfaces was developed using the EDPL before the ESDA(2) and vice versa. The sensitivity test for the ESDA(2) was conducted by processing 10 sheets of stacked paper that were stepped on with the known shoe, beginning with the top sheet. The sensitivity test for the EDPL was conducted by processing 10 sheets of paper stepped on with the known shoe in succession. This study determined the footwear impressions developed using the EDPL were of better comparative value than impressions developed with the ESDA(2). On average, 72.4% of the individual characteristics from the known impression were identified on images developed when the EDPL was used first compared with an average of 38.9% when the ESDA(2) was used first. Therefore, if only one technique is used, the EDPL should be chosen. The sensitivity test determined the ESDA(2) develops high-quality footwear impressions on only the top sheet of paper. No footwear impressions were developed on any sheets under the top sheet of paper. The sensitivity test also determined the EDPL results increase in quality as the amount of dust residue decreases on the surface.     

Classification of firing pin impressions using HOG-SVM

Crimes, such as robbery and murder, often involve firearms. In order to assist with the investigation into the crime, firearm examiners are asked to determine whether cartridge cases found at a crime scene had been fired from a suspect's firearm. This examination is based on a comparison of the marks left on the surfaces of cartridge cases. Firing pin impressions can be one of the most commonly used of these marks. In this study, a total of nine Ruger model 10/22 semiautomatic rifles were used. Fifty cartridges were fired from each rifle. The cartridge cases were collected, and each firing pin impression was then cast and photographed using a comparison microscope. In this paper, we will describe how one may use a computer vision algorithm, the Histogram of Orientated Gradient (HOG), and a machine learning method, Support Vector Machines (SVMs), to classify images of firing pin impressions. Our method achieved a reasonably high accuracy at 93%. This can be used to associate a firearm with a cartridge case recovered from a scene. We also compared our method with other feature extraction algorithms. The comparison results showed that the HOG-SVM method had the highest performance in this classification task.     

文件朱墨时序的检验方法及其比较分析

文件朱墨时序的判定是文件检验领域的难题之一。本文以38篇文献为基础,综述了目前常用的解决朱墨时序问题的十一种方法。并对各种方法的适用范围、优点和局限进行比较分析,以期为文检工作者视检材的具体情况采用合适的检验方法,提供一些参考。     

A comparison of three shoe sole impression lifting methods at high substrate temperatures

Footwear impressions are a common form of evidence found at crime scenes, and the accurate recovery and recording of such impressions is critical for shoe sole comparison and identification. The lifting of shoe sole impressions from hot surfaces (>30°C/86°F) and in hot environments has received little attention in the literature, particularly in relation to the recovery of class and randomly acquired characteristics (RACs) required for accurate comparisons. This study addressed this knowledge gap by comparing the performance of three common impression lifters (gelatin, adhesive, and vinyl static cling film) at recovering shoe sole impressions in dust from hot flooring substrates. Dry origin dust shoe sole impressions were made on ceramic tile, galvanized metal, and laminated wood flooring using a shoe that possessed two RACs and five class characteristics present on the sole. Substrates were left in direct full sun for five hours during a summer day prior to lifting. Performance was measured by the proportion of RACs and class characteristics visible in each lifted impression. Results demonstrated that the vinyl static cling film tested performed poorly across all substrates, particularly for metal (23.8% marks recovered), including notable shrinkage of the lifted impression. In contrast, adhesive (~96% marks recovered over all substrates), and to a lesser extent gelatin (~85%), lifts were highly successful on hot substrates. These data suggest that adhesive lifts can consistently and accurately recover shoe sole impressions from hot substrates. This study contributes critical information for crime scene examiners to improve and expand evidence recovery in hot environments.     

公章抗辩的类型与处理

公章的意义在于使特定的意思表示与特定的主体相联结,是书面法律行为的重要标识方式。因经济活动中存在真公章无权使用和假公章冒用等现象,公章名义人因此或借此对公章真假及使用效力提出抗辩。但实践中对公章效力的判定却常有偏差,其重要原因之一就是对公章抗辩缺乏系统有效的处理规则。公章抗辩包括公章确认抗辩和公章效力抗辩,公章效力抗辩又可分为真公章效力抗辩和假公章效力抗辩。不同类型的公章抗辩在抗辩事由、举证责任等方面,均有不同的规则内容与处理要点。实务中对公章抗辩的处理与认定,应当有效把握不同公章抗辩类型的基本规则与特殊情形,并妥当辨识及运用公章效力与表见代理或表见代表之间的互证关系。