Journey history reconstruction from the soils and sediments on footwear: An empirical approach

The value of environmental evidence for reconstructing journey histories has significant potential given the high transferability of sediments and the interaction of footwear with the ground. The importance of empirical evidence bases to underpin the collection, analysis, interpretation and presentation of forensic trace materials is increasingly acknowledged. This paper presents two experimental studies designed to address the transfer and persistence of sediments on the soles of footwear in forensically relevant scenarios, by means of quartz grain surface texture analysis, a technique which has been demonstrated to be able to distinguish between samples of mixed provenance.It was identified that there is a consistent trend of transfer and persistence of sediments from hypothetical pre-, syn- and post-crime event locations across the sole of the shoe, with sediments from ‘older’ locations likely to be retained in small proportions. Furthermore, the arch of the shoe (the area of lowest foot pressure distribution) typically (but not exclusively) retained the highest proportion of grain types from previous locations including the crime scene. A lack of chronological layering of the retained sediments was observed indicating that techniques that can identify the components of mixed provenance samples are important for analysing footwear sediment samples. It was also identified that the type of footwear appeared to have an influence on what particles were retained, with high relief soles that incorporate recessed areas being more likely to retain sediments transferred from ‘older’ locations from the journey history. In addition, the inners of footwear were found to retain sediments from multiple locations from the journey history that are less susceptible to differential loss in comparison to the outer sole. These findings provide important data that can form the basis for the effective collection, analysis and interpretation of sediments recovered from both the outer soles and inners of footwear, building on the findings of previously published studies. These data offer insights that enable inferences to be made about mixed source sediments that are identified on footwear in casework, and provide the beginnings of an empirical basis for assessing the significance of such sediment particles for a specific forensic reconstruction.     

The transfer and persistence of automotive carpet fibres on shoe soles

The transfer and persistence of automotive carpet fibres to shoe soles was investigated. It was found that fibres were transferred with the normal activity of a car passenger. Carpet type and shoe sole parameters were significant determinants in the number of fibres that transferred. The average number of fibres was between about one and 33 per sole. Fibres that had been transferred after normal activity only persisted for a few minutes after walking. A survey of the shoe soles of people about to leave their car showed that fibres were usually present. The majority of shoe soles surveyed had less than five fibres with the greatest number of fibres found being 14. The likelihood of finding a large number of fibres on such soles is rare. Fibre composition of automotive carpets showed a high degree of variation. Grey was seen to be a common colour irrespective of the colour of the vehicle body.     

The Death of Countess Agusta in Portofino (Northern Italy) and the Soil from Two Mismatched Slippers

Abstract:  Accident, suicide, or homicide might have caused the death of Countess Agusta who fell from the 80-m tall cliff of her villa. Two mismatched slippers were recovered along the cliff. Use was made of microscope, X-ray diffractometry, scanning electron microscopy, and microprobe techniques to compare 40 mg of soil collected from the slipper soles with samples from the villa garden. Structural details of the slipper soles were consistent with the lady wearing them during the fall. Analysis of the soil residues confirmed that they originated from the garden only. The features of a few, minute glass chips adhering to the slipper soles reasonably matched those of other fragments that were found on a small ledge on the cliff beyond the garden parapet. Based on this and other evidence, the case was closed with a verdict of accidental fall.     

汽油中的毒品还原分析

目的建立汽油中海洛因的检验方法及还原方法。方法利用无水乙醇挥发汽油混合物中的汽油,通过TLC、IR、GC、GC/MS对汽油混合物中溶剂和毒品成份进行了定性定量分析。结果利用该方法对涉案检材成功进行了毒品还原及检验分析。结论该方法适合于此类案件检验。     

Finding and identifying text in 900+ languages

This paper presents a trainable open-source utility to extract text from arbitrary data files and disk images which uses language models to automatically detect character encodings prior to extracting strings and for automatic language identification and filtering of non-textual strings after extraction. With a test set containing 923 languages, consisting of strings of at most 65 characters, an overall language identification error rate of less than 0.4% is achieved. False-alarm rates on random data are 0.34% when filtering thresholds are set for high recall and 0.012% when set for high precision, with corresponding miss rates of 0.002% and 0.009% in running text.     

茚三酮显现汗潜指印的三种操作方法对DNA检测的影响

目的探讨并比较茚三酮显现汗潜指印的3种操作方法,即溶液浸泡法、涂抹法和喷雾法对后续DNA检测带来的影响。方法取16名志愿者的指印分4组,分为茚三酮浸泡法、涂抹法和喷雾法以及空白组,然后提取DlNA进行定量和STR分型检测。结果3种操作方法都会减少汗潜指印DNA的量,喷雾法的损失量最大,浸泡法和涂抹法结果比较接近。结论现场可疑指印检材,应根据检验需要决定指印显现和DNA提取的先后顺序。     

Shoeprint image retrieval and crime scene shoeprint image linking by using convolutional neural network and normalized cross correlation

A shoeprint image retrieval process aims to identify and match images of shoeprints found at crime scenes with shoeprint images from a known reference database. It is a challenging problem in the forensic discipline of footwear analysis because a shoeprint found at the crime scene is often imperfect. Recovered shoeprints may be partial, distorted, left on surfaces that do not mark easily, or perhaps come from shoes that do not transfer marks easily. In this study, we present a shoeprint retrieval method by using a convolutional neural network (CNN) and normalized cross-correlation (NCC). A pre-trained CNN was used to extract features from the pre-processed shoeprint images. We then employed NCC to compute a similarity score based on the extracted image features. We achieved a retrieval accuracy of 82% in our experiments, where a “successful” retrieval means that the ground truth image was returned in the top 1% of returned images. We also extend our shoeprint retrieval method to the problem of linking shoeprints recovered from crime scenes. This new method can provide a linkage between two crime scenes if the two recovered shoeprints originated from the same shoe. This new method achieved a retrieval accuracy of 88.99% in the top 20% of returned images.     

Misinterpretation of fetal high voltage and lightning accidents

From medicolegal practice it is known that in deaths caused by low voltage, electric marks may be absent or inconspicuous so that they may remain undetected during the scene examination. That this may happen even in fatal high-voltage accidents is demonstrated by 4 examples from our own autopsy material. The cases reported shared the following features: The decedents were found outdoors under a high-voltage line with a several metres long conductive object being in the immediate vicinity of the body; no extensive burns as those seen after the impact of an electric arc; inconspicuous electric marks on the hands; clearly visible electrothermal skin lesions limited to body regions covered by clothing (especially soles of the feet). Another case report demonstrates that even fatal lightning accidents are not always recognized correctly.     

指甲DNA的STR分型研究

目的 研究尸体所处环境、指甲DNA提取部位及提取方法对STR分型的影响。方法 对案件中不同条件腐败尸体指甲,使用不同部位、不同体系和时间消化,酚-氯仿法提取指甲核DNA,进行PCR扩增及STR分型。结果 提取指甲甲体、甲根部位均可获得STR分型。结论 指甲是法医检案中一类具有实用价值的检材。     

虹膜人工特征选择和标注方法的初步研究

目的本文主要研究基于虹膜图像的人工特征选择和标注方法,探寻虹膜人工鉴定研究方向,探讨虹膜技术作为一种新的刑事技术在诉讼中应用的可行性。方法首先,作者结合眼解剖学与虹膜基础理论,对虹膜特征进行了粗分类,分为五大类型:放射状沟线、向心沟、卷缩轮、隐窝和色素点;其次,作者结合已有的虹膜算法和图像处理方法对虹膜图像特征的提取和分析方法进行研究;最后,通过专用软件辅助,对虹膜图像进行区域切割、归一化、特征定位和标记、特征信息提取等系列处理。结果初步实现了两张虹膜图像在同一尺度下的人工特征选取和标注。结论本文研究的虹膜人工特征选择和标注方法,是虹膜识别技术在检验鉴定领域应用的初步探索,为后续虹膜人工比对鉴定的深入研究奠定基础。     

法医学DNA提取试剂盒优化及适用性评价

目的用磁性纳米磁珠和自主设计的试剂体系及提取流程,来建立一种基因组DNA的快速提取优化方案。方法利用自主研制的法医DNA提取纯化试剂盒设计实验方案对陈旧棉签血样进行DNA提取,用紫外分光光度计分析定量,通过对实验结果进行分析比较进一步优化自主研发的法医学DNA提取试剂盒。用优化之后的试剂盒提取各种不同的疑难捡材,探索本试剂盒的适用性。结果通过优化试验条件,同样获得了各种检材理想的DNA提取效果,却大大降低了DNA样本的提取成本。结论经优化过的国产磁珠DNA提取试剂盒完全可以应用与法医DNA检测中。     

免疫磁珠技术和精子抗原研究进展与法医学应用

免疫磁珠技术在生物学领域应用广泛,通过制备精子特异性抗体,并与磁性微球偶联,可达到对精阴混合斑中精子和女性阴道上皮细胞分离。本文简述了免疫磁珠技术的研究进展及磁珠主要制备方法,同时结合精子表面抗原的研究进展,提出磁珠抗体法提取精子DNA的可能性,并展望了磁珠抗体结合技术在法医学应用前景。     

On non-invasive 2D and 3D Chromatic White Light image sensors for age determination of latent fingerprints

The feasibility of 2D-intensity and 3D-topography images from a non-invasive Chromatic White Light (CWL) sensor for the age determination of latent fingerprints is investigated. The proposed method might provide the means to solve the so far unresolved issue of determining a fingerprints age in forensics. Conducting numerous experiments for an indoor crime scene using selected surfaces, different influences on the aging of fingerprints are investigated and the resulting aging variability is determined in terms of inter-person, intra-person, inter-finger and intra-finger variation. Main influence factors are shown to be the sweat composition, temperature, humidity, wind, UV-radiation, surface type, contamination of the finger with water-containing substances, resolution and measured area size, whereas contact time, contact pressure and smearing of the print seem to be of minor importance. Such influences lead to a certain experimental variability in inter-person and intra-person variation, which is higher than the inter-finger and intra-finger variation. Comparing the aging behavior of 17 different features using 1490 time series with a total of 41,520 fingerprint images, the great potential of the CWL technique in combination with the binary pixel feature from prior work is shown. Performing three different experiments for the classification of fingerprints into the two time classes [0, 5h] and [5, 24h], a maximum classification performance of 79.29% (kappa=0.46) is achieved for a general case, which is further improved for special cases. The statistical significance of the two best-performing features (both binary pixel versions based on 2D-intensity images) is manually shown and a feature fusion is performed, highlighting the strong dependency of the features on each other. It is concluded that such method might be combined with additional capturing devices, such as microscopes or spectroscopes, to a very promising age estimation scheme.     

Automated detection and classification of counterfeit banknotes using quantitative features captured by spectral-domain optical coherence tomography

Counterfeiting of banknotes is still a severe crime problem in many countries. One of the most significant issue for solving the crime is to classify the counterfeit types and identify the sources. Most of the current methods to classify counterfeit banknotes rely on manual examination that is time-consuming and labor-intensive. Moreover, these methods only detect surface features which can be easily imitated through advanced printing technology. In this study, an automated method based on optical coherence tomography (OCT) and machine-learning algorithms was proposed to classify different types of banknotes based on the internal features. A spectral-domain OCT (SD-OCT) system was employed for sub-surface imaging and quantitative assessment of banknotes. A total of 29 Chinese 100-Yuan banknotes were collected, in which 4 of them were real and 25 of them were counterfeiting by three different printing processes. Each banknote was imaged 10 times in 3 distinct regions, which resulted in a dataset of 290 samples. Each sample was characterized by extracting 2 A-scan (OCT signal intensity along depth) based features and 14B-scan (cross-sectional OCT images) based features. Several machine-learning models, including logistic regression (LR), support vector machines (SVM), K-nearest neighbor (KNN) and random forest (RF), were built and optimized as the classifiers that were trained using 203 samples and applied to predict 87 testing samples. The best performance was achieved by SVM classifier in which the sensitivity of 96.55% and specificity of 98.85% were obtained in discriminating between authentic and counterfeit banknotes, and the sensitivity of 94.67% and specificity of 98.22% were obtained in predicting the types of counterfeit banknotes. These classifiers were also evaluated using the receiver operating characteristic (ROC) curves. To the best of our knowledge, this is the first study where A-scan and B-scan derived features from OCT images have been used for the detection and classification of different types of counterfeit banknotes.     

Image matching algorithms for breech face marks and firing pins in a database of spent cartridge cases of firearms

On the market several systems exist for collecting spent ammunition data for forensic investigation. These databases store images of cartridge cases and the marks on them. Image matching is used to create hit lists that show which marks on a cartridge case are most similar to another cartridge case. The research in this paper is focused on the different methods of feature selection and pattern recognition that can be used for optimizing the results of image matching.The images are acquired by side light images for the breech face marks and by ring light for the firing pin impression. For these images a standard way of digitizing the images used. For the side light images and ring light images this means that the user has to position the cartridge case in the same position according to a protocol. The positioning is important for the sidelight, since the image that is obtained of a striation mark depends heavily on the angle of incidence of the light. In practice, it appears that the user positions the cartridge case with +/-10 degrees accuracy.We tested our algorithms using 49 cartridge cases of 19 different firearms, where the examiner determined that they were shot with the same firearm. For testing, these images were mixed with a database consisting of approximately 4900 images that were available from the Drugfire database of different calibers.In cases where the registration and the light conditions among those matching pairs was good, a simple computation of the standard deviation of the subtracted gray levels, delivered the best-matched images. For images that were rotated and shifted, we have implemented a "brute force" way of registration. The images are translated and rotated until the minimum of the standard deviation of the difference is found. This method did not result in all relevant matches in the top position. This is caused by the effect that shadows and highlights are compared in intensity. Since the angle of incidence of the light will give a different intensity profile, this method is not optimal.For this reason a preprocessing of the images was required. It appeared that the third scale of the "à trous" wavelet transform gives the best results in combination with brute force. Matching the contents of the images is less sensitive to the variation of the lighting.The problem with the brute force method is however that the time for calculation for 49 cartridge cases to compare between them, takes over 1 month of computing time on a Pentium II-computer with 333MHz. For this reason a faster approach is implemented: correlation in log polar coordinates. This gave similar results as the brute force calculation, however it was computed in 24h for a complete database with 4900 images.A fast pre-selection method based on signatures is carried out that is based on the Kanade Lucas Tomasi (KLT) equation. The positions of the points computed with this method are compared. In this way, 11 of the 49 images were in the top position in combination with the third scale of the à trous equation. It depends however on the light conditions and the prominence of the marks if correct matches are found in the top ranked position. All images were retrieved in the top 5% of the database. This method takes only a few minutes for the complete database if, and can be optimized for comparison in seconds if the location of points are stored in files.For further improvement, it is useful to have the refinement in which the user selects the areas that are relevant on the cartridge case for their marks. This is necessary if this cartridge case is damaged and other marks that are not from the firearm appear on it.     

Glass on clothing and shoes of members of the general population and people suspected of breaking crimes.

The outer clothing and footwear of 122 people attending a university gymnasium and a private gymnasium were searched for fragments of glass. Both the surfaces and the pockets of the clothing and the uppers and soles of the footwear were searched. New Zealand forensic glass cases have been reviewed to determine the amount of non-matching glass present on the clothing of people who are suspected of breaking crimes. Data from 114 suspects who had no matching glass on their clothing and shoes were accumulated. Statistical modelling techniques have been applied to the data collected.     

Forensic analysis of Telegram Messenger for Windows Phone

This article presents a forensic analysis methodology for obtaining the digital evidence generated by one of today's many instant messaging applications, namely “Telegram Messenger” for “Windows Phone”, paying particular attention to the digital forensic artifacts produced. The paper provides an overview of this forensic analysis, while focusing particularly on how the information is structured and the user, chat and conversation data generated by the application are organised, with the goal of extracting related data from the information. The application has several other features (e.g. games, bots, stickers) besides those of an instant messaging application (e.g. messages, images, videos, files). It is therefore necessary to decode and interpret the information, which may relate to criminal offences, and establish the relation of different types of user, chat and conversation.     

汗潜指印DNA提取方法的初步研究

目的建立渗透性载体及非渗透性载体上汗潜指印DNA的提取和检验方法。方法采用C-有-柱法及SiO2法两种DNA提取方法,PCR扩增后310型遗传分析仪检测。结果载玻片上3枚汗潜指印采用2种方法均可扩增出Amel及9个STR位点;纸上3枚汗潜指印用SiO2法检见Amel及9个STR位点,而用C-有-柱法检验结果不稳定。渗透性及非渗透性载体上1及2枚汗潜指印,采用上述两种DNA提取方法,检验结果均不稳定。结论所建立的方法可以检见渗透性及非渗透性载体上汗潜指印DNA,并达到同一认定的程度。     

Features of extracting phenol and 4-methylphenol from aqueous solutions

Phenol and 4-methylphenol were extracted from aqueous solutions by 5 organic solvents. The degree of extraction depended on such factors as type of extracting agent, pH of aqueous phase, and water saturation of extracting agent. The necessary number of extractions for obtaining the preset volumes of studied compounds is calculated.     

Extraction of nitrobenzene and its metabolite 3-aminohydroxybenzene from water solutions

The article presents the results of nitrobenzene and 3-aminohydroxibensene extraction from aqueous solutions by means of five organic solvents. The following factors influence on the extraction degree is shown: the nature of the extracting agent, aqueous phase pH, saturation of some extracting agents with water. The number of extractions for isolation of the necessary quantities of the compounds studied is calculated.