The probative character of Forensic Handwriting Examiners' identification and elimination opinions on questioned signatures

This 5-year study investigated the character of Forensic Handwriting Examiners' (FHEs) authorship opinions on questioned signatures through the medium of blind validation trials. Twenty-nine thousand eight hundred and eleven authorship opinions were expressed by FHEs on trial kits comprising randomized questioned genuine signatures (written by the specimen writer), disguised signatures (written by the specimen writer) and simulated signatures (not written by the specimen writer). Results showed that, as a group, FHEs were significantly more confident at identifying writers' genuine signatures than identifying writers' disguised signatures or eliminating specimen writers from having authored simulated signatures. It is proposed that the difference in FHE confidence arises from the difficulty they have in deciding which alternative authorship explanation accounts for perceived combinations of similar and dissimilar features between specimen and questioned signatures.     

The probative character of Forensic Handwriting Examiners’ identification and elimination opinions on questioned signatures

This 5-year study investigated the character of Forensic Handwriting Examiners’ (FHEs) authorship opinions on questioned signatures through the medium of blind validation trials. Twenty-nine thousand eight hundred and eleven authorship opinions were expressed by FHEs on trial kits comprising randomized questioned genuine signatures (written by the specimen writer), disguised signatures (written by the specimen writer) and simulated signatures (not written by the specimen writer). Results showed that, as a group, FHEs were significantly more confident at identifying writers’ genuine signatures than identifying writers’ disguised signatures or eliminating specimen writers from having authored simulated signatures. It is proposed that the difference in FHE confidence arises from the difficulty they have in deciding which alternative authorship explanation accounts for perceived combinations of similar and dissimilar features between specimen and questioned signatures.     

Are expert penmen better than lay people at producing simulations of a model signature?

Although forensic signature examination is considered to be an identification science, it is a theoretical possibility that an individual may learn to forge another person's signature that is free from indications of simulation behaviours. This proposition was tested in a signature blind trial that was administered to 42 forensic handwriting examiners (FHEs). Participants expressed opinions on the authorship of 100 questioned signatures. The questioned signatures comprised a mixture of genuine, disguised and simulated signatures. Calligraphers formed part of the population of individuals who provided simulated signatures for the trial. A total of 3100 opinions were expressed of which 1254 were correct, 224 misleading and 1622 were inconclusive. Of the opinions expressed regarding the simulated signatures, the misleading score for the calligraphers' forgeries were approximately four times that of the lay persons' forgeries. These results provide strong evidence in support of the proposition that calligraphers are more skilled at simulating signatures than are lay people and can produce forgeries that some FHEs have difficulty detecting.     

文件形成时间检验方法综述和评析

文件形成时间鉴定是判断文件真伪的重要途径。文件形成时间鉴定可通过三个技术通道来完成,即墨迹（包括印文印迹）的形成时间、纸制品的形成时间及文件内容的系统性分析。其中以墨迹的书写时间鉴定最为普遍。所以本文选取墨迹的形成时间鉴定技术作为评析重点,系统分析了半个多世纪以来涌现出来的众多墨迹形成时间鉴定的相关技术,并对其具体方法进行了归纳总结和简单的评析。本文在回顾历史、总结现在的基础上,提出了文件形成时间鉴定在未来发展的方向。     

Differentiation between inks of the same brand by infrared luminescence photography of their thin-layer chromatograms

A case is reported involving a U.S. Treasury check with an altered amount payable. The ink in the alteration and the ink in the endorsement signature were compared with ink from three Skilcraft ball pens all having Skilcraft black ink ball pen refills. Infrared luminescence photography of their thin-layer chromatograms revealed differences between the inks in the three pens.     

Investigating the effect photodegradation has on natural fibres at a microscopic level

It is a known fact that when fabric is left exposed to sunlight photodegradation occurs. However, no study has ever looked at the photodegradation that occurs to individual fibre filaments as commonly recovered from a scene of crime. To look at photodegradation of individual fibres, wool and cotton fabric were dyed using CI Acid Red 27 and CI Direct Red 80 respectively at two depths of shade, 0.25% and 2.0% owf. Pieces of fabric and individual fibre samples were then placed in a Light Fastness Q-Sun 1000 Xenon test chamber which simulated exposure to sunlight over two time periods, 64 h (equivalent to one weeks sun exposure) and 128 hrs (equivalent to two weeks sun exposure). The resulting pieces of fabric and fibres where then examined using high power comparison microscopy, as well as graded for colour fading using SDC Grey Scale for Assessing Change in Colour (including half steps). Results show that in both fibre types, photodegradation occurs in all samples, however, the degree of fading is shown to vary within a given fibre population showing it is unpredictable in nature.     

Evaluation of photometric stereo and elastomeric sensor imaging for the non-destructive 3D analysis of questioned documents – A pilot study

Photometric Stereo and Elastomeric Sensor Imaging were assessed for measuring the 3-dimensional (3D) morphology of questioned document samples. Photometric stereo is shown to be a powerful non-contact technique for revealing micron level detail of the samples examined. Elastomeric Sensor Imaging is shown to complement photometric stereo by yielding equivalent results. Additionally, this technique allows quantification of the morphological depth information. The techniques were applied to 2 different types of questioned document sample. Firstly, written signatures were examined. Both techniques were able to reveal characteristic features that could be used to infer stroke direction and ink line application sequence. Secondly toner/ink intersections were examined. Both techniques allowed visualisation of 3D features which were used to infer the sequence of application.     

Examination of a "velasco" signature on an oil painting

In September 2003, an investor bought an oil painting at auction in Denmark. The painting was signed "José Maria Velasco." The investor attempted to sell the painting in the United States, but found that he needed confirmation that this was an authentic Velasco painting. The provenance of the painting was questionable because it came to Europe from Cuba without appropriate documentation including the date of its entry into the European market. If the signature was determined to be authentic, the painting would have an approximate value of 1 million dollars. Initial research on the life and works of the artist and a literature review resulted in the preparation of an "Art Worksheet." Known signature specimens were obtained from reputable sources. A comparison of the known signatures with the questioned signature concluded the questioned signature was very probably not executed by José Maria Velasco.     

文件鉴定人员质量控制内容比较及启示

文件鉴定作为一项重要的司法鉴定活动,其鉴定意见作为证据被广泛地应用在诉讼阶段,同时,文件鉴定意见作为证据使用的风险也不容忽视。为了提供高质量的鉴定意见,文件鉴定专业的质量控制就显得尤为重要。特别是其学科较大地依赖于文件鉴定人的技术、经验、能力等背景,质量控制更应该侧重于对从业人员的质量管理。本文在调研国内外关于文件鉴定质量控制相关标准规范的基础上,在从业人员的资格审查、培训制度、考核制度等方面进行对比分析,从中发掘有益的启示,旨在为我国文件鉴定从业人员质量控制的建设和发展提供借鉴。     

The dynamic character of disguise behavior for text-based, mixed, and stylized signatures

The aims of this study were to determine if dynamic parameters (duration, size, velocity, jerk, and pen pressure) differed for signing style (text-based, stylized, and mixed) and if signing style influences handwriting dynamics equally across three signature conditions (genuine, disguised, and auto-simulation). Ninety writers provided 10 genuine signatures, five disguised signatures, and five auto-simulated signatures. All 1800 signatures were collected using a digitizing tablet resulting in a database of each signature's dynamic characteristics. With genuine signatures, there were significant differences between styles for size, velocity, and pen pressure, and there were significant differences between genuine signatures and at least one of the un-natural signature conditions for all parameters. For velocity and size, these changes with condition were dependent on style. Changes with condition for the other parameters were similar for the three styles. This study shows that there are differences among natural signature styles and disguise behaviors that may be relevant in forensic signature examinations.     

Passport examination by a confocal-type laser profile microscope

The author proposes a nondestructive and highly precise method of measuring the thickness of a film pasted on a passport using a confocal-type laser profile microscope. The effectiveness of this method in passport examination is demonstrated. A confocal-type laser profile microscope is used to create profiles of the film surface and film–paper interface; these profiles are used to calculate the film thickness by employing an algorithm developed by the author. The film thicknesses of the passport samples—35 genuine and 80 counterfeit Japanese passports—are measured nondestructively. The intra-sample standard deviation of the film thicknesses of the genuine and counterfeit Japanese passports was of the order of 1 μm The intersample standard deviations of the film thicknesses of passports forged using the same tools and techniques are expected to be of the order of 1 μm. The thickness values of the films on the machine-readable genuine passports ranged between 31.95 μm and 36.95 μm. The likelihood ratio of this method in the authentication of machine-readable Japanese genuine passports is 11.7. Therefore, this method is effective for the authentification of genuine passports. Since the distribution of the film thickness of all forged passports was considerably larger than the accuracy of this method, this method is considered effective also for revealing the relation among the forged passports and acquiring proof of the crime.     

谁是司法鉴定的“守门人”？——《关于司法鉴定管理问题的决定》实施五周年成效评析

本文从司法鉴定机构设置、司法鉴定活动启动以及司法鉴定意见审查三个方面论述了司法鉴定“守门人”问题。通过对两大法系国家各自司法鉴定制度的分析,梳理司法鉴定“守门人”的三道防线。同时有针对性地比较和讨论了我国司法鉴定制度缺陷,明确司法鉴定制度改革不能以牺牲鉴定意见“守门人”功能为代价。指出建立国家所属的具有公益性、中立性的司法鉴定机构是发展的必由之路。     

Sub-surface characterisation of latest-generation identification documents using optical coherence tomography

The identification of individuals, particularly at international border crossings, coupled with the evolving sophistication of identity documents are issues that authorities must contend with. Particularly, the ability to distinguish legitimate from counterfeit documents, with high throughput, sensitivity, and selectivity is an ever-evolving challenge.Over the last decade, an increasing number of security features have been introduced by authorities in identification documents. The latest generation of travel documents (such as passports and national ID cards) forego paper substrates for several layers of polycarbonate, allowing security features to be embedded within the documents. These security features may contain information at either the superficial and sub-surface levels, thus increasing the document’s resilience to counterfeiting.As the documents become harder to forge, so does the sophistication of forgery detection. There appears to be an unmet and evolving need to identify such sophisticated forgeries, in a non-destructive, high throughput manner.In this publication, we report on the application of optical coherence tomography (OCT) imaging on assessing security features in specimen passports and national ID cards. OCT allows sub-surface imaging of translucent structures, non-destructively enabling quantitative visualisation of embedded security features.     

Investigating forensic document examiners’ skill relating to opinions on photocopied signatures

Many forensic document examiners are hesitant to express authorship opinions on photocopied handwriting as the photocopying process results in less feature information than original writing. This study aimed to test the accuracy of 15 examiners' opinions regarding whether photocopied questioned signatures were genuine or simulated. Each examiner received the same set of original signature exemplars, from one individual, and a set of eighty questioned photocopied signatures comprising of genuine and simulated signatures. The overall misleading (error) rate for the grouped examiners' opinions was 0.9% providing strong evidence that examiners can make accurate observations regarding the authorship of non-original handwriting.