GC Analysis of Black Gel Pen Ink Stored under Different Conditions

In many criminal and civil cases in China, the most commonly questioned documents are those written with gel pen ink. An important task for forensic document examiners is to identify whether two or more ink entries in one or more documents were written with the same ink type. The identification of the age of gel ink entries made poses an important and difficult problem for forensic document examiners. In this paper, the volatile components of gel ink were determined and the gel ink was classified by gas chromatography with a flame ionization detector. Calibration curves were created to express the relationship between the content of volatile gel ink components and the age of gel ink entries stored under natural and UV‐induced aging conditions. The correspondence between the natural and UV‐induced aging conditions was also established. The experimental results showed that GC was useful in the analysis of black gel ink and applicable for determining the relative age of gel ink entries under certain conditions.     

On the discriminability of the handwriting of twins

As handwriting is influenced by physiology, training, and other behavioral factors, a study of the handwriting of twins can shed light on the individuality of handwriting. This paper describes the methodology and results of such a study where handwriting samples of twins were compared by an automatic handwriting verification system. The results complement that of a previous study where a diverse population was used. The present study involves samples of 206 pairs of twins, where each sample consisted of a page of handwriting. The verification task was to determine whether two half-page documents (where the original samples were divided into upper and lower halves) were written by the same individual. For twins there were 1236 verification cases -- including 824 tests where the textual content of writing was different, and 412 tests where it was the same. An additional set of 1648 test cases were obtained from handwriting samples of nontwins (general population). To make the handwriting comparison, the system computed macro features (overall pictorial attributes), micro features (characteristics of individual letters), and style features (characteristics of whole-word shapes and letter pairs). Four testing scenarios were evaluated: twins and nontwins writing the same text and writing different texts. Results of the verification tests show that the handwriting of twins is less discriminable than that of nontwins: an overall error rate of 12.91% for twins and 3.7% for nontwins. Error rates with identical twins were higher than with fraternal twins. Error rates in all cases can be arbitrarily reduced by rejecting (not making a decision on) borderline cases. A level of confidence in the results obtained is given by the fact that system error rates are comparable to that of humans (lower than that of lay persons and higher than that of questioned document examiners [QDEs]).     

Simulation Detection in Handwritten Documents by Forensic Document Examiners

This study documents the results of a controlled experiment designed to quantify the abilities of forensic document examiners (FDEs) and laypersons to detect simulations in handwritten documents. Nineteen professional FDEs and 26 laypersons (typical of a jury pool) were asked to inspect test packages that contained six (6) known handwritten documents written by the same person and two (2) questioned handwritten documents. Each questioned document was either written by the person who wrote the known documents, or written by a different person who tried to simulate the writing of the person who wrote the known document. The error rates of the FDEs were smaller than those of the laypersons when detecting simulations in the questioned documents. Among other findings, the FDEs never labeled a questioned document that was written by the same person who wrote the known documents as “simulation.” There was a significant statistical difference between the responses of the FDEs and layperson for documents without simulations.     

Determination of the Chronological Order of a Laser Printing and Gel Pen Writing Without any Crossing Strokes

Laser printers and writing instruments are being exploited by the forgers to produce fabricated documents. They often produce such documents by appending genuine signature on a blank sheet and later printing on it. Often these fabricated documents do not contain intersection of strokes and may pose a difficulty to forensic document examiners in analyzing cases related to such documents. Keeping in mind the limited research work done on nonintersecting strokes, the present study has been conducted with an aim to determine the sequence of nonintersecting strokes of gel pens and laser printers. Three hundred samples of nonintersecting strokes of gel pen ink and laser printing were prepared. Of these 300, 150 had laser-printed text below the gel pen strokes and the remaining 150 were prepared with gel pen stokes below the laser-printed text. The samples have been analyzed using Nikon SMZ 800N stereomicroscope. Three micro-conformation features, that is, pattern of toner distribution, ink distribution, and fiber distribution have been observed in the samples. The results demonstrate the successful establishment of sequence of nonintersecting strokes in case of gel pen and laser-printed documents by the determination of micro-conformation features.     

Competency for Chinese Handwriting and Signature Examination

Chinese characters had their root some 4000 years ago and, with the growth in population, are used by over 1.3 billion people worldwide today; it is inevitable that document examiners would encounter cases involving the examination of Chinese handwriting regardless of their location. Although there are extensive studies on the examination of English handwriting in the literature, similar studies on Chinese handwriting are relatively limited. We are seeking to explore the obstacles and challenges for a document examiner who is unfamiliar with Chinese characters to apply the principles of identification and elimination of authorship described in the literature to examine Chinese handwriting, and how can these document examiners demonstrate their competency for conducting Chinese handwriting examination. This study provides a review of the literature, compares the methodology and key features in English and Chinese handwriting examination, and describes various workshops and proficiency testing programs organized to assist document examiners seeking development in Chinese handwriting and signature examination.     

Forensic Document Examiners’ Skill in Distinguishing Between Natural and Disguised Handwriting Behaviors

Abstract: Disguised handwriting is problematic for forensic document examiners (FDEs) and attracts higher misleading and inconclusive rates on authorship opinions than does genuine writing (Found B, Rogers D, International Graphonomics Society, 2005). There are currently no published empirical data on FDEs’ expertise in distinguishing between natural and disguised writing behavior. This paper reports on the skill of FDEs for determining the writing process of 140 pairs of natural and disguised writings and compares their results with those of a control group of laypeople. A significant difference was found between the examiner and lay group. FDEs’ expertise is characterized by their conservatism, where FDEs express a higher proportion of inconclusive opinions (23.1% for FDEs compared to 8.4% for the control group). This leads to the FDEs expressing a smaller percentage of misleading responses when calling writings as either naturally written or disguised (4.3% for FDEs compared with 12.2% for the control group).     

卧姿笔迹特征的实验研究

目的为卧姿笔迹鉴定提供识别和评断的参考依据。方法比较108个不同书写水平者的仰卧、左侧卧、右侧卧及俯卧笔迹与正常坐姿笔迹特征上的异同点,通过大量实验数据的统计分析,总结出卧姿笔迹特征及其变化规律,探讨可能的变化原因,并分析卧姿笔迹检验的要点。结果卧姿笔迹在字体、写法、错别字、笔顺、字间组合和单字的基本搭配比例等特征上较稳定。这些特征可作为本质特征使用。4种卧姿中,俯卧笔迹特征最稳定;书写水平高者笔迹特征也较稳定。结论卧姿笔迹鉴定应结合卧姿笔迹特征变化规律,准确判断笔迹的形成条件,去伪存真,做出科学的评断。     

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.     

Using automated comparisons to quantify handwriting individuality

The proposition that writing profiles are unique is considered a key premise underlying forensic handwriting comparisons. An empirical study cannot validate this proposition because of the impossibility of observing sample documents written by every individual. The goal of this paper is to illustrate what can be stated about the individuality of writing profiles using a database of handwriting samples and an automated comparison procedure. In this paper, we provide a strategy for bounding the probability of observing two writers with indistinguishable writing profiles (regardless of the comparison methodology used) with a random match probability that can be estimated statistically. We illustrate computation of this bound using a convenience sample of documents and an automated comparison procedure based on Pearson's chi-squared statistic applied to frequency distributions of letter shapes extracted from handwriting samples. We also show how this bound can be used when designing an empirical study of individuality.     

On the "general acceptance" of handwriting identification principles

Informed by the admissibility requirements of the broad and narrow Frye tests as well as Daubert's general acceptance factor, the present study elicited the views of a homogeneous group of forensic document examiners and a heterogeneous group of handwriting scientists regarding the degree to which a set of principles relating to the nature of handwriting and its identification were generally accepted within the respondents' fields. Among forensic document examiners, the greatest agreement was found concerning the process of examination, and somewhat less agreement on other matters. Forensic document examiners and handwriting scientists appear not to agree on the acceptability of most of the propositions.     

Kinematics of Signature Writing in Healthy Aging

Forensic document examiners (FDE) called upon to distinguish a genuine from a forged signature of an elderly person are often required to consider the question of age‐related deterioration and whether the available exemplars reliably capture the natural effects of aging of the original writer. An understanding of the statistical relationship between advanced age and handwriting movements can reduce the uncertainty that may exist in an examiner's approach to questioned signatures formed by elderly writers. The primary purpose of this study was to systematically examine age‐related changes in signature kinematics in healthy writers. Forty‐two healthy subjects between the ages of 60–91 years participated in this study. Signatures were recorded using a digitizing tablet, and commercial software was used to examine the temporal and spatial stroke kinematics and pen pressure. Results indicated that vertical stroke duration and dysfluency increased with age, whereas vertical stroke amplitude and velocity decreased with age. Pen pressure decreased with age. We found that a linear model characterized the best‐fit relationship between advanced age and handwriting movement parameters for signature formation. Male writers exhibited stronger age effects than female writers, especially for pen pressure and stroke dysfluency. The present study contributes to an understanding of how advanced age alters signature formation in otherwise healthy adults.     

基于银胶表面增强拉曼光谱检验蓝色书写字迹初探

目的用基于银胶的表面增强拉曼光谱技术检验蓝色签字笔字迹。方法取4种常见不同牌号的蓝色签字笔在其字迹上滴加微量银胶,用显微共焦拉曼光谱仪进行检验。结果不同品牌的蓝色签字笔字迹的表面增强拉曼光谱不同。结论基于银胶的表面增强拉曼光谱技术可用于纸张上蓝色签字笔字迹的检验。     

写字机器人伪造签名字迹的鉴别

目的通过实验研究使用写字机器人伪造的签名字迹特征,减小文件检验鉴定中的错判风险。方法以真实书写字迹为模板、使用市面上主流款式的写字机器人执不同种类书写笔进行书写,通过直接观察、显微观察、反射变换成像(RTI)方法观察等方式比对手写字迹和机器人书写字迹的差异,归纳写字机器人伪造字迹的主要特征,总结出有效的检验鉴别方法。结果通过研究发现写字机器人伪造签名笔迹的特点主要有起收笔为顿压笔,笔画出现细微的抖动歪曲现象,整体笔画笔压均匀,运笔生硬无笔势等。结论目前写字机器人伪造签名字迹与真实手写字迹还有一定差异,使用反射变换成像(RTI)方法观察能达到较好的检验效果。     

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。     

论笔迹鉴定结论的证据效力——兼谈“世纪遗产争夺案”的笔迹鉴定

笔迹鉴定在现代诉讼中日益增多,因其鉴定多依赖于＂经验知识＂,不具有可验证的重复性,也无法接受实证的重复性检验,致使其在作为证据使用时存在一定的分歧,尤其是遗嘱笔迹因书写人死亡,其鉴定结果更富有争议。香港历经＂八年＂旷日持久的＂世纪遗产争夺案＂中的笔迹鉴定颇具典型意义。笔迹鉴定结论如何在法庭中出示以及法庭对有争议的笔迹鉴定结论如何采纳或者排除,既是一个理论问题,又是一个制度问题,还是一个价值选择问题。因此,对笔迹鉴定结论的研究与探讨成为司法鉴定制度和证据制度必须直面的带有现实意义的问题。     

滚珠型签字笔笔痕特征的实验研究

目的归纳总结滚珠型签字笔笔痕特征的分类,为笔迹鉴定人正确使用此类笔迹特征提供科学的参考依据。方法本研究采用科学实验的方法,对20人使用不同品牌的三支签字笔书写的笔迹进行了观察与分析。结果同一人使用不同的签字笔、不同人使用同一支签字笔和不同人使用不同的签字笔书写所形成的笔痕现象具有相同的表现。结论签字笔笔痕特征只是众多笔迹特征当中的一种,不能单独依据此类特征出具鉴定结论。     

Individuality of handwriting

Motivated by several rulings in United States courts concerning expert testimony in general, and handwriting testimony in particular, we undertook a study to objectively validate the hypothesis that handwriting is individual. Handwriting samples of 1,500 individuals, representative of the U.S. population with respect to gender, age, ethnic groups, etc., were obtained. Analyzing differences in handwriting was done by using computer algorithms for extracting features from scanned images of handwriting. Attributes characteristic of the handwriting were obtained, e.g., line separation, slant, character shapes, etc. These attributes, which are a subset of attributes used by forensic document examiners (FDEs), were used to quantitatively establish individuality by using machine learning approaches. Using global attributes of handwriting and very few characters in the writing, the ability to determine the writer with a high degree of confidence was established. The work is a step towards providing scientific support for admitting handwriting evidence in court. The mathematical approach and the resulting software also have the promise of aiding the FDE.     

光谱成像检验同种同色涂抹掩盖字迹研究

目的建立一种无损、灵敏、直观的同种同色涂抹掩盖字迹的显现方法。方法依据涂抹掩盖字迹油墨物质的同色异谱特征,利用可见光滤波型多光谱成像检验系统进行检验。结果黑色圆珠笔、蓝色圆珠笔、黑色签字笔和蓝色签字笔相互涂抹掩盖形成的同种同色涂抹掩盖样本,利用可见光滤波型多光谱成像检验系统进行检验,显效率分别为90.5%、69.1%、49.5%、78.6%,显现效果良好。结论多光谱成像技术可以显现同种同色涂抹掩盖字迹,且具有良好的显现效果。     

一起故意伪装笔迹案件的检验与分析

本文就一起案件的检验,进一步强调我们鉴定人员,对笔迹检验特别是伪装笔迹的检验,笔迹特征的符合点、差异点的综合评断,需要分析犯罪嫌疑人主、客观各方面的原因,去伪存真,以作出正确的鉴定结论。     

Forensic investigation of OOXML format documents

MS Office documents could be illegally copied by offenders, and forensic investigators still face great difficulty in investigating and tracking the source of these illegal copies. This paper mainly proposes a forensic method based on the unique value of the revision identifier (RI) to determine the source of suspicious electronic documents. This method applies to electronic documents which use Office Open XML (OOXML) format, such as MS Office 2007, Mac Office 2008 and MS Office 2010. According to the uniqueness of the RI extracted from documents, forensic investigators can determine whether the suspicious document and another document are from the same source. Experiments demonstrate that, for a copy of an electronic document, even if all the original characters are deleted or formatted by attackers, forensic examiners can determine that the copy and the original document are from the same source through detecting the RI values. Additionally, the same holds true if attackers just copy some characters from the original document to a newly created document. As long as there is one character left whose original format has not been cleared, forensic examiners can determine that the two documents are from the same source using the same method. This paper also presents methods for OOXML format files to detect the time information and creator information, which can be used to determine who the real copyright holder is when a copyright dispute occurs.