“印面凹凸痕特征”在原子印章鉴定中的价值

在原子印章鉴定中本文提出印文“印面凹凸痕特征”不受盖印压力影响,其特征反映价值高,较其它特征具有优越性,应予以重视.并且对“印面凹凸痕特征”的产生原因、分类、价值体现及注意事项做了分析说明.     

中国刑警学院法医系科研掠影

①张小东教授(右1)与课题组成员一起进行1997年部级项目《人体软组织损伤时间推断的研究》。②张振宇教授(前左3)向本科生介绍他的课题《印章色痕种属及其相对形成时间的理化鉴定方法研究》。③林子清教授(中)与青年教师一起研究由他主持的《中国五     

原子印章及其检验

原子印章印文特征(1)印文字体标准规范。主要是宋体、仿宋体个人印章有隶书体。(2)印文笔画、边框线条粗细,可有变化。因储墨垫具有一定弹性,捺印时压力大,印文线条粗,压力小,印文则细。(3)印文印色长期同质同色。(4)印文字间距离、角度等量。原子印章利用计算机制作章稿,因此字间距离、角度受计算机定格制约(除拼贴版)。(5)印文周围易出现印章托壳沾染印色残迹或压痕。因印章托壳内壁与储墨垫间隙很小,储墨垫上的印油很容易沾染到托壳上,捺印时托壳首先触及纸张为支撑,随即纸张也被托壳的沾染色沾染。用力大、衬垫物厚,易因压力作用留下压痕。(6)公章印文的星标中心部位无异迹。计算机制版克服了雕刻印章受雕刻材料及刀法工艺的限制所造成的螺纹及刀线留迹。(7)印文笔画间隙内不易被印油或灰尘粘堵。因原子印章印     

原子印章印文盖印相对时间的检验

近年来,随着原子印章的广泛应用,涉及原子章印文相对时间方面的检验案件越来越多,由于原子印章具有电脑制作、一次灌油多次使用等特点,检验难度较大,有相当一部分检验案件因受检验条件影响而     

Photoshop在原子印章印文检验中的运用

原子印章作为上个世纪80年代末出现的一种新型印章被广大客户接受并使用,但同时也为作案人伪造文件提供了方便,特别是在经济案件中,伪造印章印文的方式已从传统的手工雕刻发展到利用高科技伪造印章印文。本文作者结合案例,运用Photoshop图像处理软件对原子印章鉴别,在鉴别仿造的原子印章中发挥了技术优势作用。     

原子印章及其特征

本文初步探讨了原子印章的构成、生产工序特点及其印文特征,可供检验原子印章时参考。     

关于原子印章的检验

原子印章在我国始于70年代中期,其优点是便于保存,自身带印色,使用时可直接盖印在所需的文件上,且印文比一般的印章盖印的印文清晰,着色均匀,进行商贸活动时携带方便。在受理原子印章印文的检验中发现,如果采用常规的印章检验方法进行检验是不够完善的。因此,我们对原子印章的制作工艺流程进行了详细的调查研究,报告如下。     

紫外-可见光谱法研究蓝色圆珠笔色痕自然老化规律

目的论述自然老化下蓝色圆珠笔色痕中染料成分的变化规律。方法利用UV-VIS光谱对圆珠笔文字色痕中染料成分相对于铜酞菁的变化进行实验。结果得到染料与铜酞菁吸光度之比随老化时间变化的数据和曲线。结论利用UV-Vis光谱研究文件制成时间是可行的,为书写时间的鉴定拓展了思路。     

利用印章印文可变性印迹特征鉴别印文盖印时间

文件上印章印文可变性印迹特征通常表现为印文上的异物印迹,文字线条的断线、露白,印文边框的缺损,浓重的印泥(油)点或团块,以及原子印章的套框、支撑爪的印迹等。根据印章的印面结构和印面附着物的变化规律,通过被检验印文与该印章印文的历时样本的比较检验,以印文的可变性印迹特征的异同,推断被检验印文的盖印时间。1利用印面结构不可逆变化特征鉴别印文盖印时间印面结构的不可逆变化的特征,主要表现为印面结构的缺损、磨损特征。这类特征从无到有,由少到多,发展到不同的变化程度,标志印章印面的不同变化阶段。它的异同一般可以界定盖印的…     

签字笔墨水字迹形成时间研究综述

字迹色痕形成时间检验是法庭科学领域的热点和难点问题之一.签字笔现在已成为最常用的书写工具,签字笔墨水字迹形成时间鉴定成为字迹色痕形成时间鉴定技术的一个重要组成部分.文章对国内有关签字笔墨水字迹形成时间鉴定的文献进行了综述,介绍了用于形成时间鉴定的无损检验和有损检验方法,对各种方法的适用性和检验条件进行了简单的分析总结,以期对相关研究人员提供借鉴作用,并在各类案件的侦查、诉讼和审判中发挥作用.     

Identification and dating of the fountain pen ink entries on documents by ion-pairing high-performance liquid chromatography

A novel approach for the identification and dating of the fountain pen ink entries on paper has been established by ion-pairing high-performance liquid chromatography (IP-HPLC). Twelve black and six red fountain inks have been collected, and their ink entries have been prepared by drawing lines on paper. The chromatographic conditions for separation of their dye components after extraction with solvents were optimized. Under the optimized conditions, the 18 fountain pen inks were differentiated individually by comparing the number of detectable main or minor dye components, and the relative peak intensities of each component. The ink entries were artificially and naturally aged, and the analysis results showed that the ink dye components were significantly decomposed when exposed to UV or fluorescent light compare to those of inks stored under natural condition. The changes of the relative peak height for the dye components were linearly related to the aging time, especially under natural aging conditions. The degradation characteristics of the dye components under different aging conditions provide scientific evidences for dating of the suspicious fountain pen ink entries on document.     

应用HPLC研究蓝色签字笔迹字迹色痕光老化规律

目的对蓝色签字笔所形成的字迹色痕光老化规律进行研究。方法比对14种蓝色签字笔样品在暗处保存条件下、自然光照射及强灯光照射等老化条件下物理特征变化情况;使用高效液相色谱法,监测蓝色签字笔墨水中色料成分的变化情况,并寻找蓝色签字笔墨水字迹自然光老化规律。结果强灯光照射后出现外观明显的老化现象,暗处存放的样本存在较长的老化时限。在自然光照射下30天内,样品色料成分的相对含量均随时间发生两个阶段的变化。结论样本字迹的外观为鉴定蓝色签字笔墨水字迹的形成时间提供了重要的信息。结合HPLC分析结果,可以确认字迹是否经过光照人工老化,为字迹形成时间鉴定的重要参考依据。     

蓝色圆珠笔字迹色痕FT-IR光谱经时变化的研究

笔者曾用FT-IR光谱法对108种不同蓝色圆珠笔油墨进行了系统分析,确定了油墨组成成份,实现了种类认定.在此基础上,选取了二种不同种类的蓝色圆珠笔油墨字迹色痕,在紫外光下定时照射,根据各自光谱特征峰校正峰高的计算,确定相关峰的相对峰高比.根据相对峰高比值随时间变化的规律,进行了曲线拟合和计算机编程.同时,探讨了油墨组份之间随光照时间的变化,其目的是为了推断字迹色痕的“年龄”.     

Dating of Seals Produced with Stamp‐Pad Ink Using Gas Chromatography Method

Seals are often placed on important documents, and determining the date when a seal was affixed can be important to assess the authenticity of a document. In this study, thirty‐seven different brands of stamp‐pad inks and three different types of paper were used to make diachronic samples of the seals. The volatile components of stamp‐pad ink were determined, and the stamp‐pad ink was classified by gas chromatography with a flame ionization detector. Calibration curves were created to show the relationship between the content of volatile stamp‐pad ink components and the age of stamp‐pad ink entries stored under natural aging, UV‐induced aging, and heating aging conditions. The experimental results showed that GC was useful in the analysis of stamp‐pad ink and applicable for determining the relative age of stamp‐pad ink entries in some cases where the seal was placed on the document within 3 months.     

Raman spectroscopy of blue gel pen inks

Raman spectroscopy is becoming a tool of major importance in forensic science. It is a non-invasive, non-destructive analytical method allowing samples to be examined without any preparation. This paper demonstrates the use of the technique as a general tool for gel pen inks analysis. For this purpose, 55 blue gel pen inks, of different brands and models representative of gel pen available on the world market at the time of this study, were collected. A preliminary solubility test in methanol allowed separating them into two classes: 19 dye-based and 36 pigment-based gel inks. The latter were analysed by Raman spectroscopy (RS) using two wavelength laser sources (514.5 and 830 nm). Two main pigments were identified, pigment blue 15 and pigment violet 23.     

Identification of colorants in pigmented pen inks by laser desorption mass spectrometry

Pigments are rapidly replacing dyes as colorants in pen and printer inks, due to their superior colors and stability. Unfortunately, tools commonly used in questioned document examination for analyzing pen inks, such as TLC, cannot be used for the analysis of insoluble pigments on paper. Laser desorption mass spectrometry is demonstrated here as a tool for analyzing pigment-based pen inks. A pulsed nitrogen laser can be focused onto a pen stroke from a pigmented ink pen on paper, and positive and negative ions representative of the pigment can be generated for subsequent mass spectrometric analysis. Targeted pens for this work were a set of Uni-ball 207 pigmented ink pens containing blue, light blue, orange, green, violet, red, pink, and black inks. Copper phthalocyanine was identified as the pigment used to make both blue inks. A mixture of halogenated copper phthalocyanines were identified in the green ink. Unexpectedly, the pink ink was found to contain a red pigment, Pigment Red 12, treated with a mixture of water-soluble dyes. Each sample yielded ions representative of the pigments present.     

Age determination of ballpoint pen ink by thermal desorption and gas chromatography-mass spectrometry

Two main approaches can be used for determining the age of an ink: indirect dating and direct dating. Indirect dating is based on the chemical analysis of an ink followed by comparison with known samples in a reference collection. The collection should contain information about the inks including the market introduction dates. This approach may allow for an anachronism to be detected. The second concept is based on measuring ink components that change with age. The analysis of solvents in ballpoint inks may be a useful parameter for determining the age of ink on paper. In a previous study, the authors demonstrated that thermal desorption of ink directly from paper, followed by chemical analysis using gas chromatography-mass spectrometry (GC-MS), is a promising procedure for characterizing ink-binder resins and solvents. Preliminary tests showed that monitoring the evaporation of ink solvent from ink on paper is not a suitable method for ink dating. Thermal analysis of ink on paper in two steps revealed that fresh ink releases a relative amount of solvent at a certain low temperature in a defined period of time, which decreases as the ink ages. As a consequence, this relative amount of solvent released at a certain low temperature, and its decrease with time, can be used to estimate ink age. This age-dependent parameter was studied in 85 different inks ranging in age from 1 week to 1.5 years. It was found that some inks showed a significant decrease of this parameter up to an age of several months, and that the aging process can be monitored within this period. For other inks, however, the age-dependent parameter decreases relatively fast, e.g., within a few days, to a constant level, which can be too fast for casework. Based on these results, a general procedure for assessing the age of ballpoint pen inks on paper was developed.     

Comparison of natural and artificial aging of ballpoint inks

Abstract:  Solvent evaporation caused by aging from ballpoint inks was measured by gas chromatography/mass spectroscopy (GC/MS). The sample preparation was carried out with two different thermal desorption systems. The results are compared. Thirteen inks were classified with regard to their solvents, polymers, and additives. The variation of the aforementioned compounds caused by aging was monitored for naturally and artificially aged samples. In this paper, the results are compared and discussed with respect to forensic casework.     

Characterization of Printing Inks Using DART‐Q‐TOF‐MS and Attenuated Total Reflectance (ATR) FTIR

The rise in improved and widely accessible printing technology has resulted in an interest to develop rapid and minimally destructive chemical analytical techniques that can characterize printing inks for forensic document analysis. Chemical characterization of printing inks allows for both discrimination of inks originating from different sources and the association of inks originating from the same source. Direct analysis in real‐time mass spectrometry (DART‐MS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR) were used in tandem to analyze four different classes of printing inks: inkjets, toners, offset, and intaglio. A total of 319 samples or ~ 80 samples from each class were analyzed directly on a paper substrate using the two methods. DART‐MS was found to characterize the semi‐volatile polymeric vehicle components, while ATR‐FTIR provided chemical information associated with the bulk components of these inks. Complimentary data results in improved discrimination when both techniques are used in succession resulting in >96% discrimination for all toners, 95% for all inkjets, >92% for all offset, and >54% for all intaglio inks.     

Dating of Iron Gall Ink Using the Dissolution‐Diffusion Method

In many criminal and civil cases, some questioned documents are written with iron gall ink. Determining the date when an iron gall ink entry was written can be important to assess the authenticity of a document. A dissolution‐diffusion method was successfully employed to draw aging curves of iron gall ink entries stored in controlled conditions over 40 months. Calibration curves were created to indicate the relationship between the average dissolution‐diffusion rate of ink components and the age of ink entries stored under natural aging conditions. As preliminary findings of this study, the mixed solution of dimethyl formamide (DMF) and anhydrous ethanol was suitable to dissolve the dye of iron gall ink strokes made at different time. It was also determined that brands of iron gall inks, types of paper, and thickness of iron gall ink strokes had varying impacts on estimating the dates of iron gall ink strokes.