An examination of handwritten signatures forged using photosensitive signature stamp

Signature examination is the most common examination performed by any document examiner. Determination of the authenticity of a handwritten signature on a questioned document is an important task for forensic document examiners in the forensic science field. As a result of continuous developments in technology, a signature stamp can now be created using a photosensitive seal to enable the reproduction of a handwritten signature. These stamps are commonly used in China and several other countries. In this study, 10 types of black photosensitive stamp-pad ink, 10 brands of fountain pen ink, 15 types of black gel ink and six types of black erasable gel ink found on the Chinese domestic market were collected and 10 photosensitive signature stamps were created using the signatures of 10 people. Microscopic analysis, infrared (IR) and fluorescence analyses and microspectrophotometry (MSP) techniques were used to examine the resulting photosensitive signature stamp impressions when applied to printing papers, writing papers and invoice papers. By comparing the printing and spectral characteristics of the photosensitive signature stamp impressions with those of the signatures executed using the fountain pens, gel pens and erasable gel pens, it was possible to determine whether each signature was written or stamped using a photosensitive signature stamp. To validate these results, a 96.7% absolute accuracy and a 99.3% detection rate were achieved over a total of 150 blind tests conducted by five forensic document examiners, thus demonstrating that a combination of the four analysis methods used in this work can provide a more scientific approach and improve the accuracy and the detection rate of the examination process.

KEY POINTS

• A signature stamp is a photosensitive seal made in the style of a handwritten signature.
• Although microscopic analysis can usually provide better examination results, a comprehensive examination method that includes microscopic analysis and ink composition analysis is required to improve the accuracy and the detection rate of the examination process.
• This study collected and tested photosensitive stamp-pad inks, fountain pen inks, gel inks and erasable inks.
• Infrared and fluorescence analyses and microspectrophotometry were able to distinguish the photosensitive ink from both erasable ink and fountain pen ink.

Supplemental data for this article are available online at https://doi.org/10.1080/20961790.2021.1898755.     

Friction Marks of Stabbing Tools in Tires

When receiving a stabbed tire for examination, forensic toolmark examiners can determine whether a suspect tool was used in a specific crime based on class-characteristics and individual-characteristics marks that have been left by the tool on the tire. This study discusses friction marks and their forensic value during the examination of a punctured tire. The term friction mark refers to the noticeable mark around the penetration area on a tire's surface. Tires designed to create high friction when contacting a road. Due to this design, friction is created between the stabbing tool shank and the sides of the hole. As a result of this friction, the shank of the stabbing tool wears the outer layer of tire around the hole. This leaves a friction mark whose general shape reflects the cross-sectional shape of the stabbing tool’s shank. This phenomenon was observed and named by Locke (7) in his evaluation of tire puncture marks with knives. This article demonstrates the same phenomenon with other types of stabbing tools. Test stabs were produced with different tools representing a variety of cross-sectional shapes of shanks, and the resulting friction marks were photo-documented and discussed. Correlations between the various cross-sectional shapes and their corresponding friction marks are shown. Based on friction mark examination, the examiner: (i) can infer suspect tool shank cross-sectional shape with the evaluation of the friction mark shape and (ii) can deduce the maximum dimensions of the shank. This examination simplifies and accelerates the forensic comparison procedure and the investigation time.     

Reflectance Transformation Imaging (RTI) for the Documentation of Saw Mark Characteristics

Photography is widely accepted as a means of forensic case documentation and evaluation. In cases of criminal dismemberment digital microscopy is commonly used to assess marks left on the bone. Reflectance transformation imaging (RTI) is a computational photography technique which documents and enhances the three-dimensional (3D) reflectance properties of the surface of an object. RTI has primarily been used in the cultural heritage sector but has recently transitioned into forensic science. This study examines the use of RTI for the documentation and presentation of cut surface characteristics on fully sectioned long bones. Juvenile pig radii were bisected using three different handsaws, chosen as handsaws are the most common implement used in criminal dismemberments. The resulting 42 cut surfaces were then documented with a digital microscope and RTI. Four rendering modes were applied to the default RTI image, with diffuse gain being the most beneficial to accentuate cut surface features. Although great care must be taken when obtaining the photographic sequences necessary for detailed RTI analysis, RTI is relatively inexpensive, expeditious, and easy to use, and creates highly detailed, virtually interactive images. RTI may not replace microscopic methods of saw mark analysis, however could prove useful for the documentation, image sharing, and presentation of forensic evidence.     

影响犯罪现场足迹特征的因素

足迹在犯罪现场遗留是必然的,因此是现场中最常见的痕迹之一,它在刑事侦查中的作用也不言而喻。在足迹检验技术中,足迹检验的重点是对足迹各部位重压面的形态、特征进行检验,但足迹各重压面的形成又受诸多因素的影响,并且足迹形成后,与其他痕迹一样,其信息系统处于开放状态,也易受外界自然和人为等因素的影响。     

从剪切痕迹区别钢丝钳种类

对不同产地的八个品牌钢丝钳的外刃侧加工花纹特征及其在剪切痕迹中的反映作了研究.总结出了各品牌钢丝钳特征的差异,达到了区分的目的.为钢丝钳种类推断提供了一种确实可行的方法.     

Molecular study of time dependent changes in DNA stability in soil buried skeletal residues

Stamp marks are used as a unique identification for a range of items, but these can be erased for criminal activities. Erased marks can sometimes be recovered by etching or magnetic means. The present study looked at the application of Fry's reagent to recover erased marks from steel. The investigation also demonstrated that Fry's reagent can deteriorate on storing and will require a longer etching time. The effect of different applied forces of stamping was investigated, and the depth of the underlying deformation was determined by etching after varying degrees of metal removal. The amount of metal needing to be removed depends on the force applied to the die. Metal removal also affects the time needed for recovery. The underlying structural change remains as a hidden identification mark, and could potentially be used by manufacturers as an unseen identifier. A model for the underlying deformation is proposed.     

初谈船舶现场的勘验

论述了海事犯罪和海事事故调查中,船舶现场勘验的内容与方法,以期对涉及船舶的勘验工作起到一定的指导作用。     

钢丝表面线性痕迹的形成及检验

本文简要探讨了钢丝表面线性痕迹的形成机理、特定性、出现率以及相关痕迹的综合利用等问题.用案例说明钢丝表面线性痕迹检验鉴定的可行性和利用价值.     

浅议同一人穿不同鞋磨损特征的检验

在足迹检验鉴定中，同一人所穿的不同种类鞋子的鞋底磨损具有相同的特征，可以进行比对检验和同一认定。利用步法特征进行辅助检验时，步法特征的稳定性差、受外界因素影响大的特点要引起足够的重视。人负重状态下行走，鞋底会出现平时见不到的擦痕、迫痕及较深的压痕。如果行为人心理处于高度紧张状态，也会使其鞋印特征产生变异，所以比对检验时分析其行走过程是必不可少的内容之一。     

史学视野下的台湾知识产权法律保护

伴随经济、科技的发展，台湾地区市场经济机制逐渐趋于成熟，知识产权法律保护制度逐步建立和完善起来。台湾地区知识产权法律保护中的专利权、商标权和著作权法律保护是在原有法律制度基础上通过修改的方式逐步发展完善起来的。