Reliability of paper brightness in authenticating documents

Evaluation of paper brightness in multipage documents is a practice of forensic document examiners when there is a question of a page insertion or substitution. This article demonstrates that occasional errors occur in the manufacturing process that affects the consistency of paper brightness. The inconsistency of paper brightness may therefore influence conclusions reached in authenticating documents. Reams of multipurpose paper, from 21 manufacturers, were examined. When assessing the individual pages of each package with an ultraviolet light, approximately 30% of the reams revealed differences in paper brightness. A study of the paper-manufacturing process was conducted to determine where variations originate. It is concluded that brightness differences occur when one incompatible roll of paper is mistakenly placed with others used for one production run. It was also determined that brightness variations (when present) are patterned throughout individual reams. When the authenticity of a document is in question, consideration of these findings is essential to assure an accurate assessment.     

Gelatine lifting, a novel technique for the examination of indented writing

The limitations of the examination of indented writing impressions using electrostatic detection are often paper related. Paper types such as glossy paper, paper of high basis weight, and lithography or gravure-printed papers often give rise to problems resulting in a decrease in sensitivity or a lack of detection altogether. In this paper, a novel technique for the examination of indented writing is presented, which is in a sense complimentary to the technique of electrostatic detection as it is especially suitable for glossy-coated and printed paper types and can in some instances also deal with paper types of higher basis weight. Indented writing grooves will normally contain more particles than the surrounding nonindented areas due to damage of the surface layer resulting in a build-up of filler powder. The method presented uses black gelatine lifter slabs to lift the paper dust image off the surface of the paper. This image can quite easily be photographed using near-to-coaxial lighting. The gelatine lifting method outperforms oblique lighting for the detection of indented writing and is almost as sensitive as electrostatic detection if compared on the types of paper where both perform well. The main advantage of this new technique is, however, that it is especially suitable for those types of paper where electrostatic detection fails and is therefore a welcome addition to the range of methods available to a forensic document examiner for the examination of indented writing.     

Enhancement of ninhydrin- or DFO-treated latent fingerprints on thermal paper

A new method for enhancement of ninhydrin or 1,8-diazafluoren-9-one (DFO)-treated latent fingerprints on thermal paper will be described. Most thermosensitive surfaces of thermal paper become dark when treated with DFO or ninhydrin petroleum ether (NPB) solution. This effect minimizes contrast between the developed fingerprints and the background. The new method described reduces this dark staining without removing the thermosensitive layer and parts of the developed fingerprints, as occurs with acetone washing. Through the new method, the developed fingerprints appear in sharp lines and high contrast. Extensive tests were performed, leading to an optimized working solution, which charges the paper with a minimum of chemicals, is cheap, and enables a large quantity of papers to be treated in a short time. The working solution contains commercially available, nonvolatile, nitrogenous organic compounds and can be used like the application of NPB solution by dipping.     

Evaluation of a Visualization Assay for Blood on Forensic Evidence

In forensics, bloodstains on dark fabrics might be invisible for the naked eye. Although several visualization, presumptive, and confirmatory blood tests have been developed, all have one or more disadvantages, especially on DNA analysis. We report here the use of a visualization assay that can visually detect blood drops up to 1/20 dilution. In this assay, the fabric is placed between two wet filter papers and covered by glass surfaces on both sides. Pressure is applied on the glass surfaces in which bloodstains transfer onto the filter papers through capillary forces. Detected stains can be tested with other more sensitive presumptive blood tests performed on the filter paper. Even more, DNA analysis can be performed on the transferred bloodstains. The presented visualization assay is easy to perform, extremely cheap, requires little hands on time, and does not affect bloodstain pattern analysis.     

两种方法提取汗潜手印DNA的比较研究

目的比较M48和DNeasy○R plant Mini两种方法提取汗潜手印DNA的优劣。方法用M48和DNeasy○Rplant Mini两种方法分别提取16对汗潜手印DNA,并进行DNA定量,比较定量结果。结果 M48法明显比plant Mini法提取到的DNA量多（配对t检验：α=0.05,t=3.45,γ=15,0.002     

4种固相颗粒吸附法提取滤纸血痕DNA效果的比较

目的探讨4种固相颗粒吸附法提取滤纸血痕样本DNA的效果。方法含有1μL静脉血的滤纸血痕180份,分为4组,每组45份。分别采用4种固相颗粒吸附法(DNAIQ~(TM)系统、D盾超敏DNA提取试剂盒、超高效硅珠纯化DNA提取试剂盒和常规的硅珠法)对上述样本进行DNA提取,对比各组DNA溶液的浓度及STR分型检验结果。结果 D盾超敏DNA提取试剂盒[(3.764±1.790)μg/mL]、超高效硅珠纯化DNA提取试剂盒(3.634±1.112)及常规硅珠法(3.350±1.250)提取到DNA溶液的浓度无统计学差异(P0.05),但均高于DNA IQ~(TM)系统(1.864±1.207)(P0.001);D盾超敏DNA提取试剂盒、超高效硅珠纯化DNA提取试剂盒及常规硅珠法样本图谱峰高大于DNA IQ~(TM)系统(P0.001),超高效硅珠纯化DNA提取试剂盒和常规硅珠法样本图谱峰高大于D盾超敏DNA提取试剂盒(P0.01)。结论 D盾超敏DNA提取试剂盒、超高效硅珠纯化DNA提取试剂盒及常规硅珠法对于滤纸血痕的DNA提取效率高于DNA IQ~(TM)系统;超高效硅珠纯化DNA提取试剂盒和常规硅珠提取到的DNA溶液可能具有更高的质量。     

法医毒物检验技术方法的质量要求

本文通过对73个法医毒物检验方法进行综合分析,从技术方法的质量特性上对方法的建立与确认提出质量要求.即从内部质量和外部质量的角度,针对法庭科学领域毒物检验技术方法,阐述其功能性、可靠性、易用性和有效性四个维度要求.     

Digital analysis of experimental human bitemarks: application of two new methods

Bitemark determination in forensic odontology is commonly performed by comparing the morphology of the dentition of the suspect with life-sized photographs of injury on the victim's skin using transparent overlays or computers. The purpose of this study is to investigate the suitability of two new different methods for identification of bitemarks by digital analysis. A sample of 50 volunteers was asked to make experimental bitemarks on the arms of each other. Stone study casts were prepared from upper and lower dental arches of each volunteer. The bitemarks and the study casts were photographed; the photos were entered into the computer and Adobe Photoshop software program was applied to analyze the results. Two methods (2D polyline and Painting) of identification were used. In the 2D polyline method, fixed points were chosen on the tips of the canines and a straight line was drawn between the two fixed points in the arch (intercanine line). Straight lines passing between the incisal edges of the incisors were drawn vertically on the intercanine line; the lines and angles created were calculated. In the painting method, identification was based on canine-to-canine distance, tooth width and the thickness, and rotational value of each tooth. The results showed that both methods were applicable. However, the 2D polyline method was more convenient to use and gave prompt computer-read results, whereas the painting method depended on the visual reading of the operator.     

Frequencies of morphological characteristics in two contemporary forensic collections: implications for identification

Positive identification relies on comparison of antemortem and postmortem data. Some identifications are based on morphological features such as fracture, pathological condition, and surgical hardware, despite little literature indicating the frequencies of such traits. This study examines whether such features are sufficiently rare as to be deemed individualizing. Data were collected on two modern North American skeletal collections (N=482 individuals). Presence/absence of features was scored by skeletal element and side. Results indicate that frequencies vary by geographic region (higher frequency of fractures and pathological conditions in New Mexico while individuals in Tennessee were more likely to have surgical interventions), many features such as fractures are remarkably common and that even suites of traits may not be individualizing. Caution is warranted when using written data rather than radiographic comparisons as the primary source of identification. The implications of these findings to missing person databases are also discussed.     

Evaluation of Purkait's triangle method for determining sexual dimorphism

The identification of sex from the skeleton is an important demographic assessment in medicolegal investigations. Rama Purkait developed a method for estimating sex using measurements from a triangle defined by three points on the proximal end of the femur using skeletal material from Bhopal, India. This method was tested with measurements on 200 Indo-European and African American adult femora from the Terry collection using discriminant function analysis to determine if Purkait's method was valuable for determining sex in Americans. A side-by-side analysis was conducted of Purkait's "triangle method" and the maximum diameter of the femoral head to determine their relative value in assessing sexual dimorphism. In the study sample a single variable from Purkait's method provided 85.5% prediction accuracy, similar to 87% for the head diameter. Combining threshold values for a single variable from Purkait's method and the femoral head diameter raised the predictability to greater than 90% for both sexes.     

Fluorescence Imaging of Posterior Spiracles from Second and Third Instars of Forensically Important Chrysomya rufifacies (Diptera: Calliphoridae),

Entomological protocols for aging blowfly (Diptera: Calliphoridae) larvae to estimate the time of colonization (TOC) are commonly used to assist in death investigations. While the methodologies for analyzing fly larvae differ, most rely on light microscopy, genetic analysis, or, more rarely, electron microscopy. This pilot study sought to improve resolution of larval stage in the forensically important blowfly Chrysomya rufifacies using high‐content fluorescence microscopy and biochemical measures of developmental marker proteins. We established fixation and mounting protocols, defined a set of measurable morphometric criteria and captured developmental transitions of 2nd instar to 3rd instar using both fluorescence microscopy and anti‐ecdysone receptor Western blot analysis. The data show that these instars can be distinguished on the basis of robust, nonbleaching, autofluorescence of larval posterior spiracles. High‐content imaging techniques using confocal microscopy, combined with morphometric and biochemical techniques, may therefore aid forensic entomologists in estimating TOC.     

Evaluation of two DNA/RNA co-extraction methods for body fluid identification in forensics

Body fluid identification has become a field of interest in forensic casework as it can add value to particular investigative scenarios. Identifying the source of the biological material is not always an upfront task using conventional methods; therefore, profiling of specific mRNA markers can provide the answer. The implementation of RNA based analyses in forensic casework must focus on the quality and sensitivity of methods, starting with nucleic acid extraction, and without loss of DNA for STR profiling. In this work, two methods for DNA and RNA co-extraction were tested and compared: a commercial kit that uses a spin, mini column methodology, and a quick, simple nucleic acid isopropanol precipitation based protocol. Both methods simultaneously extract DNA and RNA, crucial for forensic casework and were tested in semen samples. Nucleic acid quantifications as well as purity assessment ratios (OD₂₆₀/OD₂₃₀ and OD₂₆₀/OD₂₈₀) were obtained by both methods to infer on the use of extracts in downstream applications such as PCR. The performance of the two tested protocols was further evaluated by analyzing two semen mRNA specific markers, PRM1 and SEMG1. When compared to the commercially developed kit, results suggest that the literature adapted protocol allowed more carryover of contaminants absorbing at 230 nm and 280 nm as the purity ratios were below the accepted standard ranges. Negative results for mRNA profiling supported the QC results obtained by spectrophotometry. On the hand, PRM1 and SEGM1 were positive in RNA samples extracted with the commercial kit.     

The Use of an Alternate Light Source for Detecting Bones Underwater

When searching underwater crime scenes or disaster scenes for fragmentary human remains, it may be advantageous for forensic divers to be able to detect the presence of bones and teeth among other marine materials (such as shells and rocks). In terrestrial environments, this can typically be accomplished by visual and instrumental methods, but underwater conditions make it difficult to employ detection and sorting techniques in these environments. This study investigates fluorescence of bones and teeth and other marine materials using a submersible alternate light source (ALS) and concludes that an ALS can be a useful tool for detecting bones and teeth in underwater searches as well in terrestrial searches and laboratory environments. The results could impact the methods and equipment used by forensic divers and forensic anthropologists when searching for skeletal remains, potentially increasing the quantity and efficiency of forensic evidence recovered.     

Evaluation of match criteria used for the comparison of refractive index of glass fragments

For comparative glass examinations, the refractive indices (RIs) of recovered glass fragments are often compared to a test interval defined by measurements from a broken glass object. RI measurements from five modern float glasses were used via resampling to assess the frequencies of false exclusion errors for eight test criteria as functions of the number of measurements. The test criteria were based on ranges, fixed intervals, and multiples of standard deviations of the known source measurements. The observed error rates for the eight tests studied are between zero and c. 35%, depending upon the match criteria, the number of measurements, and the RI distribution for a glass source. The results of this study can be used to predict the false exclusion rate for a test criterion under a given set of conditions or to select test criteria that result in a desired error rate for these typical sheet glasses.     

Paths to destruction: the lives and crimes of two serial killers

Although research into the phenomenon of serial murder has revealed that serial killers frequently do not fit the initially described paradigm in terms of their physical and psychological profiles, backgrounds, and motives to kill, the media continues to sensationalize the figures of such killers and the investigators who attempt to analyze them on the basis of aspects of their crimes. Although the so-called "typical" profile of the serial murderer has proven accurate in some instances, in many other cases the demographics and behaviors of these killers have deviated widely from the generalized assumptions. This report details two unusual cases in which five and eight murders were committed in upstate New York. The lives and crimes of these offenders illustrate the wide spectrum of variations in the backgrounds, demographics, motivations, and actions witnessed among serial murderers, and highlight the limitations and dangers of profiling based on generalities.     

Effect of Heat on the Fluorescence Properties of Tooth‐Colored Restorative Materials and Their Forensic Implications

During antemortem and postmortem comparison of dental records of carbonized victims, restorations may be part of such records. The objective of this study was to evaluate the effect of heat on the fluorescence behavior of contemporary tooth‐colored restorative materials and natural tooth structure when subjected to range of temperatures, using illumination with 405 nm wavelength light. A total of 132 human extracted teeth restored with tooth‐colored restorative materials were exposed to heat (200, 500, 900, 1200°C) in an oven for 30 min. Samples were imaged before and after heat treatment. All tooth‐colored restorative materials underwent changes in color and in fluorescence properties, at each of the temperatures used. Resin‐based restorative materials still fluoresced at 200°C, and at 500°C underwent major color changes due to volatilization of resin. Materials containing inorganic fluorophores still fluoresced at 900°C, while at 1200°C, none of the materials tested in this study showed any fluorescence.     

Prediction of stature based on radiographic measurements of cadaver long bones: a study of the Croatian population

We tested a new approach to the stature prediction that could be used in the identification process of human skeletal remains of unknown identity. The stature of 19 female and 21 male adult cadavers was measured within 24 h after death and considered to be equal to the living stature. The antero-posterior radiographs of all limbs were taken, and the maximum length of the six long bones was measured from radiographs. There was a significant difference in the stature and maximum length of long bones between female and male cadavers (p<0.001 for all). The correlation between the stature and long bone length was the best for the humerus in females (r=0.792) and the tibia in males (r=0.891). Regression equations specific to the Croatian population were computed separately for each long bone in males and females and proven to be reliable in predicting the living stature of the individual.     

Identification of document paper using hybrid feature extraction

Document forgery is a significant issue in Korea, with around ten thousand cases reported every year. Analyzing paper plays a crucial role in examining questionable documents such as marketable securities and contracts, which can aid in solving criminal cases of document forgery. Paper analysis can also provide essential insights in other types of criminal cases, serving as an important clue for solving cases such as the source of a blackmail letter. The papermaking process generates distinct forming fabric marks and formations, which are critical features for paper classification. These characteristics are observable under transmitted light and are created by the forming fabric pattern and the distribution of pulp fibers, respectively. In this study, we propose a novel approach for paper identification based on hybrid features. This method combines texture features extracted from images converted using the gray-level co-occurrence matrix (GLCM) approach and a convolutional neural network (CNN), with another set of features extracted by the CNN using the same images as input. We applied the proposed method to classification tasks for seven major paper brands available in the Korean market, achieving an accuracy of 97.66%. The results confirm the applicability of this method for visually inspecting paper products and demonstrate its potential for assisting in solving criminal cases involving document forgery.     

Identification of Acer rubrum using amplified fragment length polymorphism

Amplified fragment length polymorphism (AFLP) analysis of botanical forensic evidence provides a means of obtaining a reproducible DNA profile in a relatively short period of time in species for which no sequence information is available. AFLP profiles were obtained for 40 Acer rubrum trees. Leaf material from five additional species was also typed. Genomic DNA was isolated using the DNeasy Plant Miniprep Kit (Qiagen, Valencia, CA), double-digested by two restriction endonucleases (EcoRI and MseI) and ligated to oligonucleotide adapters. Two consecutive PCR reactions (pre-amplification and selective amplification) were performed using a modification of the AFLP protocol described by Gibco (Invitrogen, Rockville, MD). The DNA fragments were separated by capillary electrophoresis using the CEQ 8000 DNA Fragment Analyzer. A number of Acer rubrum species-specific peaks were identified. In addition, within this closed set of samples, 15 of 16 (93.8%) blind samples were correctly identified. AFLP data can be used to determine the species of botanical evidence or to associate a sample to a source. This information can be used in forensic investigations to link a piece of evidence with a particular location or suspect.     

A comparative research of two lifting methods: electrostatic lifter and gelatin lifter

Two-dimensional dust shoeprints are often of very high resolution and contain unique features. Lifting these prints in the most effective method may contribute much to preserving these fine details. A research was conducted by experts from Israel and Switzerland to compare gelatin lifters and electrostatic lifters for lifting shoeprints. Several substrates were chosen, and on each material a set of dry dust shoeprints was made. A set of wet prints was made on paper as well. The shoeprints were approximately of the same quality, and the only variable was the nature of the material. On substrates indifferent to the method used, the preferable sequence was tested. Gelatin lifter was superior on most substrates and for wet prints. The superior sequence for using both methods is electrostatic lifting followed by gelatin lifter.