Uncovering Forensic Evidence: A Path to Age Estimation through DNA Methylation

Age estimation is a critical aspect of reconstructing a biological profile in forensic sciences. Diverse biochemical processes have been studied in their correlation with age, and the results have driven DNA methylation to the forefront as a promising biomarker. DNA methylation, an epigenetic modification, has been extensively studied in recent years for developing age estimation models in criminalistics and forensic anthropology. Epigenetic clocks, which analyze DNA sites undergoing hypermethylation or hypomethylation as individuals age, have paved the way for improved prediction models. A wide range of biomarkers and methods for DNA methylation analysis have been proposed, achieving different accuracies across samples and cell types. This review extensively explores literature from the past 5 years, showing scientific efforts toward the ultimate goal: applying age prediction models to assist in human identification.

A Novel LIBS Sensor for Sample Examinations on a Crime Scene

In this work, we present a compact LIBS sensor developed for characterization of samples on a crime scene following requirements of law enforcement agencies involved in the project. The sensor operates both in a tabletop mode, for aside measurements of swabbed materials or taken fragments, and in handheld mode where the sensor head is pointed directly on targets at the scene. The sensor head is connected via an umbilical to an instrument box that could be battery-powered and contains also a color camera for sample visualization, illumination LEDs, and pointing system for placing the target in focus. Here we describe the sensor's architecture and functionalities, the optimization of the acquisition parameters, and the results of some LIBS measurements. On nano-plotted traces at silica wafer and in optimized conditions, for most of the elements the detection limits, in term of the absolute element masses, were found to be below 10 picograms. We also show results obtained on some representative materials, like fingerprints, swabbed soil and gunshot residue, varnishes on metal, and coated plastics. The last, solid samples were used to evaluate the depth profiling capabilities of the instrument, where the recognition of all four car paint layers was achieved.

Misinterpretation of a Gunshot Injury by a Non-forensic Medicine Expert: A Case Report of Misguidance in a Criminal Investigation Involving the Unusual Firearm Injury 'Kronlein Shot'

In India, the majority of postmortem examinations are conducted by medical professionals who lack expertise in the field of forensic medicine. Medicolegal autopsy services that are done by forensic experts are primarily confined to tertiary care centers, although a significant portion of medicolegal postmortem examinations occurs in non-tertiary healthcare setups. In this context, postmortem examination reports occasionally fail to encompass essential medicolegal features, resulting in dissatisfaction among both crime investigators and the deceased's relatives. As the doctors managing these postmortem examinations are not experts in the field of forensic medicine, if a case involves an unusual pattern of injury, the situation becomes further complicated. The absence of proper forensic assessments heightens the risk of the crime investigation heading in the wrong direction. Firearm injuries are well known for their varied pattern of injury. The present case reports one of the unusual patterns of firearm injury where a gunshot injury with close contact on the head resulted in the bursting of the skull, which is commonly referred to as a Kronlein shot. Such injuries involve extreme skull mutilation. Unlike typical contact gunshot injuries, in cases of extensive facial and cranial destruction, locating the entry wound and detecting other typical features of firearm injury become challenging. This complexity confused the autopsy surgeons of this case who were not experts in forensic medicine and mis-framed the opinion regarding the causative weapon which in turn confused the police official in the crime investigation. The case was later on referred to our institute for forensic medicine expert opinion and opinion was given after consideration of postmortem examination findings mentioned in the postmortem report, photographs of the deceased, circumstantial evidence gathered by police, and correlating all these facts with standard published literature. The case underscores the essential role of forensic experts in decoding complex medicolegal mysteries and ensuring accurate justice delivery. The case also highlights the importance of the need for comprehensive forensic examinations and considering circumstantial evidence in drawing various conclusions in a medicolegal autopsy.

Crime Light Imaging (CLI): A Novel Sensor for Stand-Off Detection and Localization of Forensic Traces

Stand-off detection of latent traces avoids the scene alteration that might occur during close inspection by handheld forensic lights. Here, we describe a novel sensor, named Crime Light Imaging (CLI), designed to perform high-resolution photography of targets at a distance of 2-10 m and to visualize some common latent traces. CLI is based on four high-power illumination LEDs and one color CMOS camera with a motorized objective plus frontal filters; the LEDs and camera could be synchronized to obtain short-exposure images weakly dependent on the ambient light. The sensor is integrated into a motorized platform, providing the target scanning and necessary information for 3D scene reconstruction. The whole system is portable and equipped with a user-friendly interface. The preliminary tests of CLI on fingerprints at distance of 7 m showed an excellent image resolution and drastic contrast enhancement under green LED light. At the same distance, a small (1 µL) blood droplet on black tissue was captured by CLI under NIR LED, while a trace from 15 µL semen on white cotton became visible under UV LED illumination. These results represent the first demonstration of true stand-off photography of latent traces, thus opening the way for a completely new approach in crime scene forensic examination.

Assessing the shooting distance of lead-free ammunition regardless of composition using Laser Induced Breakdown Spectroscopy

At present, it is challenging to accurately determine firearm shooting distances in the case that lead-free ammunition is involved, largely because different manufacturers use different primer compositions. Laser-induced breakdown spectroscopy (LIBS) allows the simultaneous detection of multiple elements with high sensitivity and so may represent a solution to this problem. Previous studies have, in fact, demonstrated that LIBS can be used to determine shooting distances when working with gunshot residues from conventional ammunition based on scanning fabric surfaces. The present study confirms that the shooting distance can be ascertained using LIBS to detect copper originating from the ammunition casing and projectile but not the primer on fabric surfaces. This estimation can be performed regardless of the primer composition of lead-free ammunition.

Key points

Evaluation of gunshot residue from lead-free ammunition using scanning electron microscopy-energy dispersive X-ray analysis indicated that 40% of the particles contained copper.The iForenLIBS system allowed the detection of copper-containing particles on fabric surfaces after firing at different distances with high sensitivity.Laser-induced breakdown spectroscopy can determine the shooting distance of lead-free ammunition through copper detection even in ammunition that does not used this element in the primer.This technique can generate density maps allowing the evaluation of short, medium, and long-range shooting distances.

A Summary of Concepts, Procedures and Techniques Used by Forensic Entomologists and Proxies

Forensic entomology is a branch of forensic science that incorporates insects as a part of solving crime. Insect-based evidence recovered at a crime scene can be used to estimate the minimum postmortem interval, determine if a carcass/corpse has been relocated, and contribute to the cause and manner of death. The current review summarises the stepwise usage of forensic entomology methods at a crime scene and in the laboratory, including specimen collection and rearing, identification, xenobiotic detection, documentation, and referencing previous research and casework. It also provides three standards for the collection of insects when attending a crime scene. The Gold standard attributes to a forensic entomologist (FE) who is likely to be well-trained attending a scene. The subsequent standards (Silver and Bronze) have been added because the authors believe that this information is currently missing in the literature. The purpose is so that an attending crime scene agent/proxy with some basic knowledge and some simple tools can recover almost all the insect information required by an FE to make the best estimation of the minimum postmortem interval.

Touch DNA Sampling Methods: Efficacy Evaluation and Systematic Review

Collection and interpretation of "touch DNA" from crime scenes represent crucial steps during criminal investigations, with clear consequences in courtrooms. Although the main aspects of this type of evidence have been extensively studied, some controversial issues remain. For instance, there is no conclusive evidence indicating which sampling method results in the highest rate of biological material recovery. Thus, this study aimed to describe the actual considerations on touch DNA and to compare three different sampling procedures, which were "single-swab", "double-swab", and "other methods" (i.e., cutting out, adhesive tape, FTA® paper scraping), based on the experimental results published in the recent literature. The data analysis performed shows the higher efficiency of the single-swab method in DNA recovery in a wide variety of experimental settings. On the contrary, the double-swab technique and other methods do not seem to improve recovery rates. Despite the apparent discrepancy with previous research, these results underline certain limitations inherent to the sampling procedures investigated. The application of this information to forensic investigations and laboratories could improve operative standard procedures and enhance this almost fundamental investigative tool's probative value.

Forensic applications of hyperspectral imaging technique: a narrative review

Hyperspectral imaging (HSI) collects and processes information from the entire electromagnetic spectrum to obtain the spectrum of each pixel in the image of a scene, with the aim of finding objects and identifying materials. It is a non-contact, non-destructive technology that can be used without modifying or altering the analysed target. Forensic analysis and crime scene investigations are two of the most investigated fields of application, being able to detect and analyse many types of evidence.In this paper we analysed the most commonly reported forensic science applications.The literature indicates that the fields in which HSI appears most promising are the analysis of blood traces, document forgery, gunshot residues and the identification of fingerprints.

Crime Scene Examination of a Suicidal Pact: A Case Report

A suicidal pact is a mutual agreement between two or more individuals to die together. In dyadic death, the assailant commits suicide soon after killing his victim. Cases of a suicidal pact and dyadic death are uncommon, especially in rural India. There are very few reported cases of suicidal pacts in the scientific literature. This present report highlights the death of three family members including a minor with the crime scene examination and challenges faced by the investigators and forensic experts. Being an expert in forensic medicine, we visited the crime scene and conducted post-mortem examinations to differentiate between suicidal pact and dyadic death.

Efficient DNA Sampling in Burglary Investigations

In terms of crime scene investigations by means of forensic DNA-analyses, burglaries are the number one mass crime in Switzerland. Around one third of the DNA trace profiles registered in the Swiss DNA database are related to burglaries. However, during the collection of potential DNA traces within someone’s residence after a burglary, it is not known whether the sampled DNA originated from the perpetrator or from an inhabitant of said home. Because of the high incidence of burglaries, crime scene investigators usually do not collect reference samples from all the residents for economical and administrative reasons. Therefore, the presumably high probability that a DNA profile belonging to a person authorized to be at the crime scene ends up being sent to a DNA database for comparison, has to be taken into account. To our knowledge, no investigation has been made to evaluate the percentage of these non-perpetrator profiles straying into DNA databases. To shed light on this question, we collected reference samples from residents who had been victims of recent burglaries in their private homes. By comparing the profiles established from these reference samples with the profiles generated from trace DNA, we can show that the majority of the DNA samples collected in burglary investigations belong to the residents. Despite the limited number of cases included in the study, presumably due to a crime decline caused by the pandemic, we further show that trace DNA collection in the vicinity of the break and entry area, in particular window and door glasses, is most promising for sampling perpetrator instead of inhabitant DNA.

Epigenetic Forensics for Suspect Identification and Age Prediction

Background: Genetic testing at crime scenes is an instrumental molecular technique to identify or eliminate suspects, as well as to overturn wrongful convictions. Yet, genotyping alone cannot reveal the age of a sample, which could help advance the utility of crime scene samples for suspect identification. The distribution of cytosine methylation within a DNA sample can be leveraged to determine the epigenetic age of someone's blood. Methodology: We sought to demonstrate the ability of DNA methylation markers to accurately discern the age of blood spots from an actual crime scene, a "mock" crime scene, and also from a tube of blood stored in ethylenediaminetetraacetic acid for >20 years. This was achieved by quantifying methylation within known age-associated genetic loci across each DNA sample. We observed a strong linear coefficient (0.91) and high overall correlation (R ² = 0.963) between the known age of a sample and the predicted age. Conclusion: We show that novel methods for targeted methylation and low-input whole-genome bisulfite sequencing can enable a novel and improved forensic profile of a crime scene that discerns not only who was present at the crime, but also their age. Finally, we use this model to discern the age and provenance of a blood sample that was used in a criminal investigation.

Traceology, criminalistics, and forensic science

There is a serious issue within the forensic science community, which even extends outside of the field. The role of the scientist in the investigation of crime has been increasingly confined to the laboratory, which has been accompanied by the conflation of the terms forensic science and criminalistics. This unfortunate situation has been festering for years. To make matters worse, the era of the proactive, problem-defining, criminalist (generalist) is waning, and possibly over. Present-day "criminalists" are treated as little more than reactive, protocol-constrained, laboratory technicians, with few, if any, consequential crime scene roles. In most cases, these "criminalists" merely respond to routine requests from prosecutors and police. The absence of science at the front end of forensic investigations, i.e., the scene, has resulted in biased, ineffective, inefficient, and/or erroneous outcomes with immediate and long-term societal impacts. To disentangle this imbroglio, we propose the use of another term, traceology, which has seen limited use worldwide except in the field of archaeology. With respect to criminalistics, this term has been previously proposed by Margot (20-21). Traceology is an historical science, dealing with the examination, analysis, and scientific interpretation of event traces (signs or remnants) of earlier activities. In this commentary, we define and redefine familiar, but ambiguous, terms and concepts with the hope of recapturing the essence of criminalistics (32), which we suggest is best termed traceology.

The specificity and reproducibility of general Schallamach pattern on heel part of rubber outsole

The Schallamach pattern is an acquired characteristic that is sometimes observed in crime scenes. However, the detailed pattern is not always visible, although its general pattern is still recognizable. To determine the discrimination power (DP) of the general Schallamach pattern (GSP), 55 outsoles worn by 33 volunteers were chosen for the experiment. Their prints were lifted after different intervals for six months using magnetic powder and self-adhesive lifters. After the prints were segmented into grids using Photoshop CS6, the presence/absence, angle, and density of the GSP were observed and measured in each grid. There were 18747 pairs of same-source samples among the 1447 dust impressions. An algorithm (weight combination of the presence/absence, angle, and density) was determined when a weight combination of the parameters considered recognized most of the same-source sample pairs. The results showed that the angles of the GSP on the left and right shoes were concentrated in the range [-5.5°, -20.43°] and [8.8°, 24.97°], respectively, and the DP was only 37.5%. With a simply optimized algorithm, the DP reached 54.82%, and the DP of sample pairs lifted within one day reached 79.04%. The study demonstrates that one can distinguish the Schallamach pattern on the heel part of the outsole without information regarding the presence/absence, angle, and density of patterns.

To Be There or Not to Be There, That Is the Question-On the Problem of Delayed Sampling of Entomological Evidence

Simple Summary

Proper evidence sampling is at the heart of a sound forensic opinion and failure to follow the standards and guidelines can have serious consequences for the report and expert testimony in court. In casework, forensic entomologists often must base their expert opinion on information about the case and insect evidence provided by third parties, and this presents pitfalls. We analyzed two of those: delayed evidence sampling and the effect of low-temperature storage of the body prior to the autopsy. Our study shows that sampling at the scene is advisable to facilitate a sound entomological report and that the cooling sequence of a corpse must be completely tracked between its removal from the scene until the insect sampling.

Abstract

The aim of the current study was to analyze two major pitfalls in forensic entomological casework: delayed evidence sampling and the effect of low-temperature storage of the body. For this purpose, temperature profiles of heavily infested corpses during cooling and cases in which insect evidence was collected both at the scene and during autopsy were evaluated with regard to species composition and development stages found. The results show that the temperature in the body bags remained at higher average temperatures up to 10 °C relative to the mortuary cooler, therefore, sufficient for larval development, with significant differences in temperature between larval aggregations on one and the same body. In addition, we found large differences both in species number, species composition, and the developmental stages found at the scene and during the autopsy. These data and observations underscore the importance of sampling evidence at the scene and recording temperatures throughout the cooling period of a body.

Improved Area of Origin Estimation for Bloodstain Pattern Analysis Using 3D Scanning

An important component of crime scene reconstruction is bloodstain pattern analysis (BPA). Where BPA concerns impact patterns, estimating the area of origin is critical information for scene reconstruction. Traditionally, this is achieved by measuring individual bloodstains and performing trigonometric calculations; however, 3D scanning has been proposed as a viable alternative for overcoming logistical and practical concerns with the manual method. Therefore, this project aimed to establish whether the FARO Focus 3D scanner and FARO Zone 3D software can improve the accuracy of area of origin estimates relative to the manual method. We created a series of eight bloodstain impact patterns and performed paired analysis using the two methods to estimate areas of origin for each pattern. Our data suggested that FARO-derived estimates were generally more accurate than using the manual method. FARO-estimated heights of origin areas were generally closer to the true distance. Both methods underestimated the distance from the wall for most patterns originating 150mm or greater from the wall, but overestimated distances for patterns originating closer to the wall. The degree to which distances were underestimated increased significantly the further the blood source was from the wall and was greater for FARO-derived estimates. The results of this research contribute to the validation of these instruments for operational implementation for BPA and should be considered alongside the practical benefits of 3D scanning relative to manual methods. Further, 3D scanning can provide reliable BPA reconstruction documentation for technical review and court presentation.

An Updated Sexual Homicide Crime Scene Rating Scale for Sexual Sadism (SADSEX-SH)

The Sexual Homicide Crime Scene Rating Scale for Sexual Sadism (SADSEX-SH) is a rating scale which dimensionally measures the degree of offender sexual sadism in suspected sexual homicide cases. Scoring is accomplished using crime scene and related investigative information. Preliminary norms for the SADSEX-SH prototype indicate that it correctly classified offenders with and without sexual sadism. This study further assessed SADSEX-SH sensitivity, specificity, and inter-rater reliability by comparing a larger sample of male sexual homicide offenders with (n = 20) and without (n = 20) sexual sadism. Two items generally undetectable at crime scenes were removed from the originally proposed 10-item scale, resulting in a final 8-item version. SADSEX-SH total scores for the two groups significantly differed (7.7 ± 3.5, range = 2-14 vs. 2.6 ± 2.0, range = 0-7, t = 5.58, p < .001). Inter-rater reliability was excellent (intraclass correlation coefficients [ICCs] = 0.6-1.0). Using a revised cutoff score of 6, sensitivity was 70.0% and specificity was 90%. This revised scale may prove useful for investigators, clinicians, and institutional professionals in helping to identify and address sexual sadism in sexual homicide offenders.

Evaluation of plant seed DNA and botanical evidence for potential forensic applications

Seeds, the reproductive organs of plants, are common as trace evidence from crime scenes. Seed evidence could be grouped into several categories based on the types of crimes they are associated with, including child abuse, homicides and drugs. Most commonly, seeds are examined microscopically and identified to the plant species level to show a linkage between persons and places. More recently, forensic researchers have evaluated the potential for extracting and typing DNA from seeds to further individualize the samples. As a model system, tomato seeds were examined microscopically after different cooking treatments and assessed for the potential to DNA type seeds for variety identification. A sufficient quantity and quality of DNA were recovered from uncooked, digested and undigested tomato seeds for amplified fragment length polymorphism (AFLP) analysis; however, any form of cooking destroyed the seed DNA. A simple microscopic analysis was able to distinguish between a cooked tomato seed versus an uncooked seed. This article is intended to provide an overview of case examples and current techniques for the forensic examination of seeds as plant-derived evidence.

The Use of Crime Scene and Demographic Information in the Identification of Non-Serial Sexual Homicide

As with other sexual offenders, sexual homicide perpetrators can be reluctant to talk about their criminal behavior. Therefore, in homicide cases, forensic practitioners frequently rely on crime scene information to identify any sexual behavior associated with the offense. This study aims to identify objective and readily available crime scene information, alongside information about victims and perpetrators, based on 65 cases from England and Wales in the United Kingdom of men convicted of homicide who had committed a non-serial sexual homicide and 64 cases of men convicted of homicide where the available evidence indicated that it was a non-serial non-sexual homicide. Chi-square tests and logistic regression were used to analyze the data. There were few differences in terms of demographic information and criminal histories between the two perpetrator groups. There were crime scene indicators supporting the use of Ressler et al.'s definition of sexual homicide. The victims of sexual homicide were generally found in their home with the lower half of the body exposed and with evidence of vaginal sex. Furthermore, extreme injuries and strangulation were more frequent in sexual homicides. Use of weapon was associated with a non-sexual homicide. Victims of sexual homicide were as likely to know the perpetrator as not. Potential benefits of the characteristics reported to investigators and forensic practitioners tasked with identifying sexual homicides are discussed and areas for further research suggested.

The Role of Forensic Botany in Solving a Case: Scientific Evidence on the Falsification of a Crime Scene

Forensic botany can provide useful information for pathologists, particularly on crime scene investigation. We report the case of a man who arrived at the hospital and died shortly afterward. The body showed widespread electrical lesions. The statements of his brother and wife about the incident aroused a large amount of suspicion in the investigators. A crime scene investigation was carried out, along with a botanical morphological survey on small vegetations found on the corpse. An autopsy was also performed. Botanical analysis showed some samples of Xanthium spinosum, thus leading to the discovery of the falsification of the crime scene although the location of the true crime scene remained a mystery. The botanical analysis, along with circumstantial data and autopsy findings, led to the discovery of the real crime scene and became crucial as part of the legal evidence regarding the falsity of the statements made to investigators.

[Nursing practice in the face of a potentially suspect situation]

Nurses are rarely confronted with potentially criminal situations in their professional practice. The nursing culture does not prepare them especially for such cases, nor for the actions to take to preserve a scene which may contain valuable clues in the event of any legal proceedings. Sometimes contradictory to nurses' reflexes when dealing with emergencies, some basic precautions are nevertheless essential.

The end of the (forensic science) world as we know it? The example of trace evidence

The dominant conception of forensic science as a patchwork of disciplines primarily assisting the criminal justice system (i.e. forensics) is in crisis or at least shows a series of anomalies and serious limitations. In recent years, symptoms of the crisis have been discussed in a number of reports by various commentators, without a doubt epitomized by the 2009 report by the US National Academies of Sciences (NAS 2009 Strengthening forensic science in the United States: a path forward). Although needed, but viewed as the solution to these drawbacks, the almost generalized adoption of stricter business models in forensic science casework compounded with ever-increasing normative and compliance processes not only place additional pressures on a discipline that already appears in difficulty, but also induce more fragmentation of the different forensic science tasks, a tenet many times denounced by the same NAS report and other similar reviews. One may ask whether these issues are not simply the result of an unfit paradigm. If this is the case, the current problems faced by forensic science may indicate future significant changes for the discipline. To facilitate broader discussion this presentation focuses on trace evidence, an area that is seminal to forensic science both for epistemological and historical reasons. There is, however, little doubt that this area is currently under siege worldwide. Current and future challenges faced by trace evidence are discussed along with some possible answers. The current situation ultimately presents some significant opportunities to re-invent not only trace evidence but also forensic science. Ultimately, a distinctive, more robust and more reliable science may emerge through rethinking the forensics paradigm built on specialisms, revisiting fundamental forensic science principles and adapting them to the twenty-first century.

A triple murder

Three partially burnt bodies were found in a burnt out bedroom. A candle and matches were found on a partially burnt bed, suggesting accidental deaths. Careful scene analysis and forensic post-mortems demonstrated that this was a multiple murder rather than an accident.

A Review of Forensic Science Management Literature

The science in forensic science has received increased scrutiny in recent years, but interest in how forensic science is managed is a relatively new line of research. This paper summarizes the literature in forensic science management generally from 2009 to 2013, with some recent additions, to provide an overview of the growth of topics, results, and improvements in the management of forensic services in the public and private sectors. This review covers only the last three years or so and a version of this paper was originally produced for the 2013 Interpol Forensic Science Managers Symposium and is available at interpol.int.

Application of Kinect gaming sensor in forensic science

Kinect sensor appears as a low-cost option for 3D modeling. This manuscript describes a methodology to test the applicability of Kinect to crime scenes. The methodology includes the comparison versus well-established scanners (Faro and Trimble). The parameters used for the comparison are the quality in the fitting of primitives, a qualitative evaluation of facial data, the data quality for different ranges, and the accuracy in the measurement of different lengths. The results show that the Kinect noise level increases with range, from 5 mm at 1.5 m range to 15 mm at 3 m range. It is considered that for detail measurements the sensor must be placed close to the target. A general measurement of a sample crime scene was analyzed. Errors in length measurements are between 2% and 10% for 3 m range. The measurement range must be limited to c. 3 m.

Infrared imaging of the crime scene: possibilities and pitfalls

All objects radiate infrared energy invisible to the human eye, which can be imaged by infrared cameras, visualizing differences in temperature and/or emissivity of objects. Infrared imaging is an emerging technique for forensic investigators. The rapid, nondestructive, and noncontact features of infrared imaging indicate its suitability for many forensic applications, ranging from the estimation of time of death to the detection of blood stains on dark backgrounds. This paper provides an overview of the principles and instrumentation involved in infrared imaging. Difficulties concerning the image interpretation due to different radiation sources and different emissivity values within a scene are addressed. Finally, reported forensic applications are reviewed and supported by practical illustrations. When introduced in forensic casework, infrared imaging can help investigators to detect, to visualize, and to identify useful evidence nondestructively.