Saw marks in bone: A preliminary empirical study to inform decision making and best practice.

Forensic toolmark examiners compare marks between those observed on an item/surface and those made by a reference implement, such as a particular tool or weapon, to provide an opinion of the likelihood of common origin. It is widely accepted that such comparison opinions need to be underpinned by empirical research, and this study aimed to add to the knowledge base relied upon when developing and comparing saw marks in bone, a substrate encountered in body dismemberment cases. Porcine bones were used as a human proxy; they were either fresh with residual soft tissue and bodily fluids present ('wet') to replicate dismembered bones shortly post-mortem, or processed to remove soft tissue and moisture content ('dry') to represent cases of dismemberment after an extended period of decomposition and exposure. The bones were cut using one implement of each of five classes: hand saw, mitre saw, reciprocating saw, oscillating saw, and serrated knife. They were cut, either completely through (except for serrated knife), giving two surfaces per cut to examine, or to a depth up to 3 mm (false starts). Five replicates per combination of bone condition, saw, and cut type gave 130 bone samples. These were then cleaned and cast using Isomark Silicone Polymer Compound or Mikrosil, giving 260 cast samples. All bone and cast samples were photographed, examined for various class characteristic markers, and specific markers measured. No significant differences between Isomark and Mikrosil casts were observed when compared side-by-side, demonstrating suitability of both materials for casting of saw marks on bone. Although saw marks presented more class characteristic markers on dry than wet bones, calculations of tooth distances and measurements of kerf width (KW) from marks did not significantly differ between bone conditions, with exception of the reciprocating saw that produced false start marks with significantly larger minimum KW on wet than dry samples. Further analysis supported that tooth distances on marks made by hand and oscillating saws are sufficiently accurate for the determination of saw teeth per inch (TPI). However, one tooth distance on marks made by reciprocating saws did not accurately represent TPI. Finally, examination of presence or absence of class characteristic markers on each saw mark demonstrated consistent variation between saw classes. These results enabled the development of exclusion-based decision trees, and a reference database (available on request), for use by toolmark examiners in their evaluation of saw types based on class characteristic markers observed in cut bone.

"Scalping" in the context of criminal dismemberment and mutilation-a case report and review of the literature.

We report on a case of criminal dismemberment and attempted scalping of a homicide victim with a "Mohawk" haircut. Case findings are presented. A review of the literature was performed for scalping in its historical and cultural context and particularly in criminal dismemberment and mutilation: Historically, scalping was prevalent in many ancient cultures around the world, where scalps were taken as trophies or "proof of kill", much like shrunken heads, trophy skulls, and other artefacts. Scalping was particularly widespread in Northern America in the context of tribal warfare, both before and after colonization. The iconic "Mohawk" haircut is closely linked with scalping, as it was meant to taunt the enemy. In the modern forensic context, scalping constitutes a form of criminal mutilation. However, cases of criminal dismemberment and mutilation are rare in forensic casework. Our literature review revealed a low number of scalping in criminal dismemberment and mutilation cases. The documentation was overall poor. Positioning scalping within the classification of criminal mutilation and dismemberment was difficult. In literature, even though case numbers were small, the majority of "textbook scalping" cases were German. The presented case, to our best knowledge, is the first modern-day photo-documented case of (attempted) scalping, even more so of a person wearing a "Mohawk".

Effects of a low-velocity fluvial environment on saw mark evidence in bone.

Saws are common tools used in postmortem dismemberment to alter human remains. Dismemberment may coincide with other concealment methods such as disposal in aquatic environments, so forensic anthropologists must recognize how taphonomy affects saw mark preservation. This study focuses on exposure of saw cut bone to a fluvial environment. Cross sections from pig humeri cut by a 7 TPI saw were evaluated on all cut surfaces for tooth hop (TH), exit chipping, and breakaway spurs. Pre-fluvial exposure, features were measured by two observers using a stereomicroscope while a one-dimensional profilometer was used to define surface roughness. Bones were randomly assigned to control or experimental groups and within each divided by duration of exposure (24, 48, 72, and 96 h). Control groups (four cross sections) were exposed to water in a 3-meter-long hydraulic channel; experimental groups (20 cross sections) were exposed to water and sediment in a 12-meter-long sediment-recirculating hydraulic channel. Velocity was maintained at 0.45 m/s. All measurements were repeated post-exposure. Observer A recorded 268 TH (mean: 3.70 ± 0.34 mm); post-exposure, count increased by 16.79% (mean: 3.71 ± 0.29 mm). Observer B recorded 247 TH (mean: 3.46 ± 0.42 mm); post-exposure, count decreased by 29.15% (mean: 3.36 ± 0.33 mm). All TPI estimates calculated include the 7 TPI saw. Exit chipping lost flakiness (in both channels), but was still visible. Breakaway spurs were not visibly altered. Surface staining was limited to bones exposed to sediment. Roughness was significantly lower in experimental groups post-fluvial exposure (W = 5705, p < 0.05). Overall, this fluvial environment did not obliterate saw mark evidence from bone.

Investigating error in saw mark minimum kerf width measurements.

Minimum kerf width (MKW) is often assessed in medicolegal cases of skeletal sharp force trauma and can provide information about the tool used. Previously published saw MKW research focuses on the relationship between MKW and saw blade set width (width of the saw blade including tooth set). Despite these publications using various measurement tools and methods to collect MKW, error in MKW measurements is not well-documented. The goal of this research was to investigate MKW measurement precision in terms of intraobserver error, interobserver error, and the effects of measurement modality (e.g., calipers versus stereo microscope). The study sample consisted of 351 incomplete cuts made with 27 diverse saws. MKW was collected using three methods: (1) inserting the internal caliper jaws into the incomplete kerf, (2) placing the external caliper jaws on the cortical surface, and (3) using a digital stereo microscope and associated measurement software. For each method, intraobserver error and interobserver error were assessed. Differences in measurements taken with the three measurement modalities were assessed for each observer as well. Relative technical error of measurement (rTEM) and coefficients of reliability indicate that internal caliper and stereo microscope measurements had the lowest intra- and interobserver error (rTEM = 3.72% to 6.15%; r = 0.98-0.996). External caliper measurements performed the worst (rTEM: intra = 8.53% and inter = 21.32%). There was higher precision between internal caliper and stereo microscope measurements than with the external caliper measurements. This research highlights the need for measurement standardization.

Criminal mutilation homicides in Japan: Corpse dismemberment and disposal pattern types, and offender characteristics.

This study examined the offender characteristics of criminal mutilation homicides in Japan for offender profiling. The current sample (N = 108) showed that the most typical offender was a male, in his 30s (age that observed most often), one-person, and acquainted with the victim. This study highlighted that the cases of mutilation homicide differed in comparison with the regular homicide group in terms of the victim-offender (VO) relationship and the number of offenders. Furthermore, the multiple correspondence analysis classified mutilation homicides into four behavioral pattern types based on two dimensions (level of "efforts of corpse dismemberment" and "efforts of corpse disposal"). In the first type "high evidence destruction effort (n = 29)", having the greatest efforts to destroy evidence, all offenders were men. The rates of no VO relationship and serial murders were higher. In the second type "convenient disposal (n = 32)", likely to abandon victim body in home and trash, the rate of female offenders who assaulted family members was statistically significantly higher among the four types. In the third type "high geographic distance (n = 23)", traveling long distances for corpse disposal, the percentage of cases by co-offenders was likely to be higher than in the other types. Lastly, the offenders in "low evidence destruction effort (n = 24)" were likely to kill other acquaintances and have the least efforts for corpse dismemberment and disposal. From these results, the criminal profilers can estimate mutilation homicide offenders on the basis of efforts of corpse dismemberment and disposal.

Advantages of micro-CT in the case of a complex dismemberment.

This case study reports the advantages of micro-CT to aid the investigative process in a complex dismemberment case. Micro-CT was successfully implemented to scan all skeletal remains of a dismembered female. The digital models were utilized to (i) screen for any further injuries not related to the dismemberment, (ii) provide measurements from false starts non-destructively, and (iii) visually represent the evidence in a structured format in court to improve the understanding of the forensic evidence by the jury. Acquiring high-resolution scans in this manner improved the efficiency of the forensic investigation by screening the remains and provided complementary toolmark evidence to the investigating team and forensic pathologist. A total of 14 false starts were identified along with the directionality of each dismemberment cut. Furthermore, the visual 3D representation of the remains in court provided a powerful tool to communicate this important evidence to the jury and form a prosecution narrative. As a forensic radiological method, micro-CT provided valuable information both in the investigation and the court presentation.

Tooth hop variability in human and nonhuman bone: Effect on the estimation of saw blade TPI.

Forensic research has demonstrated that tooth hop (TH) is a valuable measurement from saw-cut bones as it can be used to estimate teeth-per-inch (TPI) of a saw used in postmortem dismemberment cases. However, error rates for TPI estimation are still under development and knowledge of how bone tissue affects TH measurements remains unclear. The purpose of this research was to investigate the effects of tissue variability through the use of different taxa on the accuracy and precision of TH measurements in the bone to estimate TPI of the blade. A total of 1766 TH measurements were analyzed from human, pig, and deer long bones cut by two 7 TPI saw blades of different tooth type. Fifty distance-between-teeth measurements before and after sawing were collected directly from each blade for comparison to bone-measured TH to assess potential effects of tooth wear on TH variability. ANOVA and F tests were used to compare mean TH and variance, respectively, by saw-species (i.e., crosscut-deer, rip-deer) and species groups (i.e., all deer, all pig), with significance determined at the p < 0.05 level. TH measurements were converted to usable TPI ranges, which would typically be presented in a forensic report. It is concluded that significant differences in TH (mm) do not necessarily reflect significant differences in associated TPI ranges of suspect blades. Forensic reports should report mean TPI ± 1.5-2.5 TPI while providing a sample size indicating number of TH measured rather than just number of cuts or cut surfaces examined.

Dismembered porcine limbs as a proxy for postmortem muscle protein degradation.

The estimation of the postmortem interval (PMI) is of critical importance in forensic routine. The most frequently applied methods, however, are all restricted to specific time periods or must be excluded under certain circumstances. In the last years it has been shown that the analysis of muscle protein degradation has the potential to contribute to according delimitations in practice. In particular, upon biochemical analysis, the specific time points of degradation events provide reasonable markers for PMI delimitation. Nevertheless, considerable research is yet required to increase the understanding of protein decomposition and how it is affected by individual and environmental influencing factors. This is best investigated under standardized conditions, however, a considerate selection of proxies, regarding costs, effort, and expected outcome is required. Here, we use pigs to compare muscle protein decomposition in whole bodies and dismembered body parts (amputated hind limbs). Not only do experiments on body parts reduce the costs and allow easier handling in basic research, but also they aid to investigate the practical application of PMI estimation in dismembered body parts, or other extensive injuries, which are not unusual scenarios in crime investigation. Specifically, we investigated whether there are differences in the degradation rates of selected muscle proteins, sampled from dismembered legs and from hind limbs attached to whole pig bodies. Our results show distinct time-dependent degradation patterns of muscle proteins in a predictable manner regardless of sample origin. We are able to demonstrate that amputated hind limbs are suitable proxies for the analysis of muscle protein degradation, especially to investigate certain influencing factors and establish according standardized models.

The stereomicroscope and scanning electron microscope comparison of false starts bones produced by an oscillating autopsy saw.

In forensic anthropology, saw mark analysis plays an important role in cases of criminal dismemberment. Autopsy saw is not used by the perpetrator in cases of dismemberment, but the forensic pathologist may accidentally create false starts with this saw during an autopsy, especially while sampling bones for further analysis, and these autopsy false starts can be confused with false starts produced by the offender. In this study, the characteristics of 20 false starts were compared using stereomicroscopy (SM) and scanning electron microscopy (SEM). These bone false starts were selected at random from a previous study of 100 false starts created by an electrical oscillating autopsy saw on human femoral bones. That study had enabled the categorization of the lesions into two groups ("superficial group" and "deep group") with a 0.52 mm depth cut off, based on the dramatic differences in lesion characteristics between these two groups. In the current study, SEM confirmed the characteristics of the false starts (walls and profile shapes, striae, bone islands and bone debris were studied), and above all explained the mechanism whereby oval bone islands in deep lesions are formed. Bone islands are due to the horizontal and vertical movement of the oscillating autopsy blade.

Criminal mutilation in Sweden from 1991 to 2017.

We identified 43 cases of mutilation homicides in a nationwide population-based study in Sweden during the period of 1991-2017. 70% of cases were classified as defensive mutilations where the main motive was disposal of the body, while 30% were classified as offensive, that is, due to an expression of strong aggression, necro-/sexual sadism, or psychiatric illness. In comparison with a previous study covering mutilation homicides in Sweden between 1961 and 1990, we noted an increase in incidence. The percentage of cases involving mutilation had increased from 0.5% of all homicides in the 1960s to 2.4% in the 2010s. The most common cause of death was sharp force, but in 28% of the cases, the cause of death could not be determined. The clearance rate in cases of mutilation homicide was 67%, and in a large majority of the cases, the offender was known to the victim. With regards to gender women made up 44% of the victims, whilst men constituted 56% of the victims and a total of 95% of the offenders. Half of the offenders had a personality disorder, however, only 13% were sentenced to forensic psychiatric care.

Factores asociados a la identificación de cuerpos descuartizados o desmembrados en Medellín (Colombia) / Factors associated with the identification of dismembered bodies in Medellín, Colombia

OBJETIVO: Caracterizar los cuerpos desmembrados o descuartizados abordados en la Unidad Básica Medellín del Instituto Nacional de Medicina Legal y Ciencias Forenses (INMLCF) y establecer los factores asociados con su identificación. MATERIALES Y MÉTODOS: Estudio de corte transversal de registros de cuerpos descuartizados o desmembrados que ingresaron al INMLCF de Medellín entre los años 2013 y 2017. Para evaluar las variables asociadas a la identificación de los cadáveres descuartizados o desmembrados se aplicó el test estadístico de chi-cuadrado. RESULTADOS: En el periodo de estudio se encontraron un total de 54 cadáveres. Los factores asociados con la identificación de los cuerpos fueron cuerpos de personas mayores de 26años (OR: 1,22; IC95%: 1,04-1,43; p = 0,043) y los cuerpos encontrados en sitios únicos (OR: 1,22; IC95%: 1,04-1,43; p = 0,043). Los factores asociados con una mayor probabilidad de no lograr una identificación fueron ser hombre (OR: 1,14; IC95%: 1,02-1,27; p = 0,435) y los cuerpos descuartizados (OR 1,14; IC95%: 1,02-1,28; p = 0,354). DISCUSIÓN: La identificación de cuerpos descuartizados y desmembrados es un reto para el médico forense colombiano, pero conocer los factores asociados con su identificación favorece su adecuado abordaje, lo que mejoraría este proceso

OBJECTIVE: To characterise the dismembered bodies dealt with in the Medellín Basic Unit of the National Institute of Legal Medicine and Forensic Sciences (INMLCF) and establish the factors associated with their identification. MATERIALS AND METHODS: Cross-sectional study of records of dismembered bodies that entered the National Institute of Legal Medicine and Forensic Sciences of Medellin between 2013 and 2017. To evaluate the variables associated with the identification of dismembered bodies, using the chi-square statistical test. RESULTS: A total of 54 bodies were found during the study period. The factors associated with the identification of the bodies were bodies of people older than 26years (OR: 1.22; 95%CI: 1.04-1.43; P=.043) and bodies found in unique sites (OR: 1.22; 95%CI: 1.04-1.43; P=.043). The factors that were associated with a higher probability of not achieving identification were being male (OR: 1.14; 95%CI: 1.02-1.27; P=.435) and dismembered bodies (OR: 1.14; 95%CI: 1.02-1.28; P=.354). DISCUSSION: The identification of dismembered bodies is a challenge for the Colombian coroner, but knowing the factors associated with their identification enables an appropriate approach which would improve this process

Adult Dismembered Body With Myositis Ossificans: Evidence for Physical Abuse in an Autopsy Case Report.

ABSTRACT: A case involving an adult dismembered body with myositis ossificans (MO) is described. A woman in her 20s was found dead in her cohabitants' room. The body had dismembered into 15 pieces. Computed tomography showed ectopic mineralization in the bilateral upper arms and thighs. On autopsy, the skin and soft tissue were in the process of adipocere formation. Darkened areas that appeared to be subcutaneous hemorrhage were distributed on the face, left chest, and back. Bilateral upper arms and thighs showed organized granulations adherent to underlying bone. Microscopically, these organized lesions represented mature bone tissue in the periphery, cartilage tissue in the middle layer, and fibrotic tissue in the central part. These were typical findings of MO. Myositis ossificans and subcutaneous hemorrhage seemed to be evidence of antemortem repetitive physical abuse. In cases of dismemberment, the absence of organs and parts of the body provide limitations to determining cause of death. In forensic fields, adult autopsy cases involving MO are rare. This is an unusual case in which MO revealed antemortem physical abuse despite dismemberment of the body.

Through fire and flames: post-burning survival and detection of dismemberment-related toolmarks in cremated cadavers.

During a homicide investigation in which fire has been used to reduce the size of the cadaver and conceal the evidence of injuries, the identification of perimortem trauma presents a challenge, in particular in cases when the perpetrator has dismembered the body followed by burning the remains. It is therefore important to understand the effects which heat causes on fresh bone. The aim of this paper is to perform a pilot study on the survival ratio of toolmarks in different anatomical regions associated with dismemberment, and a descriptive analysis of the variables that may potentially influence the post-burning survival and detection. To achieve this, three donated embalmed cadavers were used to simulate a case in which an attempted dismemberment and burning had occurred. Fifty-five pre-burning injuries were manually induced: 30 using a machete to inflict chopping trauma, and 25 with a serrated bread knife to inflict sharp force trauma, on the thigh, knee, ankle and wrist. The cadavers were cremated in a furnace at Madrid's Cementerio Sur and the burnt remains were analysed at the Laboratorio de Antropología y Odontología Forense of the Universidad Complutense de Madrid. Not all pre-burning injuries inflicted were visible after the cremation process; only 13% were detected in this experiment. Toolmarks can be masked, modified, destroyed or overlooked from the outset of the procedure due to several factors which influence the post-burning survival and detection of toolmarks and contribute to conceal the evidence of trauma. Additional research should be done to study further variables which affect the post-burning visibility of sharp force trauma.

Correlation between saw blade width and kerf width.

Most studies of saw marks have focused on morphological characteristics and their utility in identifying saws suspected to have been utilized in cases of criminal dismemberment. The present study examined the extent to which metric analysis may be used to correlate saw blade measurements with minimum kerf widths (MKWs). A sample of 56 partially defleshed white-tailed deer (Odocoileus virginianus) long bones was utilized as proxy for human remains. The long bones were cut using a variety of commercially available saws, including 11 manual-powered and 5 mechanical-powered saws. A total of 496 false start kerfs (FSKs) were created. Two experiments were performed, with the first test examining the MKWs of FSKs produced on specimens that were restrained using a bench vise, while the second test analyzed the MKWs of FSKs produced on minimally restrained specimens. Statistical analysis using Hierarchical Linear Modeling (HLM) indicated a positive relationship between saw blade width (mm) and MKW, with blade width (p < 0.001) and the overall difference between the mechanical- and manual-powered saws (p = 0.029) tested, reaching statistical significance. A comparison of MKWs produced using manual-powered saws on restrained and minimally restrained bones suggests that restraint condition (p = 0.009) has a statistically significant effect. In comparisons of MKWs to blade widths, the average ratio for mechanical-powered saws is 18.7% greater than the average ratio for manual-powered saws. While the mode of the ratios was 1.42, thus supporting the general rule that MKW does not exceed 1.5 times blade width, multiple individual ratios did surpass 1.5.

Homicide and concealment of the corpse. Autopsy case series and review of the literature.

INTRODUCTION: The concealment of the body following a homicide undermines different moments of the forensic and medico-legal investigations. The aim of the present study is to provide an overview of the literature and the forensic casuistry of the Institute of Legal Medicine of Padova for analyzing and discussing diverse methodological approaches for the forensic pathologist dealing with covered-up homicides. MATERIAL AND METHODS: A literature review, updated until September 2019, was performed, and a literature pool of forensic cases was built. In-house cases were included by conducting a retrospective analysis of the forensic caseworks of Padova of the last 20 years. Data regarding epidemiology, methodology of assessment, methods of concealment, and answers to medico-legal issues were extracted for both data sets. RESULTS AND DISCUSSION: Seventy-eight papers were included in the literature review (78.2% being case reports or case series, 17% retrospective studies, and 6% experimental studies or reviews). Literature and in-house data sets consisted of 145 and 13 cases, respectively. Death scene investigation, radiology, toxicology, and additional analyses were performed in 20-54% of literature and 62-77% of in-house cases. Cover-up by multiple methods prevailed. Death was caused by head trauma in about 40% of cases (both data sets), strangulation in 21% of literature, and 7% of in-house cases, and was undetermined in 17% of literature and 7% of in-house cases. CONCLUSIONS: The methodology of ascertainment should be case-specific and based on a multidisciplinary and multimodal evaluation of all data, including those gained through novel radiological and/or analytical techniques.

Corpse dismemberment: A case series. Solving the puzzle through an integrated multidisciplinary approach.

The finding of corpse parts poses several challenges for the forensic pathologist presenting implications for identification, diagnosis of death and determination of wounds vitality. Further interpretative difficulties in cases of cadaveric dismemberment derive from the scarcity of tanatochronological parameters useful to estimate the post-mortem interval (PMI) and the absence of uniform investigative protocols in the different centres of forensic pathology. The present study proposes an investigation protocol for the cadaveric dismemberment through the discussion of a case series. The study group consisted of cases in which the dismemberment was performed after the murder. For all cases, a study protocol based on crime scene investigation, post-mortem computed tomography (PMCT), autopsy, toxicological, histological, immunohistochemical and genetic investigations was implemented. In particular, the standardised use of radiographic study before the autopsy allows all to have information that can guide the forensic pathologist during the autopsy. The use of immunohistochemistry allows an assessment of the vitality of the lesions possibly involved in the determinism of death, as well as of the surfaces of dismemberment, representing a tool of considerable utility for forensic purposes. The genetic investigations allow the identification of the victims, while the toxicological ones highlight the possible abuse of substances. The implemented protocol presents a demonstrated usefulness in improving diagnostic accuracy in corpse dismemberment cases.

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.

Dismemberment and Mutilation: A Data-Driven Exploration of Patterns, Motives, and Styles.

Classification of violent behavior, including dismemberment and mutilation, has become increasingly more significant. This study uses a data-driven classification system based upon knowledge drawn from the pertinent literature, and examination of cases of offenders who have dismembered or mutilated their victims. The latter were extracted from the Serial Killer Database, as well as media sources, and assessed for characteristics of the perpetrators and victim(s). An informational form was developed and used to establish quantitative parameters and objectively extract pertinent information that could be used for comparison and pattern analysis. Motives and styles, as well as the organized/disorganized dichotomy for murder and dismemberment/mutilation, were examined for each case. The majority of cases demonstrated defensive styles (60%), with the second most common being offensive styles (26%), which differs from previous studies that do not exclude older cases. Additionally, 68% of cases reflected organized patterns for both murder and the acts of dismemberment or mutilation. The results support a data-driven classification system that may serve as a foundational model for the investigation of specific motives of this type of deviant behavior in future research.

Analysis of false starts lesions on human bones produced by two hand saws with high TPI.

Cases of criminal dismemberment are encountered in forensic pathology and forensic anthropology. Saw mark analysis aims to determine the type of saw that was used: hand saw versus electrical saw, crosscut and universal saw versus rip saw, size of the teeth ("teeth per inch" TPI), and set type. The goal of this study was to analyze using a stereomicroscope a series of 60 experimental false starts (30 lesions for each saw) produced on human bones by two different handsaws with a high TPI (15 and 32). The lesions caused by these high TPI saws have rarely been described in the forensic literature. Saw 2 (rip hacksaw with a 32 TPI and a wavy set) displayed classical features. In contrast, saw 1 (universal panel saw, TPI 15, alternating set) did not produce the expected characteristics: the minimum width of the kerf was weak, the kerf walls were straight, the striae were straight, and the kerf profile was very peculiar with a succession of peaks and dips that has not yet been described.

Analysis of false start bone lesions produced by an electrical oscillating autopsy saw.

Postmortem dismemberment results from the use of sharp or sharp blunt instruments. Saws produce specific bone lesions, and the observation of certain saw mark features allows for the recognition of certain characteristics of the saw and its teeth. At autopsy, sections of the skull and other parts of the skeleton are usually achieved using an electrical oscillating autopsy saw. In cases of dismemberment, this autopsy saw may create additional marks to those produced by the criminal activity. In order to help the forensic pathologist to differentiate the two types of marks, this experimental study used a stereomicroscope to examine 130 experimental false starts produced on animal and human bones by an oscillating autopsy saw. A flagrant succession of narrow and wide aspects of the walls (in a "figure of 8" shape), with obvious oval bone islands and undulating striae are patterns typically left behind by oscillating autopsy saws, but the depth of the false starts plays an important role in the variation of the features. In particular, superficial false starts tend to be associated with larger kerf widths, straight walls, and longitudinal bone islands.