A Preliminary Assessment of the Identification of Saw Marks on Burned Bone*

Abstract: This study assesses the degree of modification to the saw mark characteristics of dismembered skeletal remains when exposed to a controlled outdoor fire of limited duration. The sample consists of 36 adult pig hind limbs which were dismembered fleshed. Six handsaws and six power saws were used, with three limbs dismembered and burned for each of the saw types. Results indicate that fire exposure affects the visibility and identifiability of saw mark striae. With the handsaws, the bow saw, hacksaw, and keyhole saw were consistently recognizable. In the power saw group, the saw marks of the jigsaw, reciprocating saw, and chainsaw remained identifiable. Although the bone ends exhibited thermal alterations, the false starts were well preserved with minimal damage. Given the parameters of this study, it is possible to identify the class of saw based on the diagnostic characteristics present on the cremated bones.     

Death by chainsaw: fatal kickback injuries to the neck

Each year over 3 million new chainsaws are sold in the United States. The operation of these newer saws combined with the millions of older chainsaws in circulation results in over 28,000 chainsaw-related injures annually. The majority of the injuries involve the hands and lower extremities with less than 10% involving injuries to the head and neck regions. Deaths while operating a chainsaw are extremely rare. The most common hazards associated with chainsaws are injuries caused by kickback, pushback, and pull-in. Kickback is the most common and poses the greatest hazard. Kickback occurs when the rotating chain is stopped suddenly by contact with a more solid area throwing the saw rapidly backward toward the operator. The cause of most injuries can be traced to improper use of the saw or poor judgment on part of the operator. We present two fatal chainsaw deaths; one with an older style saw, and the other with a modern type. In both cases the victims died from fatal injuries received to the neck region from a chainsaw kickback. The first case involved a 49-year-old white male operating an older style chainsaw with limited safety features. The second case involved a 38-year old white male who was operating a newer model chainsaw equipped with a low kickback chain in an unsafe manner.     

Suicide by a circular saw

The case of a suicide of a 32-year-old female using an electric circular saw is herein described. The decedent was suffering from depression and was found dead in her room. Beside her right hand was lying a circular saw, which was not running. The autopsy revealed a large gaping wound measuring 15.5 cm in length on the right side of her neck. The right external carotid artery, the right internal jugular vein, and the right internal carotid artery were cut and the injury reached to the cervical vertebra. Therefore, the cause of death was exsanguination. An individual who commits suicide with an electric saw, such as a chain saw, band saw, and circular saw is rare; in particular females rarely select this method as the means of suicide. However, we herein report the case of a female patient with a psychiatric disease who successfully committed suicide with a circular saw.     

Unusual suicides of young women with tentative cuts and fatal neck injuries by chain saw and circular saw

Suicides with chain saws and circular saws are extreme exceptions, in particular with regard to females and concerning the neck region. We report two of such rare cases involving young women. A 30-year-old female with a known schizoaffective psychosis killed herself with an electric chain saw. The autopsy revealed a deep saw cut of the neck and shoulder with partial transection of the cervical spine. Several tentative saw cuts were present on the right lower jaw. A 29-year-old woman suffering from depression committed suicide by use of a circular saw. She inflicted herself fatal neck injuries with at least three separate cutting procedures. Our cases were characterized by the following features: female sex, young adulthood, no occupational experience with saws, psychiatric disorders, absence of alcohol or drugs, use of an aggressive method of suicide, focus of saw injuries on the right side of the neck, detection of tentative saw cuts or several trials, identical causes of death (exsanguination and blood aspiration).     

Recovery of human remains after shark attack

Two cases of fatal shark attack are reported where the only tissues recovered were fragments of lung. Case 1: An 18-year-old male who was in the sea behind a boat was observed by friends to be taken by a great white shark (Carcharodon carcharias). The shark dragged him under the water and then, with a second shark, dismembered the body. Witnesses noted a large amount of blood and unrecognizable body parts coming to the surface. The only tissues recovered despite an intensive beach and sea search were 2 fragments of lung. Case 2: A 19-year-old male was attacked by a great white shark while diving. A witness saw the shark swim away with the victim's body in its mouth. Again, despite intensive beach and sea searches, the only tissue recovered was a single piece of lung, along with pieces of wetsuit and diving equipment. These cases indicate that the only tissue to escape being consumed or lost in fatal shark attacks, where there is a significant attack with dismemberment and disruption of the integrity of the body, may be lung. The buoyancy of aerated pulmonary tissue ensures that it rises quickly to the surface, where it may be recovered by searchers soon after the attack. Aeration of the lung would be in keeping with death from trauma rather than from drowning and may be a useful marker in unwitnessed deaths to separate ante- from postmortem injury, using only relatively small amounts of tissues. Early organ recovery enhances the identification of human tissues as the extent of morphologic alterations by putrefactive processes and sea scavengers will have been minimized. DNA testing is also possible on such recovered fragments, enabling confirmation of the identity of the victim.     

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.     

Soft Tissue Decomposition of Submerged,Dismembered Pig Limbs Enclosed in Plastic Bags*

Abstract: This study examines underwater soft tissue decomposition of dismembered pig limbs deposited in polyethylene plastic bags. The research evaluates the level of influence that disposal method has on underwater decomposition processes and details observations specific to this scenario. To our knowledge, no other study has yet investigated decomposing, dismembered, and enclosed remains in water environments. The total sample size consisted of 120 dismembered pig limbs, divided into a subsample of 30 pig limbs per recovery period (34 and 71 days) for each treatment. The two treatments simulated non‐enclosed and plastic enclosed disposal methods in a water context. The remains were completely submerged in Lake Ontario for 34 and 71 days. In both recovery periods, the non‐enclosed samples lost soft tissue to a significantly greater extent than their plastic enclosed counterparts. Disposal of remains in plastic bags therefore results in preservation, most likely caused by bacterial inhibition and reduced oxygen levels.     

Fatal and Nonfatal Rip Saw Injuries

This paper deals with a fatal stab wound suffered by a 29-year-old man and nonfatal injuries of 35-year-old and 67-year-old saw operators. Rip saw is a machine that is specially designed for making a rip cut, a cut made parallel to the direction of the wood grain. Rip-saw-related injuries mostly occur when a person is struck by the cutting material, which usually involves splinters of irregular shape and diameter. When the splinter strikes the body diagonally, the injuries may include abrasions, lacerations, and cut wounds; in situations where the victim is struck directly, the most common injuries are oval- or star-shaped stab wounds with a varying width of abrasions around the wounds. Therefore, such injuries may come across as injuries produced by a knife-like instrument, which is an added difficulty in the interpretation of such injuries.     

Unusual suicide with a chainsaw

Described here is a case of suicide with the use of a chainsaw. A female suffering from schizophrenia committed suicide by an ingenious use of a chainsaw that resulted in the transection of her cervical spine and spinal cord. The findings of the resulting investigation are described and the mechanism of suicides with the use of a chainsaw is reviewed. A dry bone study was realized to determine the bone sections, the correlation between anatomic lesions and characteristics of chainsaw. The damage of organs and soft tissues is compared according to the kinds of chainsaw used.     

Deep incisional neck injuries caused by an electric knife

Electric knives, due to the double blades swinging in opposite directions, have a high injury potential. Tissues such as skin can be cut smoothly without cutting motion and with only little pressure. Authors report on the case of a woman of 47 years who cut herself deeply on both sides of her neck with an electric knife, slightly carving a notch into the larynx and a cervical vertebra and opening large blood vessels. With respect to the extent of injuries the capacity to act had to be questioned. However, considering the absence of venous air embolism and the peculiarity of the tool it had to be assumed that the capacity to act lasted for a short time.     

Impact Spatter Bloodstain Patterns on Textiles

There are few reports of studies of impact spatter on textiles even though bloodstained textiles are found at many violent scenes. Impact spatter was deposited at 90° impact angle onto three knit fabrics of different yarn sizes and on paper. The resulting stain areas and number of stains were measured using ImageJ and compared with stains on paper using one‐factor ANOVA. The number of stains observed and their areas on the knit fabrics decreased as the yarn size increased. It was also found that blood that deposited on the fabric wicked only in the direction of the fibers at that location within the fabric which led to distorted stain shapes. Fewer observed impact spatter stains were found on cotton jersey knits for fabrics made with larger yarns than on paper. As the yarn size became smaller, the number of stains became the same as on paper.     

Vacuum metal deposition: visualisation of gold agglomerates using TEM imaging

Vacuum metal deposition (VMD) is a well-established technique that can be used for the development of latent fingermarks on a range of polymer surfaces, including polyethylene (PE) bags exposed to harsh environmental conditions. The technique has also proved to be effective on difficult semi-porous surfaces such as the polymer banknotes in circulation in Australia and in an increasing number of other countries. VMD is a two-stage technique. In the first stage, a small amount of gold is deposited under high vacuum onto the exhibit. This is then followed by the deposition, onto the gold layer, of a much thicker layer of zinc. Normal VMD development is characterised by zinc depositing all over the surface except on the fingermark ridges themselves. A phenomenon of reverse development (zinc on the ridges but not on the surface) has been reported by many authors. Recent studies indicated that this phenomenon might occur on low-density polyethylene (LDPE) when the amount of deposited gold is above an optimum quantity. The results suggested that the size of the gold agglomerates formed on the surface of the polymer plays a critical role. This preliminary study was aimed at visualising, by transmission electron microscopy (TEM), the formation of gold agglomerates on polymer surfaces to gain an appreciation of how the density and size of these agglomerates changes with an increasing amount of evaporated gold.     

Feasibility of Contactless 3D Optical Measurement for the Analysis of Bone and Soft Tissue Lesions: New Technologies and Perspectives in Forensic Sciences

Abstract:  In forensic pathology and anthropology, a correct analysis of lesions on soft tissues and bones is of the utmost importance, in order to verify the cause and manner of death. Photographs, videos, and photogrammetry may be an optimal manner of immortalizing a lesion, both on cadavers and skeletal remains; however, none of these can supply a detailed three-dimensional (3D) modeling of the lesion. Up to now, only the use of casts has given us the possibility of studying deep lesions such as saw marks with an accurate and complete 3D reconstruction of bone structure. The present study aims at verifying the applicability of 3D optical contactless measurement for the accurate recording of soft tissue and bone lesions, in order to develop a unique and precise method of registering and analyzing lesions, both in forensic pathology and anthropology. Three cases were analyzed: the first, a car accident with blunt force skin injuries; the second, a murder with blunt force injury to the head applied with a metal rod; the third, a series of sharp force knife and saw lesions on bone. Results confirm that 3D optical digitizing technology is a crucial tool in the immortalization of wound morphology in the medico-legal context even on "difficult" substrates such as cut marks and saw marks on bone.     

Detection and visualization of human tears using alternate light sources for forensic purposes

The current scientific techniques for locating body fluids focus on quick and effective methodologies for easy and reliable identification. Efficient detection and identification of body fluids play a vital role in establishing the ‘corpus delecti’ of a crime. Non-destructive techniques such as the use of Alternate Light Sources (ALS) have been exploited for crime scene searches over large areas and detection of body fluids such as blood, semen, vaginal secretions, and saliva on a range of substrates. Tears are rarely found but can be considered as potential body fluid evidence due to their unique biochemical and molecular properties. Tears are secreted in response to physical or emotional stimuli. Due to the small volume of secretions, they are often overlooked in the crime scene. Tears may be found on surfaces such as clothing, bedding, tissue, handkerchief, or balaclava. The use of ALS to locate tears on tissue paper and fabric surfaces was tested which were not apparent to the naked eye. Tears stains were successfully detected on surfaces of forensic interest with varying sample ages up to three months with a broad excitation spectrum between 254 nm and 410 nm. Dried stains on tissue paper and fabric substrates were better detected with sharp margins, clear stain pattern visibility, and fluorescence intensity in comparison with moist and fresh stains. Tears stains can hence be detected with the use of ALS and suitable filter combinations under normal conditions and do not require any specific settings to locate them. These findings are suggestive for easy and quick identification of tears on large surfaces and as a presumptive test for forensic casework evidence examination.     

Volume Determination of Fresh and Dried Bloodstains by Means of Optical Coherence Tomography

The volume of bloodstains found on crime scenes may help forensic investigators reconstruct the location and kinematics of bloodletting events, as stain size, volume, and impact velocity are related. Optical coherence tomography was used as a method to determine the volume and volume ratio of dried and fresh bloodstains on both glass and irregular surfaces or deposited with an impact velocity. The volume of blood drops deposited on smooth glass surfaces was measured within a deviation of 2%. This deviation increased for droplets on irregular surfaces or deposited with an impact velocity. The volume ratio of dried and fresh bloodstains was equal to 19–28% depending on the individual donor and on the use of an anticoagulant. Optical coherence tomography is a good method to determine the volume of fresh and dried bloodstains in laboratory conditions and allows accurate determination of the dry/fresh ratio.     

荧光黄湿粉显现手印方法的初步研究

目的研发一种具有荧光特性的黄湿粉,以提取遗留在不同客体上的不同种类的手印。方法在100mL温水中加入适量的表面活性剂,溶解后加入100g荧光黄颜料,选用不同种类客体及不同种类物质手印进行显现实验,比较显现效果;结果遗留在光滑非渗透性客体及半渗透性客体表面的汗潜、油潜手印,显出的手印纹线流畅、反差强、荧光强;结论荧光黄湿粉可适用于光滑非渗透性客体及半渗透性客体表面新鲜或较新鲜汗潜手印、油潜手印及血潜手印的显现。     

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.     

The Influence of Selected Fingerprint Enhancement Techniques on Forensic DNA Typing of Epithelial Cells Deposited on Porous Surfaces

Fingerprints deposited at crime scene can be a source of DNA. Previous reports on the effects of fingerprint enhancement methods have focused mainly on fingermarks deposited in blood or saliva. Here, we evaluate the effects of fingerprint enhancement methods on fingerprints deposited on porous surfaces. We performed real‐time quantification and STR typing, the results of which indicated that two methods (iodine fuming and 1,2‐indanedione in ethyl acetate enhancement) had no effect on the quantity of DNA isolated and resultant STR alleles when compared to control samples. DNA quantities and allele numbers were lower for samples enhanced with silver nitrate and 1,2‐indanedione in acetic acid when compared to control samples. Based on DNA quantity, quality, and observable stochastic effects, our data indicated that iodine fuming and 1,2‐indanedione in ethyl acetate were the preferred options for the enhancement of fingerprints on porous surfaces.     

A Silver‐Stain Modification of Standard Histological Slide Preparation for Use in Anthropology Analyses

The traditional histology method typically employed by forensic anthropologists involves plastic embedding of undecalcified bone. The embedded sample is then cut by a diamond blade saw and ground to the required thickness of ~50–100 microns using a grinder. There are several limitations to this method: Cement lines may be blurred; depth‐of‐field artifacts may result from viewing thick sections; and medicolegal offices with limited budgets may not be able to invest in additional equipment or training for this method. A silver nitrate stain modification of the standard histology preparation technique of decalcified bone is presented. The benefits of this technique are that: Cement lines are viewed clearly; no depth‐of‐field artifacts are present; and because this is a modification of the standard technique used by histology laboratories typically employed by medicolegal offices, no additional equipment or training is required.