Chemical Enhancement Techniques of Bloodstain Patterns and DNA Recovery After Fire Exposure*

Abstract: It is common in forensic casework to encounter situations where the suspect has set a fire to cover up or destroy possible evidence. While bloodstain pattern interpretation, chemical enhancement of blood, and recovery of deoxyribonucleic acid (DNA) from bloodstains is well documented in the literature, very little information is known about the effects of heat or fire on these types of examinations. In this study, a variety of known types of bloodstain patterns were created in a four‐room structure containing typical household objects and furnishings. The structure was allowed to burn to flashover and then it was extinguished by firefighters using water. Once the structure cooled over night, the interior was examined using a bright light. The bloodstains were evaluated to see if the heat or fire had caused any changes to the patterns that would inhibit interpretation. Bloodstain patterns remained visible and intact inside the structure and on furnishings unless the surface that held the blood was totally burned away. Additionally, a variety of chemical techniques were utilized to better visualize the patterns and determine the possible presence of blood after the fire. The soot from the fire formed a physical barrier that initially interfered with chemical enhancement of blood. However, when the soot was removed using water or alcohol, the chemicals used, fluorescein, luminol, Bluestar^®, and Hemastix^®, performed adequately in most of the tests. Prior to DNA testing, the combined phenolphthalein/tetramethyl benzidine presumptive test for the presence of blood was conducted in the laboratory on samples recovered from the structure in an effort to assess the effectiveness of using this type of testing as a screening tool. Test results demonstrated that reliance on obtaining a positive presumptive result for blood before proceeding with DNA testing could result in the failure to obtain useful typing results. Finally, two DNA recovery methods (swabbing the stain plus cutting or scraping the stain) were attempted to evaluate their performance in recovering samples in an arson investigation. Recovery of DNA was more successful in some instances with the swabbing method, and in other instances with the cutting/scraping method. Therefore, it is recommended that both methods be used. For the most part, the recovered DNA seemed to be unaffected by the heat, until the temperature was 800°C or greater. At this temperature, no DNA profiles were obtained.     

The role of hydrogen cyanide and carbon monoxide in fire casualties: a prospective study

Determinations of blood cyanide and carboxyhemoglobin concentrations were performed in 18 victims found dead in buildings after fires during a 2-year period. The results indicated that 50% of the victims had been exposed to toxic levels of hydrogen cyanide and 90% to toxic levels of carbon monoxide. Lethal concentrations of carbon monoxide were found in 83% of the victims. In one case a lethal blood cyanide but a non-toxic blood carboxyhemoglobin value was found. It is concluded that carbon monoxide appears to be more important than hydrogen cyanide as a toxic agent in the fire atmosphere, but cyanide poisoning without carbon monoxide poisoning may, under certain circumstances, be the cause of death in fire victims.     

The use of DNA statistics in criminal trials

In a number of recent cases in the UK, convictions have been quashed by the Court of Appeal on the grounds that the jury had been misdirected as to the factual significance of random occurrence statistics. The mathematical basis on which those statistics are calculated was reviewed and recent appeal cases involving DNA evidence in the UK and the US were examined. It was found that a widespread misconception exists regarding the random occurrence ratio and its relationship with probability of guilt. It is in fact impossible to relate the two with any degree of accuracy without consideration of social and demographic factors particular to a case as well as any non-DNA evidence obtained.     

Never say never. Negligible carboxyhemoglobin in the victim of a smoldering mattress fire

For many years, a high blood carboxyhemoglobin concentration has been used as a criterion for determining that a victim of conflagration was alive in the fire. We report a case in which a man died from the combined effects of burns and hypertensive cardiovascular disease. He had a negligible blood carboxyhemoglobin concentration, but the environmental evidence and autopsy findings are indicative of life in the fire, which arose in a smoldering mattress. We conclude that uncritical, rigid adherence to the requirement that fire victims have high carboxyhemoglobin concentrations can be misleading.     

Evaluation of the placenta in a stillborn fetus to estimate the time of death

The authors present a case of a presumably unknown pregnancy, in which the newborn was found dead in the bathroom. The child was considered stillborn and the death due to natural causes. The literature on estimation of the time of fetal death is reviewed. It has been reported that certain placental histological changes are useful in predicting the time of death in stillborn fetuses, but little has been published about their potential role. Furthermore, parameters evaluated by literature in examining the placenta for determining time of fetal demise in cases of stillbirth are not uniform in the few studies that have been published. We emphasize that any attempt to estimate the time of fetal death without an adequate knowledge of placental morphological changes is futile and forensically unjustifiable, and that a comprehensive placental, external, and histological examination of the fetus is still the method of choice to gain a reliable forensic answer.     

Gruesome Evidence and Emotion: Anger, Blame, and Jury Decision-Making

Judges assume that gruesome evidence can influence juror verdicts, but little is known about the manner in which the influence is manifested. In a 2 × 3 study that varied the gruesome content of photographic and verbal evidence, gruesome verbal evidence did not influence mock juror emotional states, and had no impact on the conviction rate. Mock jurors who saw gruesome photographs, compared with those who saw no photographs, reported experiencing significantly more intense emotional responses, including greater anger at the defendant. The conviction rate when visual evidence in the form of gruesome or neutral photographs was included was significantly higher than the conviction rate without photographic evidence. Mean ratings of the inculpatory weight of prosecution evidence by mock jurors presented with gruesome photographs were significantly higher than those by mock jurors who did not view any photographs. Further analyses revealed that mock juror anger toward the defendant mediated the influence of the gruesome photographs in enhancing the weight of inculpatory evidence.     

The forensic examination of structural fires in Victoria,Australia: Decision-making processes and impact on judicial outcomes

There is a body of published research that has evaluated the contribution of forensic science to the criminal justice system, but many disciplines of forensic science remain unexplored in this regard. The aim of this study was to examine the contribution that forensic fire examination services provide to criminal investigations and court processes in arson cases. Forensic fire examination services differ in a number of ways to the disciplines covered in previous research on the impact of forensic evidence on justice outcomes. Forensic fire examinations involve a combination of scene examination and laboratory analyses, and the results can provide critical evidence of whether an incident that has occurred is a criminal offence (i.e. whether a fire has occurred as the result of an act of arson). Forensic fire examination is also a discipline that has faced challenges and undergone development in recent decades regarding its scientific basis and the issue of contextual bias. In this study, data were collated for 273 structural fires that were examined by the forensic fire services in Victoria, Australia. In this jurisdiction, scene and laboratory forensic services are delivered within short time frames with a focus on providing impartial scientific and investigative services to assist criminal investigations conducted by police. The current dataset was highly skewed in terms of criminal justice outcomes and was not suitable for conducting the planned statistical analyses. Nonetheless, the pattern of findings obtained suggested that the inclusion of forensic evidence which supported the prosecution of arson may be associated with an increased likelihood of suspects being charged and defendants found guilty. Examination of the decision-making process of the forensic fire examiners has provided insight into the variety of evidence that is considered by forensic experts in reaching the important conclusion about the origin and cause of structural fires.     

铜导线一次和二次短路熔痕的显微共聚焦激光拉曼光谱特征研究

目的 为了判定火灾发生的原因,依据激光拉曼光谱(RMS)能够反映出经过不同高温热处理炭材料的石墨化程度,以此来探索电气短路判定的技术依据.方法 利用显微共聚焦激光拉曼光谱仪对火灾中不同环境下生成的铜导线短路熔痕表面碳痕斑进行检测分析,利用碳痕斑两个拉曼特征位移峰的比值,计算不同短路熔痕表面碳化斑的石墨化度.结果 铜导线的一次短路、二次短路和火烧熔痕上残留碳斑石墨化度不同,一次短路熔珠碳痕的石墨化度R值最小,火烧熔痕的石墨化度R值最大.结论 该研究建立了显微激光拉曼光谱法无损检测分析铜导线短路熔痕的新方法.     

The Value of CCTV Surveillance Cameras as an Investigative Tool: An Empirical Analysis

There has been extensive research on the value of closed-circuit television (CCTV) for preventing crime, but little on its value as an investigative tool. This study sought to establish how often CCTV provides useful evidence and how this is affected by circumstances, analysing 251,195 crimes recorded by British Transport Police that occurred on the British railway network between 2011 and 2015. CCTV was available to investigators in 45% of cases and judged to be useful in 29% (65% of cases in which it was available). Useful CCTV was associated with significantly increased chances of crimes being solved for all crime types except drugs/weapons possession and fraud. Images were more likely to be available for more-serious crimes, and less likely to be available for cases occurring at unknown times or in certain types of locations. Although this research was limited to offences on railways, it appears that CCTV is a powerful investigative tool for many types of crime. The usefulness of CCTV is limited by several factors, most notably the number of public areas not covered. Several recommendations for increasing the usefulness of CCTV are discussed.     

OpenLV: Empowering investigators and first-responders in the digital forensics process

The continuing decline in the cost-per-megabyte of hard disk storage has inevitably led to a ballooning volume of data that needs to be reviewed in digital investigations. The result: case backlogs that commonly stretch for months at forensic labs, and per-case processing that occupies days or weeks of analytical effort. Yet speed is critical in situations where delay may render the evidence useless or endanger personal safety, such as when a suspect may flee, a victim is at risk, criminal tactics or control infrastructure may change, etc. In these and other cases, investigators need tools to enable quick triage of computer evidence in order to answer urgent questions, maintain the pace of an investigation and assess the likelihood of acquiring pertinent information from the device.This paper details the design and application of a tool, OpenLV, that not only meets the needs for speedy initial triage, but also can facilitate the review of digital evidence at later stages of investigation. With OpenLV, an investigator can quickly and safely interact with collected evidence, much as if they had sat down at the computer at the time the evidence was collected. Since OpenLV works without modifying the evidence, its use in triage does not preclude subsequent, in-depth forensic analysis. Unlike many popular forensics tools, OpenLV requires little training and facilitates a unprecedented level of interaction with the evidence.     

Assessing the quality of footwear marks recovered from simulated graves

Footwear marks are one of the most frequently encountered evidence types recovered from a crime scene and can provide valuable scene intelligence regarding potential suspects. It has been acknowledged that impressions of footwear and tools can be recovered from graves, but previous studies have only focused on tool mark recovery. This has led to a lack of published information regarding footwear mark recovery from graves. It is therefore important to demonstrate whether the recovery of footwear marks is feasible and, if so, under what conditions this can be achieved. To address recovery, this study, placed 60 three dimensional (3D) impressions of footwear marks within 60 simulated graves. This was done to assess time (1, 2, 4 months) and at known depths (20, 30, 40 cm). The footwear marks within the graves were covered with clothing or left uncovered. The shoe’s design patterns were grouped and counted in a photographic comparison between the 3D footwear impressions, placed within the test-pits, and any recovered impressions. A grading system was adapted by the authors to score the quality of footwear impressions observed during recovery. The results demonstrate that the preservation and recovery of footwear impressions from graves is feasible. The simulated graves covered with clothing showed better preservation of footwear impressions, but there was no clear evidence that time or depth had an effect. The authors note that careful consideration and vigilant excavation skills are needed when excavating graves which may bear potential footwear marks, as their recovery will lead to an increased amount of intelligence that can link suspects to homicide scenes.     

Using Raman Spectroscopy to solve crime: inks, questioned documents and fraud

Raman microscopy is becoming a tool of major importance in forensic analysis, particularly of drugs and explosives. It is a non-invasive, non-destructive chemical probe allowing samples to be examined in their entirety without any preparation. This paper demonstrates the use of the technique as a general tool for inks analysis. Furthermore, it addresses two important issues that historically have been extremely difficult for the professional document examiner, namely, comparison of black ballpoint inks and the chronological sequencing of crossed ink lines. We show that Raman can successfully distinguish between a representative sample of commercially available black ballpoint inks. This data has been converted into a database for future reference. A method for chronological sequencing of crossed ink lines has been developed using confocal Raman microscopy. Case study work has shown the feasibility of this approach.     

The evaluation of the extent of transporting or "tracking" an identifiable ignitable liquid (gasoline) throughout fire scenes during the investigative process

Tests have determined that boots or shoes of individuals at a fire scene do not transport sufficient contaminants ("tracking") through the fire scene to produce a positive laboratory result for the presence of gasoline in a fire scene that was not present at the time of the fire. Questions about the validity of forensic laboratory results have been raised on the basis that low-level gasoline residues detected in the laboratory samples could have been the result of transporting the residue by footwear contaminated from the fire scene ("tracking"). The data collected in this study establish that "tracking" does not lead to false-positive laboratory results. Canines trained and experienced in the detection of trace ignitable liquid residues were also utilized in this study. The canine results confirmed that properly trained canines show a higher sensitivity than do standard ASTM laboratory techniques for fire debris analysis. In a few cases, canines responded to contamination, but laboratory testing (which is the definitive indicator) did not produce positive results.     

Hemorrhage of the head and neck in death by burning

The 202 deaths connected with burns in 1976-1986 included 134 in which death occurred during the fire. In 49 cases the face was so badly charred that it was not possible to judge whether hemorrhage had occurred in the eyelids and/or conjuctivae. Such blood extravasation was seen in 14 of the remaining 85 cases, taking the form of petechiae in some cases and in others the form associated with more extensive extravasation, in some cases hemolytic. No other features known to cause such hemorrhages were present, so that they are attributed to the burning process itself. Signs of extensive pronounced burns were found in 13 of these cases, and it seemed that high-degree burns on the neck and trunk with less severe burns on the head were particularly likely to be associated with such hemorrhages. In most cases the flames had quickly come into direct contact with the body (clothing, bed or chair had caught fire), leading to rapid death, as documented by the fact that usually very little or no soot at all had been aspirated and by the low level of carbon monoxide intoxication (max. COHb 22%). One plausible explanation for the development of hemorrhage is the supposition first expressed over 20 years ago that when the circulation is maintained rapid burn-induced shrinkage of the skin of the neck has the effect of strangulating the victim; hemorrhage of eyelids and/or conjunctivae in such cases be could regarded as a vital reaction to the effect of fire. This is particularly significant, insofar as evidence of hemorrhage of this kind was found predominantly in bodies in which other vital signs indicative of the effects of burning were sparse and slight or even totally absent. In addition, specific examination of the laryngeal area revealed congestion-induced extravasation at various points, as well as petechial hemorrhage in the mucous membrane.     

Application of computational fluid dynamics modelling in the process of forensic fire investigation: problems and solutions

Fire modelling has been gaining more and more interest into the community of forensic fire investigation. Despite an attractiveness that is partially justified, the application of fire models in that field of investigation rises some difficulties. Therefore, the understanding of the basic principles of the two main categories of fire models, the knowledge of their effective potential and their limitations are crucial for a valid and reliable application in forensic science. The present article gives an overview of the principle and basics that characterise the two kinds of fire models: zone models and field models. Whereas the first ones are developed on the basis of mathematical relation from empirical observations, such as stratification of fluid zones, and give a relatively broad view of mass and energy exchanges in an enclosure, the latter are based on fundamentals of fluid mechanics and represent the application of Computational Fluid Dynamics (CFD) to fire scenarii. Consequently, the data that are obtained from these two categories of fire models differ in nature, quality and quantity. First used in a fire safety perspective, fire models are not easily applied to assess parts of forensic fire investigation. A suggestion is proposed for the role of fire modelling in this domain of competence: a new tool for the evaluation of alternative hypotheses of origin and cause by considering the dynamic development of the fire. An example of a real case where such an approach was followed is explained and the evaluation of the obtained results comparing to traces revealed during the on-site investigation is enlightened.     

Recovery of fingerprints from fire scenes and associated evidence.

A lack of information concerning the potential recovery of fingerprints from fire scenes and related evidence prompted several research projects. Latent prints from good secretors and visible prints (in blood) were placed on a variety of different surfaces and subsequently subjected to "real life" fires in fully furnished compartments used for fire investigation training purposes. The items were placed in various locations and at different heights within the compartments. After some initial success, further tests were undertaken using both latent and dirt/grease marks on different objects within the same types of fire compartments. Subsequent sets of tests involved the recovery of latent and visual fingerprints (in blood, dirt and grease) from different types of weapons, lighters, plastic bags, match boxes, tapers, plastic bottles and petrol bombs that had been subjected to the same fire conditions as previously. Throughout the entire series of projects one of the prime considerations was how the resultant findings could be put into practice by fire scene examiners in an attempt to assist the police in their investigations. This research demonstrates that almost one in five items recovered from fire scenes yielded fingerprint ridge detail following normal development treatments.     

Complex suicide by ethanol intoxication and inhalation of fire fumes in an old lady: interdisciplinary elucidation including post-mortem analysis of congener alcohols

An 88-year-old woman committed suicide by drinking a toxic amount of highly concentrated alcohol and setting two rooms of her flat on fire. As there was not enough oxygen, the fire went out, however. At autopsy, no thermal lesions were found on the body, but soot depositions in the airways and a COHb value of 14% pointed to the inhalation of fire fumes. The ethanol concentration in femoral blood was 6.62 per mille. The gastric mucosa was fixed by the ingested alcohol and showed hardly any autolytic changes despite a post-mortem interval of five days. Congener analysis of the gastric contents and the femoral blood indicated the uptake of a fruit distillate or its foreshot.     

Evaluation of human brain damage in fire fatality by quantification of basic fibroblast growth factor (bFGF), glial fibrillary acidic protein (GFAP) and single-stranded DNA (ssDNA) immunoreactivities

Burns and inhalation of toxic gases, including carbon monoxide (CO) and cyanide, which are produced by combustion, are major factors involved in fire death. The present study immunohistochemically investigated basic fibroblast growth factor (bFGF), glial fibrillary acidic protein (GFAP) and single-stranded DNA (ssDNA) in the brains of fire fatalities (n=49) to examine the differences between fatal burns and CO intoxication, compared with those in cardiac deaths (n=24) and mechanical asphyxiation cases (n=23). In acute fire fatality, neuronal ssDNA immunopositivity in the cerebral cortex of the parietal lobe was high in both fatal burns and fatal CO intoxication, but that of the pallidum was higher for CO intoxication than for burns. The number of neurons was decreased in prolonged fire deaths, irrespective of the severity of burns or CO intoxication, but glias were increased in cases of fatal burns. Prolonged deaths due to burns had a higher glial bFGF immunopositivity in the cortex and white matter, higher and lower glial GFAP immunopositivity in the cortex and white matter, respectively, and a low neuronal ssDNA immunopositivity in the cerebral cortex and hippocampus. In prolonged deaths due to CO intoxication, however, glial bFGF and GFAP immunopositivities were low at each site, but neuronal ssDNA immunopositivity showed a higher value. These observations suggest increased cerebral neuronal ssDNA immunopositivity to be a finding of vitality in acute fire death, and a neuronal loss accompanied by active glial responses after severe burns, and a neuronal loss and progressive apoptosis without glial responses after CO intoxication to be characteristic in prolonged death.     

The management of domain irrelevant context information in forensic handwriting examination casework

That domain irrelevant context information can potentially bias human decision making processes is accepted in the psychological sciences. Although many forensic pattern examination sciences use human perceptual and cognitive processes almost exclusively to form opinions regarding evidence, we have been slow to engage with any procedure that might control for any potential effects associated with context information. The critics of pattern evidence have described how opinions may be unintentionally incorrectly formed and how bodies of evidential information might conspire to form cases where the sum of the totality of the evidence may be significantly more than its specialist parts. Given the body of evidence supporting the potentially serious implications of domain irrelevant information, it was decided to introduce a context management scheme at the Document Examination Unit of the Victoria Police Forensic Services Department. Existing laboratory wide evidence submission procedures were modified in the scheme such that, as far as was agreed to be practical, all handwriting cases were stripped of all but essential information for carrying out examination and comparison tasks. As yet no negative outcomes have been reported as a result of the scheme implementation.     

Flaws in the U.S. Food and Drug Administration's rationale for supporting the development and approval of BiDil as a treatment for heart failure only in black patients

The U.S. Food and Drug Administration's (FDA) rationale for supporting the development and approval of BiDil (a combination of hydralazine hydrochloride and isosorbide dinitrate; H-I) for heart failure specifically in black patients was based on under-powered, post hoc subgroup analyses of two relatively old trials (V-HeFT I and II), which were further complicated by substantial covariate imbalances between racial groups. Indeed, the only statistically significant difference observed between black and white patients was found without any adjustment for potential confounders in samples that were unlikely to have been adequately randomized. Meanwhile, because the accepted baseline therapy for heart failure has substantially improved since these trials took place, their results cannot be combined with data from the more recent trial (A-HeFT) amongst black patients alone. There is therefore little scientific evidence to support the approval of BiDil only for use in black patients, and the FDA's rationale fails to consider the ethical consequences of recognizing racial categories as valid markers of innate biological difference, and permitting the development of group-specific therapies that are subject to commercial incentives rather than scientific evidence or therapeutic imperatives. This paper reviews the limitations in the scientific evidence used to support the approval of BiDil only for use in black patients; calls for further analysis of the V-HeFT I and II data which might clarify whether responses to H-I vary by race; and evaluates the consequences of commercial incentives to develop racialized medicines. We recommend that the FDA revise the procedures they use to examine applications for race-based therapies to ensure that these are based on robust scientific claims and do not undermine the aims of the 1992 Revitalization Act.