Effect of Different Stains at the Simulated Crime Scene

Transcription

1 Effect of Different Stains at the Simulated Crime Scene Samir Kumar Bandyopadhyay #1, Nabanita Basu *2 # Professor, Department of Computer Science & Engineering, University of Calcutta, JD Block, Sector III, Salt Lake, Kolkata , West Bengal, India * Research Scholar, Department of Computer Science & Engineering, University of Calcutta and BPA Certified JD Block, Sector III, Salt Lake, Kolkata , West Bengal, India Abstract In this paper intend to document the stain type we can see or might expect to see on the clothes of an individual when he/she is a victim, perpetrator or a simple bystander in the event of a head hit of a victim using a stick, rod, axe etc. (The instruments of head hit shall be decided in discussion and study of court proceedings of several violent cases that have so far been solved) in an indoor setting. Based on the velocity of hit, stain type on cloth of an individual, number of hits, distance between the victim, perpetrator and bystander, relative position of the three at the time of hit, movement of any party before probable subsequent hits, direction of movement of weapons and people, room temperature, humidity, room dimensions, person height, weight,using Bayesian networks, correlation and regression we would try to probabilistically infer the position of an individual (victim, perpetrator, bystander(if any)). The relevance of the article lies in the fact that analysts having clear idea of how these different factors could affect the formation of different weapon transfer stain patterns, shall be in a better position at understanding the probable mechanism that might have led to the formation of the stain. This knowledge is transferable to the study of other murder weapon transfer stain interpretation and shall aid proper sequencing of segments in a criminal event. Keywords Blunt objects, Fabrics, Bystander, Perpetrator, Room and Victim, Foot Prints I. INTRODUCTION Bloodstain pattern analysis can range from the simple to the complex. The trails of blood in a crime scene or castoff blood patterns are reasonably straightforward and understandable. Determining areas of convergence and origin employing string methods or trigonometric methodologies are more complex and call for a trained specialist. The scientific analysis of bloodstain patterns requires extensive training and experience, which goes beyond the normal crime scene process. Furthermore, there are a number of different definitions and opinions by various experts in the field, which tend to confuse the average investigator. Therefore, the author's intention within this article is to illustrate some simple and practical examples of bloodstain pattern recognition and documentation along with photos and description. The terms used to describe bloodstain patterns, are oftentimes confusing to the average investigator. Such terms as bloodstain spatter or splatter might be used interchangeably. The reference to pattern analysis or pattern interpretation further confuses the issue because the word interpretation connotes subjectivity to the scientific analysis and evaluation of bloodstain pattern evidence. According to the recognized experts in the field the proper term is Bloodstain Pattern Analysis (BPA), which implies a structured approach in evaluating that, which is to be examined. It is one of several specialties in the field of forensic science. The science of bloodstain pattern analysis applies scientific knowledge from other fields to solve practical problems. Bloodstain pattern analysis draws on biology, chemistry, math, and physics among scientific disciplines. After the investigation is complete, dispose of gloves, masks, and gowns contaminated by blood or body fluids in a biohazard bag and wash hands thoroughly with an antiseptic hand rinse. Before returning to the station, wash hands again with water and a bacterial liquid hand wash, i.e., Bacti- Stat. Restrict the number of investigators on the scene who may come in contact with the scene of the potential infection exposure. Advise any investigators on the scene who may come in contact with the scene of the potential infection exposure. Decontaminate all equipment used prior to your return to the station. Change clothing contaminated with blood or other body fluids immediately and decontaminate. Dispose of contaminated supplies as ISSN: Page 75

2 recommended in this protocol. Skin provides a very effective barrier for the prevention of infectious diseases. Wash all contact areas as soon as possible after exposure to help prevent contamination. Wounds such as cuts, sores, and breaks in the skin, regardless of the size, provide an entrance for infection into the body and should be properly bandaged. Report all significant exposures to blood or other body fluids within 24 hours of exposure. Blood is present in most crimes scene involving violence and therefore presents the investigator with additional information to determine the sequence of events, which may have taken place between the victim and the assailant. Bloodstain patterns at the scene or from the clothing of principals in a case can be used to confirm or refute assumptions concerning events and their sequence. In addition, bloodstain patterns can illustrate the position of the victim, such as standing, sitting, or lying. Bloodstain evidence can also show evidence of a struggle. Furthermore an effective bloodstain pattern analysis can confirm or refute statements made by principals in the case. For example, "Are stain patterns on a suspects clothing consistent with his reported actions? Or, "Are stain patterns on a victim or at a scene consistent with accounts given by witnesses or the suspect"? Locard's Principle that the perpetrator will take away traces of the victim and the scene, the victim will retain traces of the perpetrator and may leave traces of himself on the perpetrator and the perpetrator will leave behind traces of himself at the scene many times is borne out in the evaluation and retrieval of bloodstain pattern evidence. Crime scene reconstruction and the presence of bloodstains and patterns in the scene are very important considerations in the crime scene search process. The discipline of bloodstain pattern analysis (BPA) considers the location, shape, size, distribution and other physical characteristics of the bloodstains in the scene. Blood flows will always obey gravity. Hence, the presence of blood flow that seemingly does not follow ordinary gravitational pull might indicate movement of the victim or disturbance of the scene by the offender or someone else who arrived in the scene after the event including first responder. The search of the crime scene is the most important phase of the investigation conducted at the scene. The retrieval of bloodstain pattern evidence begins with the effective search of the scene. Physical evidence refers to any tangible article, small or large, which tends to prove or disprove a point in question. It may be used to reconstruct the crime, identify participants, or confirm or discredit an alibi. Homicide and sexual assault crime scenes usually contain an abundance of physical or trace evidence especially bloodstain pattern evidence. The systematic search, collection, and preservation of physical evidence are the goals of the crime scene search. Transient Evidence is temporary in nature. It can include odors, temperature, imprints and indentations in soft or changing materials such as butter, wet sand, snow or mud. It also refers to markings such as lividity, or blood spatters on moveable objects. Pattern Evidence is produced by contact. Blood splatter, glass fracture patterns, fire burn patterns, Furniture position patterns, projectile trajectory, tire marks, M.O., clothing or article patterns, and powder residue patterns are considered pattern evidence. Conditional Evidence is caused by an action or event, such as lighting conditions at a crime scene, odor, color, direction of smoke; flame (color, direction, temperature); location of evidence including bloodstain evidence in relation to the body. Transfer Evidence is generally produced by the physical contact of persons, objects, or between persons or objects. It is characterized by the LINKAGE CONCEPT. The bloodstains and patterns are classified based on their physical features of size, shape, location, concentration and distribution. Classification however, is but one step in the overall analysis. Classification sets the stage for the analyst to define more effectively a source event for any given stain. Recording the bloodstain patterns in the scene is a major facet of the investigation. It is extremely important that this be accomplished before anything is touched or moved at the scene. Photographs should be taken depicting the overall scene followed by medium range and close-up views of ISSN: Page 76

3 the patterns. A scale of measure should be included with the close-up photographs. Figure 1: Multiple spatter patterns in different forms. There is lowvelocity drip, medium velocity drip near toilet bowl, and high velocity on the floor and pooling near the tub. The crime scene sketch is a simple line drawing that indicates the position of the body in relation to fixed and significant objects in the scene. It supplements both the written reports and the crime scene photographs. Photographs, because of camera perspective and distortion, do not always depict the exact location in which objects are situated or the relation of one object to another. The crime scene sketch is an excellent visual aid, which allows for the removal of unnecessary details and the inclusion of significant material. A sketch f the bloodstain pattern will contain only essential items necessary for the analysis, whereas regular crime scene photographs will be overcrowded with detail. Bloodstain Pattern Analysis (BPA) is a discipline, which requires formal training coupled with years of practical experience. The discipline of bloodstain pattern analysis considers the location, shape, size, distribution and other physical characteristics of the bloodstains in the scene. The Scientific Working Group on Bloodstain Pattern Analysis entitled (SWGSTAIN) was created in 2002 and has established many of the current protocols. Blood was legally procured from Kolkata Municipal Pig Slaughter House, Tangra Kolkata, India. Given that fresh blood coagulates over time, 1100 IU of Heparin Injection was added to fresh pig blood to preserve the colloidal consistency of blood. It might be interesting to mention that adding anticoagulant does not alter the viscosity and specificity of the Non- Newtonian fluid, blood. II. REVIEW WORKS Locard s exchange principle states that every time an individual makes contact with another person, place or thing, it results in an exchange of physical materials [1]. Locard believed that no matter what a perpetrator does or where he goes, by coming in contact with things at or around a crime scene he can leave all sorts of evidence, including DNA, fingerprints, footprints, hair, skin cells, blood, body fluids, pieces of clothing fibers and more [1]. While the criminal leaves something at the crime scene he is also expected to take something away from the scene with him [1]. On a very loose connect it might be said that when killing an individual with a hammer hit the criminal might take away the murder weapon with him but at the same time he might end up leaving behind bloody stains of the blood bearing hammer at the crime scene. A bloodstain resulting from contact between a blood-bearing surface and another surface has been termed as Transfer Stain by the International Association of Bloodstain Pattern Analysts (IABPA) [2]. Thus this work is particularly directed at studying different transfer stain patterns at a crime scene. The scientific study/interpretation of bloodstain patterns at a crime scene, provide invaluable evidence for sequencing, reconstruction of events that might have occurred at the crime scene. As per the Federal Bureau of Investigation(FBI) each year a greater number of people die as a consequence of blunt force trauma compared to the number of people who are killed with a rifle or shot gun. From documentation phase to final interpretation, bloodstain pattern analysis is deeply rooted in the principles of physics, fluid mechanics, medical science, computer science, mathematics etc. Bloodstains are classified into three basic types: passive stains, transfer stains and projected or impact stains. Passive stains include drops, flows and pools, and typically result from gravity acting on an injured body. Transfer stains result from objects coming into contact with existing bloodstains and leaving wipes, swipes or pattern transfers behind such as a bloody shoe print or a smear from a body being dragged. Impact stains result from blood projecting through the air and are usually seen as spatter, but may also include gushes, splashes and arterial spurts. The authors conducting the study are particularly interested in recording, analysis and interpretation of the Transfer Stain and Saturation Stain patterns one can expect to see in the event of head hit by a blunt ended object (such as hammer, golf stick, candle stand etc.)[1-2]. Given the large possibility of instruments that can be easily obtained and hence deliver blunt force injuries to the human skull, the authors decided to particularly focus on the possible Transfer and Saturation stain patterns formed at a crime scene as a result of assault particularly with blunt ended objects. Thus in a violent crime scene with sufficient amount of bloodshed, bloodstain pattern analysis often plays a significant role in proving or refuting the statements of the suspect, victim, bystander/eyewitness(if any) within the juridical setting. The stains along with the wound suffered by the victim/s could also be used for part/full reconstruction of crime scenes. These case studies particularly set out the background for this paper. On December 13, 2010, Dave Toplikar s report reinforced the importance of proper ISSN: Page 77

4 recording and hence interpretation of weapon transfer stains at a crime scene [3]. Dave s report in the Las Vegas Sun highlighted how the presence of a hammer imprint in blood pool was capable of influencing the decision of the jury and the fate of Mr.Edward Preciado Nuno, an ex-fbi special agent [3]. While Daniel Holstein, senior crime scene analyst in Metro police and a certified expert in bloodstain pattern analysis, gave the case a new dimension by focusing on the hammer imprint that matched the size of the hammer that lay close to the apparent victim s hand, Thomas Pitaro the defense attorney clearly marked out that the hammer imprint theory was not mentioned in the police report and was only added much later [3]. There are two lessons to be learnt from the juridical proceedings of this particular case. Firstly, transfer stains often go unattended and hence unrecorded by most law enforcement officials. Secondly, when analyzed in relation to suspect, eyewitness testimony or other relevant circumstantial evidence, weapon transfer stains could actually give criminal juridical proceedings a new dimension [3], a new perspective. This paper aims at documenting possible domain knowledge that could help crime scene investigators identify or sequence events based on hammer imprints /hammer like imprints in a blood pool or blunt object transfer stains together with other circumstantial evidence. The hypotheses that the authors intend to test in this work can be summarized as follows The presence of a hammer or hammer-like transfer stain or imprint in blood pool does not necessarily imply that that the particular tool has been used as the murder weapon in the particular crime scene. Bloodstain imprints formed when a hammer is placed in a blood pool and then placed on a different surface and the case when a sufficient quantity of blood drips or falls under gravity from a height of 10 cms (say) over a hammer lying on a plain, non-absorbent surface are particularly different. In particular, Professor MacDonell s contribution to the research and interpretation of bloodstain pattern analysis since 1971 stands commendable till date [5a-5b]. The Association of Crime Scene Reconstruction defines reconstruction as the use of scientific methods, physical evidence, deductive and inductive reasoning and their inter-relationships to gain explicit knowledge of the series of events that surround the commission of a crime. [4] T. Bevel and M. Gardener in their book on Blood Stain Pattern Analysis 3rd edition- An Introduction to Crime Scene Reconstruction have explicitly explained the different types of bloodstain patterns as described by the International Association of Bloodstain Pattern Analysts [4]. The book also contains a detailed classification of bloodstain patterns. How patterns vary with difference in angle of impact, fall height, temperature, surface texture, surface absorption capability etc. has been neatly documented in the book [4]. Dr. Brodbeck s article on Introduction to bloodstain pattern analysis highlights important factors when documenting the bloodstain patterns at a crime scene [6]. James, Sutton and Kish s book on Principles of Bloodstain Pattern Analysis: Theory and Practice also explicitly explains the use of bloodstain evidence and its effective use with other circumstantial evidence for sequencing the events in a particular crime scene [7]. Stuart H. James s book on Scientific and Legal Applications of Bloodstain Pattern Interpretation outlines the rules for documentation and presentation of bloodstain patterns within a juridical setting. Illes et al. presented a set of criteria for selection of patterns in an impact spatter using a statistical model [8]. Proper selection of stains in an impact spatter is particularly important for calculation of the area of origin of the impact that created the particular spatter stain. Shen, Brostow, Cipolla developed an algorithm for automated estimation of a body s 2D location on a floor plan when the body is impacted given that the blood stains are formed as a result of impact spatter[9]. This study is particularly inspired from the work of Barksdale, Sims and Vo in which they compared a reference array of knife impressions with impressions obtained from two real life crime scenes [10]. III. OBSERVATIONS BASED ON EXPERIMENTS CONDUCTED Herbert McDonnell once said, In the course of a trial, both defense attorneys and prosecuting attorneys may lie, witnesses may lie, and the defendant certainly may lie. Yes, even the judge may lie. Only the evidence never lies. But if the evidence is not properly recognized, documented, preserved and processed all we have are attorneys, witnesses, defendants and judges. In line with the words of Herbert McDonnell, Bloodstain Pattern Analysis particularly involves careful scientific study of the static consequences resulting from dynamic bloodletting events. The detailed documentation of bloodstain patterns present at a crime scene often prove to be an evidence of great importance within the courtroom setting. Bloodstain pattern analysis deals with careful study of the distribution, shape, size of bloodstains on a victim, on a suspect, on the floor, on the walls, on the ceiling, on objects at the crime scene. Bloodstain patterns are reconstructive evidence that can be used to evaluate the credibility of the statements provided by a suspect, a victim, a witness within a juridical setting.bloodstain patterns can also be used to sequence events that might have occurred at a crime scene thereby supporting the entire process of crime scene reconstruction. With due help from authorized law enforcement agencies (state police, army) and scripted court ISSN: Page 78

5 proceedings we intend to re-create primary (i.e. Location of the original criminal activity) crime scene and the different sort of blood stains we could see particularly on different sorts of fabrics, floor, ceiling, walls, ground, both indoors and outdoors in a violent crime scene by use of a range of murder weapons (eg. Axe, Knife, Screw-driver, stick etc.). The crime scenario is shown in Figure 2. Figure 3: (a) Cast off Pattern formed on the ceiling (b) Finger Transfer Stain Patterns formed on the walls (c) Wipe pattern formed on the floor, (d) Blood pool together with void patches on left and right side (e) Hand, Violent Knife Crime and Axe transfer stains on floor Primary Crime Scene - Location of the original major criminal activity Indoors Figure 2: A graphical representation of crime scene classification A crime scene where bodily injury has occurred is likely to have some amount of bloodstain evidence present; however, the amount will vary depending on the circumstances of the crime. The type of injury inflicted and the amount of force used will determine the volume and pattern of bloodstains: Sharp force injuries (stabbing): these injuries are caused by an object with a relatively small surface area, such as an ice pick or a knife. Less blood is deposited on the instrument, resulting in a smaller, more linear pattern of stains. Blunt force injuries (hitting or beating): objects inflicting this type of injury are usually larger, such as a bat or hammer. If the object impacts liquid blood, the larger surface area will collect more blood, producing drops of varying sizes. Gunshot injuries: mist-like spatter caused by bullets entering and exiting the body. Figure 4: Blood pool accompanied by left and right void patches. Demonstration of a possible reason/cause for the particular void pattern formation Outdoors Secondary Crime Scene - Location of the subsequent criminal activities Indoors Figure 5: Impression of bloody hand and knife tip on the floor Outdoors But, how does the reconstruction process work? To be even more precise, how can bloodstain patterns be particularly used to reconstruct a crime scene? Crime scene reconstruction is done based on analysis, interpretation and linking of all types of evidence (such as hair strand, sputum, pollen grains, soil particles, shoeprint, bloodstain patterns, fingerprints etc). In order to provide the readers a brief overview of how bloodstains alone can be used for part/full reconstruction of crime scene, the authors simulated a crime scene within the laboratory setting. Figure 3 provides a brief overview of the different stains at the simulated crime scene. Bloodstain patterns formed on the ceiling of the room in Figure 3a reveal that the stains have been formed as a result of repeated to-and fro movement of a bloodstained object in a particular direction. In coherence, Figure 3b represents finger marks on side walls, thereby giving out the impression that someone had probably held on to the wall with bloody hands before falling off. Figure 3c again depicts a drag impression in the floor thereby hinting that some bloody object might have been dragged through the floor. While interpretation of stain patterns in Figure 3 a, b, c was pretty straight forward, interpreting stain patterns in Figure d and e might seem a tad bit challenging. How might have the blood pool been formed in Figure 3d? A close inspection might show that there aren t very many stain patterns nearby other than a hand impression. In this respect it might be interesting to mention that in a violent crime scene that has been witness to blood shedding events, absence of blood in particular areas of the scene can be as integral to crime scene reconstruction as would be the presence of bloodstains. The stain in Figure 3d illustrates that blood had dripped from an object at a certain height and hence formed a pool, but no satellite stains are evident on the left and right patch of the stain, while the top, bottom area have recorded quite a few satellite stains. From the stain or blood pool it can also be predicted that the object from which blood dripped was perpendicular to the target surface (i.e. the floor in this case) at the time of stain formation. The left and right patch has no stains owing to some obstruction that was present at the crime scene during the formation of this particular stain pattern. Figure 4 elucidates the obstruction that was present at the crime scene during the formation of stain 3d. It is rare to find objects at a crime scene as a result of mere co-incidence. Figure 3e represents the transfer stain from a bloody axe. Presence of a bloody axe impression at a crime scene cannot be absolutely co-incidental. However, such stains should always be studied in the light of other circumstantial evidence at the crime scene. A close inspection of stains in Figure 3 d also reveal a bloody hand impression with a knife impression (refer Figure 4and Figure 5). So what might have been the murder weapon in this particular case? Stains on the ceiling and walls reveal that the victim must have been hit on the head with a blunt ended object (could be an axe, a hammer, a stick, a candle stand etc.) and thereby fell off to the ground as a result of fatal head hit. The axe transfer stain in Figure 3d reveals that the bloodstained bloody axe ISSN: Page 79

6 was placed on the ground. So there stands a high probability that the person was hit on the head with the axe. A real crime scene in its turn isn t always simple to interpret. Owing to complex bloodstain patterns formed as a result of simultaneous bloodletting events, presents of 3 or 4 individuals etc. Circumstantial evidence again has an extremely important role to play when interpreting and thereby reconstructing a crime scene based on physical evidence secured from the crime scene. IV. CONCLUSION Based on the velocity of hit, stain type on cloth of an individual, number of hits, distance between the victim, perpetrator and bystander, relative position of the three at the time of hit, movement of any party before probable subsequent hits, direction of movement of weapons and people, room temperature, humidity, room dimensions, person height,weight, using Bayesian networks, correlation and regression we would try to probabilistically infer the position of an individual (victim, perpetrator, bystander(if any)). We intend to study the stain type we can see or might expect to see on the clothes of an individual when he is a victim, perpetrator or a simple bystander in the event of a head hit of a victim using a stick, rod, axe etc. V. REFERENCES [1]. Welding,S(2012,12).Locard s Exchange Principle- Forensic Hand book Retrieved October 22,2014, from Hand book.com/locards-exchangeprinciple/ [2]. SWGSTAIN(2009,11(2).Scientific Working Group on Bloodstain Pattern Analysis: recommended terminology. For Sci Comm. [3]. Toplikar, D. (2010, December 13). Blood stain with hammer imprint shown in ex-fbi agent's murder trial - Las Vegas Sun News. Retrieved from [4]. Bevel, T., & Gardner, R. M. (2002). Bloodstain pattern analysis: With an introduction to crime scene reconstruction (3rd ed.). [5]. a) James, S. H. (1998).Scientific and legal applications of bloodstain pattern interpretation. Boca Raton, FL: CRC Press. b) Ristenbatt III, R. R. (2009). Review of: Bloodstain Pattern Analysis with an Introduction to Crime Scene Reconstruction, 3rd edition. Journal of Forensic Sciences, 54(1). doi: /j x [6]. Brodbeck, S. (2012). Introduction to Bloodstain Pattern Analysis. SIAK Journal- Journal of Police Science and Practice, doi: /ie_2012_e [7]. James, S. H., Kish, P. E., & Sutton, T. P. (2005). Principles of bloodstain pattern analysis: Theory and practice.. Boca Raton, FL: CRC. [8]. James, S. H. (1998). Scientific and legal applications of bloodstain pattern interpretation. Boca Raton, FL: CRC Press. [9]. Shen, A. R., Brostow, G. J., & Cipolla, R. (0). TOWARD AUTOMATIC BLOOD SPATTER ANALYSIS IN CRIME SCENES. Retrieved from Spatter_ShenBrostow.pdf [10] Barksdale, L., Sims, E., & Vo, C. (2004). Knife Impression Bloodstain Patterns. Crime Scene Investigation Special Issue Anil Aggrawal's Internet Journal of Forensic Medicine & Toxicology. Retrieved fromhttp:// ISSN: Page 80