BLOOD SPLATTER ANALYSIS EFFECT OF HEIGHT ON BLOOD

BLOOD SPLATTER ANALYSIS : EFFECT OF HEIGHT ON BLOOD DROPS

BLOOD SPLATTER ANALYSIS • WORKING IN GROUPS OF 4 • 1 RECORDER • 1 PHOTOGRAPHER • 2 TECHNICIANS, 1 PERSON MEASURES ST AND THE 2 ND PERSON CONFIRMS DATA FOR RECORDING FORENSIC SCIENCE : An Introduction by Richard Saferstein Pearson © 2016 2

DIRECTIONS: • USING THE MULTIPLE HEIGHTS GIVEN, RECORD THE DATA • 1 PERSON MEASURE, • 2 PERSON CONFIRM MEASUREMENT • RECORDER DOCUMENT DATA • PHOTOGRAPHER –CAPTURE IMAGES FOR ST ND COMPARISON AND DATA ANALYSIS FORENSIC SCIENCE : An Introduction by Richard Saferstein Pearson © 2016 3

CHAPTER 11 CRIME SCENE RECONSTRUCTION: FORENSIC BLOODSTAIN PATTERN ANALYSIS HOMEWORK: CREATE YOUR OWN NOTES FORENSIC SCIENCE: An Introduction by Richard Saferstein

CRIME SCENE RECONSTRUCTION The method used to support a likely sequence of events by the observation and evaluation of physical evidence, as well as statements made by those involved with the incident, is referred to as reconstruction. FORENSIC SCIENCE: An Introduction by Richard Saferstein 5

CRIME SCENE RECONSTRUCTION Crime-scene reconstruction relies on the combined efforts of medical examiners, criminalists, and law enforcement personnel to recover physical evidence and to sort out the events surrounding the occurrence of a crime. FORENSIC SCIENCE: An Introduction by Richard Saferstein 6

CRIME SCENE RECONSTRUCTION A crime-scene investigator can bring special skills to the reconstruction of events that occurred during the commission of a crime. For example, a laser-beam is used to determine the search area for the position of a shooter who has fired a bullet through a window and wounded a victim. FORENSIC SCIENCE: An Introduction by Richard Saferstein 7

Figure 4– 1 A laser beam is used to determine the search area for the position of a shooter who has fired a bullet through a window and wounded a victim. The bullet path is determined by lining up the victim’s bullet wound with the bullet hole present in the glass pane. FORENSIC SCIENCE: An Introduction by Richard Saferstein 8 8

GENERAL BLOODSTAIN FEATURES Bloodstain patterns deposited on floors, walls, bedding, and other relevant objects can provide valuable insights into events that occurred during the commission of a violent crime. FORENSIC SCIENCE: An Introduction by Richard Saferstein 9

GENERAL BLOODSTAIN FEATURES The crime scene investigator must remember that the location, distribution, and appearance of bloodstains and spatters may be useful for interpreting and reconstructing the events that produced the bleeding. FORENSIC SCIENCE: An Introduction by Richard Saferstein 10

GENERAL BLOODSTAIN FEATURES Bloodstain pattern interpretation may uncover: Ø The direction from which blood originated. Ø The angle at which a blood droplet struck a surface. Ø The location or position of a victim at the time a bloody wound was inflicted. FORENSIC SCIENCE: An Introduction by Richard Saferstein 11

GENERAL BLOODSTAIN FEATURES Bloodstain pattern interpretation may uncover: Ø The movement of a bleeding individual at the crime scene. Ø The approximate number of blows that struck a bleeding victim. Ø The approximate location of an individual delivering blows that produced a bloodstain pattern. FORENSIC SCIENCE: An Introduction by Richard Saferstein 12

EFFECTS OF SURFACE TEXTURE Surface texture and the stain’s shape , size , and location must be considered when determining a bloodstain’s direction, dropping distance, and angle of impact. Surface texture is of paramount importance. In general, the harder and less porous the surface, the less spatter results. FORENSIC SCIENCE: An Introduction by Richard Saferstein 13

Figure 4– 2 A A bloodstain from a single drop of blood that struck a glass surface after falling 24 inches. A. Y. Wonder FORENSIC SCIENCE: An Introduction by Richard Saferstein 14

Figure 4– 2 B A bloodstain from a single drop of blood that struck a cotton muslin sheet after falling 24 inches. A. Y. Wonder FORENSIC SCIENCE: An Introduction by Richard Saferstein 15

DIRECTIONALITY AND ANGLE OF IMPACT The direction of travel of blood striking an object may be discerned because the pointed end of a bloodstain always faces its direction of travel. FORENSIC SCIENCE: An Introduction by Richard Saferstein 16

DIRECTIONALITY AND ANGLE OF IMPACT The impact angle of blood on a flat surface can be determined by measuring the degree of circular distortion. At right angles, the blood drop is circular; as the angle decreases, the stain becomes elongated. FORENSIC SCIENCE: An Introduction by Richard Saferstein 17

Figure 4– 4 The higher pattern is of a single drop of human blood that fell 24 inches and struck hard, smooth cardboard at 50 degrees. On this drop, the collection of blood shows the direction. The lower pattern is of a single drop of human blood that fell 24 inches and struck hard, smooth cardboard at 15 degrees. On this drop, the tail shows the direction. A. Y. Wonder FORENSIC SCIENCE: An Introduction by Richard Saferstein 18

DIRECTIONALITY AND ANGLE OF IMPACT Mathematically, the angle of impact can be calculated by the equation and determining the inverse of Sine A: Sin A = Width of Blood Stain Length of Blood Stain FORENSIC SCIENCE: An Introduction by Richard Saferstein 19

IMPACT BLOODSTAIN SPATTERNS Impact spatter occurs when an object impacts a source of blood. Forward spatter is projected outward and away from the source. Back spatter , also known as blowback spatter, is projected backward from the source. FORENSIC SCIENCE: An Introduction by Richard Saferstein 20

DIRECTIONALITY AND ANGLE OF IMPACT The direction of travel of blood striking an object may be discerned because the pointed end of a bloodstain always faces its direction of travel. FORENSIC SCIENCE: An Introduction by Richard Saferstein 21

DIRECTIONALITY AND ANGLE OF IMPACT The impact angle of blood on a flat surface can be determined by measuring the degree of circular distortion. At right angles, the blood drop is circular; as the angle decreases, the stain becomes elongated. FORENSIC SCIENCE: An Introduction by Richard Saferstein 22

CLASSIFYING IMPACT SPATTER Using droplet size to classify impact patterns by velocity gives investigators insights into the general nature of a crime but cannot illuminate the specific events that produced the spattern. Low Velocity Spatter Ø Drops with diameters of 4 mm or more normally produced by an applied force of up to 5 ft. /sec. FORENSIC SCIENCE: An Introduction by Richard Saferstein 23

CLASSIFYING IMPACT SPATTER Medium Velocity Spatter Ø Drops with diameters from 1 -4 mm with an applied force of 5 to 25 ft. /sec. High Velocity Spatter Ø Drops with diameters of less than 1 mm from an applied force of 100 ft. /sec. or faster. FORENSIC SCIENCE: An Introduction by Richard Saferstein 24

CLASSIFYING IMPACT SPATTER The classifications of impact spatter as low, medium, and high velocity cannot illuminate the specific events that produced the stain size pattern. In general, one should use stain size categories very cautiously and for descriptive purposes only in evaluating impact spatterns. FORENSIC SCIENCE: An Introduction by Richard Saferstein 25

SOURCES OF BLOOD SPATTER Impact Spatter Cast-Off Spatter Arterial Spray Spatter FORENSIC SCIENCE: An Introduction by Richard Saferstein 26 26

Figure 4– 6 A The action associated with producing impact spatter. A. Y. Wonder FORENSIC SCIENCE: An Introduction by Richard Saferstein 27 27

Figure 4– 6 B The action associated with producing cast-off spatter. A. Y. Wonder FORENSIC SCIENCE: An Introduction by Richard Saferstein 28 28

Figure 4– 6 C The action associated with producing arterial spurt spatter. A. Y. Wonder FORENSIC SCIENCE: An Introduction by Richard Saferstein 29 29

AREA OF CONVERGENCE area of convergence The area of convergence is the point on a two-dimensional plane from which the drops in an impact pattern originated. This can be established by drawing straight lines through the long axis of several individual bloodstains, following the line of their tails. FORENSIC SCIENCE: An Introduction by Richard Saferstein 30

Figure 4– 7 An illustration of stain convergence on a two-dimensional plane. Convergence represents the area from which the stains emanated. The Institute of Applied Forensic Technology, Ocoee, Florida FORENSIC SCIENCE: An Introduction by Richard Saferstein 31

AREA OF ORIGIN The area of origin of an impact bloodstain pattern is the area in a three-dimensional space from which the blood was projected. This will show the position of the victim or suspect in space when the stain-producing event took place. FORENSIC SCIENCE: An Introduction by Richard Saferstein 32

AREA OF ORIGIN The string method is commonly used at a crime scene to approximate the position of the area of origin using found angles of impact of individual stains in the pattern. FORENSIC SCIENCE: An Introduction by Richard Saferstein 33

GUNSHOT SPATTER Gunshot spatter is fine forward spatter from an exit wound and back spatter from an entrance wound. The gunshot produces only back spatter if the bullet does not exit the body. FORENSIC SCIENCE: An Introduction by Richard Saferstein 34

GUNSHOT SPATTER Depending upon the distance from the victim that the gun was discharged, some back spatter may strike the gunman and enter the gun muzzle. This is called the drawback effect. FORENSIC SCIENCE: An Introduction by Richard Saferstein 35

CAST-OFF SPATTER A cast-off pattern is created when a blood-covered object flings blood in an arc onto a nearby surface. This kind of pattern is commonly produced by a bloody fist or weapon between delivering blows. FORENSIC SCIENCE: An Introduction by Richard Saferstein 36

CAST-OFF SPATTER The features of the cast-off pattern are affected by the size of the object, the amount of blood, and the direction the object was moving. By counting and pairing forward/backward patterns, one may determine the minimum number of blows delivered. FORENSIC SCIENCE: An Introduction by Richard Saferstein 37

ARTERIAL SPRAY SPATTER Arterial spray spatter is caused by an injury to the heart or a main artery and the pressure of the continued pumping. The site of the initial injury to the artery can be found where the pattern begins with the biggest spurt. The trail away from this point shows the victim’s movement. FORENSIC SCIENCE: An Introduction by Richard Saferstein 38

ARTERIAL SPRAY SPATTER The oxygenated blood spurting from the artery tends to be a brighter red color than blood expelled from impact wounds. FORENSIC SCIENCE: An Introduction by Richard Saferstein 39

Figure 4– 11 Arterial spray spatter found at a crime scene where a victim suffered injury to an artery. Norman Reeves, BPA Consulting, Tucson AZ www. bloody 1. com FORENSIC SCIENCE: An Introduction by Richard Saferstein 40

EXPIRATED BLOOD PATTERNS An expirated blood pattern is created by blood that is expelled from the mouth or nose from an internal injury. The presence of bubbles of oxygen in the drying drops, or a lighter color as a result of dilution by saliva, can differentiate a pattern created by expirated blood. FORENSIC SCIENCE: An Introduction by Richard Saferstein 41

EXPIRATED BLOOD PATTERNS The presence of expirated blood gives an important clue as to the injuries suffered and the events that took place at a crime scene. FORENSIC SCIENCE: An Introduction by Richard Saferstein 42

VOID PATTERNS A void is created when an object blocks the deposition of blood spatter onto a target surface or object, and the spatter is deposited onto the object or person instead. The blank space on the surface or object may give a clue as to the size and shape of the missing object or person. FORENSIC SCIENCE: An Introduction by Richard Saferstein 43

VOID PATTERNS Voids may be applicable for establishing the body position of the victim or assailant at the time of the incident. FORENSIC SCIENCE: An Introduction by Richard Saferstein 44

CONTACT/TRANSFER PATTERNS A contact or transfer pattern is created when an object with blood on it touches one that does not have blood on it. Simple transfer patterns are produced when the object makes contact with the surface and is removed without any movement of the object. FORENSIC SCIENCE: An Introduction by Richard Saferstein 45

CONTACT/TRANSFER PATTERNS The size and general shape of the object may be seen in a simple transfer. Other transfers, known as swipe patterns , may be caused by movement of the bloody object across a surface. FORENSIC SCIENCE: An Introduction by Richard Saferstein 46

Figure 4– 15 A series of swipe patterns moving from right to left. A. Y. Wonder FORENSIC SCIENCE: An Introduction by Richard Saferstein 47

FLOWS Flow patterns are made by drops or large amounts of blood flowing by the pull of gravity. The flow direction may show movements of objects or bodies while the flow was still in progress or after the blood dried. FORENSIC SCIENCE: An Introduction by Richard Saferstein 48

FLOWS Interruption of a flow pattern may indicate the sequence and passage of time between the flow and its interruption. FORENSIC SCIENCE: An Introduction by Richard Saferstein 49

POOLS A pool of blood occurs when blood collects in a level (not sloped) and undisturbed place. Blood that pools on an absorbent surface may be absorbed throughout the surface and diffuse, creating a pattern larger than the original pool. FORENSIC SCIENCE: An Introduction by Richard Saferstein 50

POOLS Considering the drying time of a blood pool can yield information about the timing of events that accompanied the incident. FORENSIC SCIENCE: An Introduction by Richard Saferstein 51

SKELETONIZATION The phenomenon of skeletonization occurs when the edges of a stain dry to the surface. This usually occurs within 50 seconds of deposition of droplets, and longer for larger volumes of blood. FORENSIC SCIENCE: An Introduction by Richard Saferstein 52

SKELETONIZATION After this time, if the bloodstain is altered through contact of a wiping motion, the skeletonized perimeter will be left intact. Knowing the skeletonization time, an investigator determine the timing of movement or activity. FORENSIC SCIENCE: An Introduction by Richard Saferstein 53

DROP TRAIL PATTERNS A drop trail pattern is a series of drops that are separate from other patterns, formed by blood dripping off an object or injury. The stains form a kind of line or path usually made by the suspect after injuring or killing the victim or injuring themselves. FORENSIC SCIENCE: An Introduction by Richard Saferstein 54

DROP TRAIL PATTERNS The pattern may show direction and speed of movement, lead to a discarded weapon, or provide identification of the suspect by his or her own blood. FORENSIC SCIENCE: An Introduction by Richard Saferstein 55

DOCUMENTING BLOODSTAIN EVIDENCE Investigators should note, study, and photograph each pattern and drop to record the location of specific patterns accurately and to distinguish the stains from which laboratory samples were taken. FORENSIC SCIENCE: An Introduction by Richard Saferstein 56

DOCUMENTING BLOODSTAIN EVIDENCE Two techniques used to document bloodstain patterns are: Grid Method Ø A grid of squares of known dimensions are set up over the entire pattern. Perimeter Ruler Method Ø A rectangular border of rulers is set up around each pattern and a smaller ruler is placed next to each stain. FORENSIC SCIENCE: An Introduction by Richard Saferstein 57

Figure 4– 19 The grid method may be used for photographing bloodstain pattern evidence. R. R. Ogle, Jr. , Crime Scene Investigation and Reconstruction, 3 rd ed. , Prentice Hall, Upper Saddle River, N. J. , 2011 FORENSIC SCIENCE: An Introduction by Richard Saferstein 58

Figure 4– 20 The perimeter ruler method may be used for photographing bloodstain pattern evidence. Courtesy Evident, Union Hall, VA 241764025 www. evidentcrimescene. com FORENSIC SCIENCE: An Introduction by Richard Saferstein 59

INTERPRETING BLOODSTAIN EVIDENCE Some jurisdictions have a specialist on staff who will decipher patterns either at the scene or from photographs at the lab. However, it is important that all personnel be familiar with patterns to record and document them properly for use in reconstruction. FORENSIC SCIENCE: An Introduction by Richard Saferstein 60