Quiz 1 Material - Lecture notes 1-4 PDF

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intro to frsc
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Intro to Forensic Science What is forensics science?  The use of science to analyse evidence within a legal framework o Civil investigations o Criminal investigations  Includes areas of sciences and social sciences  Always associated with a crime o Not always a homicide Natural sciences vs. Forensic sciences  Natural sciences are said to be theoretical o Pure knowledge o Orderly, pristine, controlled, general, covering laws, predictions  Forensics sciences are said to be practical o Applied to problems o Disorderly, contaminated, chaotic, specific, approximations, conjectures Theoretical and forensics science  Logical methods characterize reliable scientific explanations in either theoretical or forensics contexts From crime to conviction  Ability to reason during times when human emotion may attempt to override rationality  Ability to be rational in applying tenets of forensics science to real life human situations  Ability to address life's grimmest realities while maintaining human feelings  Bound to combine scientific skills with a sworn duty to the public good Science and the law today  In law-a judge or jury determines the truth through their verdict  Science-is data based and founded on scientific methods  Science improves out understanding of the natural world  Depends on available evidence combined with reliable scientific methods  The scientific method has steps: o Formulate a hypothesis/a tentative explanation o Test with observations and experimentation o Revise the hypotheses based on results and REPEAT o Continue until the data are in agreement Modern practice of forensics science  There is no typical forensic science laboratory/workplace  The careers/jobs/workplace different and divers

Evidences in Forensics: Diversity and Admissibility Crime scene investigations  Linkage of persons, scenes, objects o Locard’s exchange principle  Provides investigative leads o Direct and indirect leads  Information on the modus operandi  Proving or disproving witness statements o Crime scene patterns or patterned physical evidence Locard’s principle  A cross transfer of evidence occurs between a criminal coming in contact with an object or a person  Enables the forensic scientist to determine the movements of the criminal based on trace evidence Bloodstain pattern evidence  Forensic tool  Used to: o Corroborate statements o Apprehend suspects o Interrogate suspects o Reconstruction of scene Death investigation  What is the main difference between a coroner and a medical examiner? o

Medical examiner system  Standards est. late 19th century  Prior to: no education or training required  1877: Massachusetts – replacement of coroner with licensed medical examiner  1914: urban areas followed suite (Baltimore, New York, Richmond)  Currently: rural areas retain elected coroner system Investigation of traumatic deaths  Investigate sudden and unexpected deaths of persons who are inapparent good health and deaths suspected to be traumatic  Traumatic deaths o Mechanical: sharp, blunt, firearm injury o Chemical: use of drug or poisons o Thermal: exposure to excessive heat or cold o Electrical o Asphyxias (deficient supply of oxygen) Forensic taphonomy  Forensic taphonomy is the study of the history of the body since death  Taphonomy is important because it may assist in: o Estimation of the time since death by observing post-mortem changes o Identification of the individual o Ability to determine cause and manner of death Forensic pathologist  Perform autopsies and diagnose circumstances surrounding the cause and manner of death

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Determine whether death was o Accidental o Suicidal o Homicidal Forensic anthropology  Defined as the application of the theory and methods of anthropology to forensic problems  Most forensic anthropologists have been specialists in physical anthropology, and particularly skeletal biology Forensic nursing  Forensic nurses assist in the medico legal investigation for victims of o Violence o Criminal activity o Traumatic accidents o Examples: rape, assaults, homicide  Provides direct and indirect services (individuals, agencies) in areas like o Evidence collection preservation and analysis o Questioned death investigation processes Forensic laboratory  Forensic lab has 2 purposes o Responsible for analysis of evidence o Involved in all aspects of evidence o Recognition, collection, and preservation  Must insure: o Law enforcement officers o Investigators o Attorneys o Judges and juries  Are educated in understanding the parameters which surround collection and testing of evidence  Physical science unit o incorporates the principles of chemistry, physics and geology to identify and compare physical evidence  Biology unit o Applies the knowledge of biological science in order to investigate blood samples body fluids, hair, and fiber samples  Firearms unit o Investigates discharged bullets, cartridge cases, shotgun shells, and ammunition  Document unit o Provides the skills needed for handwriting analysis and other questioned document issues  Photography unit o Applies specialized photographic techniques for recording and examining physical evidence  Some crime laboratories may offer the optional service such as:  Toxicology  Fingerprint analysis  Voiceprint analysis

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Evidence collection Polygraph administration

Forensic serology  The study of serology involves the examination and analysis blood and body fluids  Forensic serology deals with a variety of body fluids o Blood, saliva, semen, urine  Forensic serology also deals with samples that are in stain form often degraded or deteriorated Fingerprinting  Fingerprints are one of the oldest and most important evidence categories in forensic science  The use of individual friction ridge skin patterns on the end joint of fingers is centuries old  Fingerprint match is widely accepted as certain evidence of a particular person Class and individual characteristics  Forensic evidence arrives in court in one of two basic forms o Class characteristic – which do not reference a particular suspect  Individual characteristics – do associate a particular individual with commission of a crime Crime scene investigations  Linkage of persons, scenes, objects o Locard’s exchange principle  Provides investigative leads o Direct and indirect leads  Information on the modus operandi  Proving or disproving witness statements o Crime scene patterns or patterned physical evidence Locard’s principle  A cross transfer of evidence occurs between a criminal coming in contact with an object or a person  Enables the forensic scientist to determine the movements of the criminal based on trace evidence Bloodstain pattern evidence  Forensic tool  Used to: o Corroborate statements o Apprehend suspects o Interrogate suspects o Reconstruction of scene Death investigation  What is the main difference between a coroner and a medical examiner? o

Medical examiner system  Standards est. late 19th century  Prior to: no education or training required  1877: Massachusetts – replacement of coroner with licensed medical examiner  1914: urban areas followed suite (Baltimore, New York, Richmond)  Currently: rural areas retain elected coroner system Investigation of traumatic deaths  Investigate sudden and unexpected deaths of persons who are inapparent good health and deaths suspected to be traumatic

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Traumatic deaths o Mechanical: sharp, blunt, firearm injury o Chemical: use of drug or poisons o Thermal: exposure to excessive heat or cold o Electrical o Asphyxias (deficient supply of oxygen) Forensic taphonomy  Forensic taphonomy is the study of the history of the body since death  Taphonomy is important because it may assist in: o Estimation of the time since death by observing post-mortem changes o Identification of the individual o Ability to determine cause and manner of death Forensic pathologist  Perform autopsies and diagnose circumstances surrounding the cause and manner of death  Determine whether death was o Accidental o Suicidal o Homicidal Forensic anthropology  Defined as the application of the theory and methods of anthropology to forensic problems  Most forensic anthropologists have been specialists in physical anthropology, and particularly skeletal biology Forensic nursing  Forensic nurses assist in the medico legal investigation for victims of o Violence o Criminal activity o Traumatic accidents o Examples: rape, assaults, homicide  Provides direct and indirect services (individuals, agencies) in areas like o Evidence collection preservation and analysis o Questioned death investigation processes Forensic laboratory  Forensic lab has 2 purposes o Responsible for analysis of evidence o Involved in all aspects of evidence o Recognition, collection, and preservation  Must insure: o Law enforcement officers o Investigators o Attorneys o Judges and juries  Are educated in understanding the parameters which surround collection and testing of evidence  Physical science unit o incorporates the principles of chemistry, physics and geology to identify and compare physical evidence  Biology unit

o

Applies the knowledge of biological science in order to investigate blood samples body fluids, hair, and fiber samples  Firearms unit o Investigates discharged bullets, cartridge cases, shotgun shells, and ammunition  Document unit o Provides the skills needed for handwriting analysis and other questioned document issues  Photography unit o Applies specialized photographic techniques for recording and examining physical evidence  Some crime laboratories may offer the optional service such as:  Toxicology  Fingerprint analysis  Voiceprint analysis  Evidence collection  Polygraph administration Forensic serology  The study of serology involves the examination and analysis blood and body fluids  Forensic serology deals with a variety of body fluids o Blood, saliva, semen, urine  Forensic serology also deals with samples that are in stain form often degraded or deteriorated Fingerprinting  Fingerprints are one of the oldest and most important evidence categories in forensic science  The use of individual friction ridge skin patterns on the end joint of fingers is centuries old  Fingerprint match is widely accepted as certain evidence of a particular person Class and individual characteristics  Forensic evidence arrives in court in one of two basic forms o Class characteristic – which do not reference a particular suspect  Individual characteristics – do associate a particular individual with commission of a crime

Bloodstain Patterns Recognition of Bloodstain Patterns  Bloodstain pattern evidence  History of bloodstain pattern analysis  Properties of human blood  Formation of blood  Altered bloodstains  Analysis of bloodstains on clothing and footwear  Training and education Recognition of bloodstain patterns  Bloodstain pattern analysis assists investigators in better understanding what took place at a specific crime scene  It can assist with: o Corroboration of statement o Apprehension of a suspect o Interrogation of suspects o Reconstruction of past events  Strengths and weakness o Only as valid as information available and examiners abilities  History of bloodstain pattern analysis o 1895 Dr. Eduard Piotrowski  Published a book concerning direction and distribution of bloodstains following head blows o 1939 Dr. Victor Balthazard  Published "research on Blood spatter" o 1955 Dr. Paul Kirk  Submitted affidavit of his examination of bloodstain evidence and finding in state of Ohio v. Samuel Sheppard o 1971-73 Herbert Leon MacDonell  Conducted his first training program for blood spatter in Jackson Mississippi o 2002 SWGSTAIN  Scientific working group on blood stain  Pattern analysis -formed in 2002  www.swqstain.org  Active in developing and standardising blood stain pattern analysis  Most current terminology available at this website Properties of human blood  Biological o To tissues - oxygen, electrolytes, nourishment, hormones, vitamins, antibodies

o From tissue - waste products Plasma - fluid portion o Cellular components:  Red blood cells  White blood cells  Platelets  The fluid portion that doesn't clot is called serum  RBC o Hemoglobin o No nucleus  WBC o Nucleus o DNA  Healthy adults contain 4.5-6.0 liters  Blood is held together by strong cohesive molecular properties that create surface tension within each drop and on external surfaces o Surface tension of blood is slightly less than that of water  To create the spatter of blood: o An external force must overcome the surface tension of blood o The shape of the blood drop in sir is directly related to molecular cohesive forces  Cause the drop to assume the configuration of a spheroid  Volume: o Typical drop of blood has been reported to be .05ml with an average diameter of 4.56 mm  Viscosity o Mutual attraction of molecules of blood and the resistance to change of form or flow o Blood is six times more viscous than water  Specific gravity of blood is slightly higher than water  These properties tend to allow blood to remain stable and resist alteration or disruption Target surface considerations  Exposed blood has invisible outer skin referred to as surface tension  The external force don't overcome the surface tension of the blood  Blood will not break into smaller droplets or spatter unless an exterior force disrupts the surface tension  One factor may be the physical nature of the target surface  Hard, smooth surface, non porous surfaces (glass, smooth tile) create little if any spatter  Rough texture surface such as wood or concrete create significant spatter Size shape and directionality  Directionality o Direction of travel o Determined though geometry of stain  Edge characteristic o Narrow end = direction of travel  Area of convergence o Where lines converge o Represents the relative location of blood source in a two dimensional x and y axis  Area of origin 

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2D: long axes Draw straight lines though long axes where they converge is the relative source location  3D: impact angles  Establishes angles and project trajectories back to common axis 90° from the 2D area of convergence  Angle of impact o If 90° - resulting blood stain is circular o Lass than 90°  Elliptical o Width and length elliptical bloodstain allows for calculation of angle impact of origin blood drop o Width is divided by length to produce a ratio number less than 1  This ratio is sine of impact angle  Angle can be determined using a scientific calculator or sine function in tri table o Ratio: width/length  Circular → ratio = 1 → impact 90°  Elliptical → ratio > 1 → impact > 90°  Three dimensional origin o Stringing; placing elastic strings at the base of each blood stain and projecting back to the axis  Repeated for each selection blood stain 3-dimensional origin of pattern  Determined using projected strings and protractor to measure impact angles and determine height  Place elastic strings at the base of the selected stain and project along the z axis  automated digital methods  Concepts are still the same in both methods Spattered blood  Defined as a random distribution of blood stains that vary in size and that may be produced by a variety of mechanisms  To determine of an area or location of the origin of blood source and the specific mechanism by which pattern was created  If found on the person's clothing - place the person at the scene of violence altercation  The size, quantity and distribution of the spatter depends upon: o Quantity of blood subjected to impact o Force of the impact o Texture of the surface impacted by the blood  Spatter is created when sufficient force is avaiable to overcome surface tension of blood 

Categories of blood spatter based on the mechanism by which they are created Impact spatter  Associated with gunshot o Mist-like dispersion (less than .1mm) are associated with spatter associated with gunshot o May also be a wide size range from .1 mm up to several mm or more o Size range is dependent on:  Quantity of blood  Caliber of weapon  Location and number of shots  Impeding factors, such as hair and clothing o Forward spatter - associated with an exit wound o Back spatter or blowback - associated with entrance wound and may be found on shooter or weapon, especially hand and arm areas Horizontal perspective of back and forward spatter produced by gunshot

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Beating and Stabbing

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Generally exhibits a size range of 1-3mm Depends on force on impact and quantity of available blood First blow rarely produces spatter-exposed blood must receive impact Type of weapon and number of blows have effects on patterns Range of impact spatter  Size less than 1mm to 3mm is also commonly observed in cases involving  Gunshot, beating and stabbing and satellite spatter Secondary or satellite spatters  Resulting from dripped blood o Single drops of blood producing small spatters around parent stain as a result of striking a rough target surface - circular and oval, .1 to 1 mm o Drip patterns: multiple free - falling drops of blood produced from a stationary source onto a horizontal surface Projection spatter  Produced without an impact o Cast off  Patterns are created by subsequent blows to the same general area where a wound has occurred and blood has accumulated  Blood adheres to object producing injuries  Centrifugal force generated by swinging of weapon is great enough to overcome adhesive force of blood, thus creating a castoff bloodstain pattern o Arterial  Are scared by breaching of artery and subsequent gushing or spurting  Pattern depends on  Severity of injury to artery  Size and location of artery  Whether injury is covered by clothing  Position of victim at time of injury  Usually large quantity of bloodstains o Expirated  Expirated bloodstain patterns  Blood which accumulates in sinuses and airway passages is forcefully expelled  May appear diluted if mixed with saliva or nasal secretions  Air bubbles or vacuoles are not always present in this type of pattern  Splashed and projected blood stain pattern resulting from large volumes o Splashed bloodstain patter  A quantity of blood in excess of 1.0 ml  Allowed to freely fall onto a surface  Large central areas with peripheral spatters appearing as elongated blood stains o Projected bloodstain pattern  A quantity of blood in excess of 1.0ml  Projected downward onto a surface  Exhibits numerous spine line projections  Ex. Vomiting blood Other blood stain patterns  Blood transfer pattern

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Occurs when a object wet with blood comes into contact with an unstained object

Altered patterns o Subject to change due to quantity of blood present, and temperature, humidity and air currents  Skeletonized bloodstain  Occurs when central area of a partially dried bloodstain is altered by contact or wiping motion  Dried bloodstain  Age and go through colour changes  Red to reddish brown to black  Clotted blood stain  Clotting time assists in measuring amount of elapsed time since injury  Indicate additional activity such as movement or further injury, occurred after initial bloodshed  Void areas or patterns  Absence of bloodstain in otherwise continuous patterns of staining  Due to items removed from an area  Used to recognize the general location where the spatter event occurred Interpretation of bloodstains on clothing and footwear  Two questions arise with bloodstained garments o Whos blood and how was blood deposited on garment  DNA technology has assisted in identification of whose blood is present  Two categories o Passive bloodstaining  Transfer, flow patterns, saturation stains, and stains from dripping blood o Active bloodstaining  Impact spatter, arterial spurts, Expirated bloodstains, and castoff Luminol for bloodstain pattern analysis  Luminol is a chemiluminescent reagent that can be utilized as a presumptive test for blood  A method of chemical enhancement of impression in blood on various surfaces  Used to check ...