Chapter 1 Intro to Forensic Science

Chapter 1- Intro to Forensic Science Forensic- pertaining to, or connected with, courts of law or public debate Science- knowledge of the physical world gained through observation Forensic Science- the application of natural sciences to matters of law Fields of Forensic Science Odontology- dental, bite marks Anthropology- bones Toxicology- fluid or body tissue, DWI, Biology- other body fluids Chemistry- proving white powder is a drug Trace Analysis- glass, impression, hairs and fiber Ballistics- sworn officers who look at casings, bullets Impressions- usually under trace analysis Question Documents- looking at inks, forgeries Forensic Photography- pictures of all types of evidence Forensic Medicine started in 6th century China. 1880- Alphonse Bertillion developed first id called anthropometry 1887- Sir Arthur Conan Doyle uses scientific methods to aid his investigations 1892- Francis Galton does first extensive study of fingerprints 1901- Karl Landsteiner discovers four categories of blood 1910- Edmond Locard sets up first police lab in Europe. Locard Exchange Principle 1985- Sir Alec Jeffreys applied molecular biology to forensic science (DNA analysis) Federal Labs FBI, DEA, ATF, US Postal Inspection Service State Regional: NJ (E,S, Central Labs) Centralized: (CT, they have one forensic lab) Combination (NY) County Union County Prosecutor’s Office Westchester County Medical Examiner’s Office Forensic Scientist Functions -applies the principles and techniques of science to the analysis of evidence -must use the scientific method -observation (collection of data) -hypothesis (reasonable explanation of data) -testing (experiments to prove/ disprove hypothesis) -theory (verified hypothesis) Expert Witness -a person who can prove to a trial judge that they possess knowledge in a profession relevant to the trial, that isn’t expected of the average person -qualifying questions are asked to demonstrate the experts ability and competence pertaining to the case -opposing counsel can cross examine the expert to find weaknesses in their knowledge Expert v. Lay Witness Expert -called to evaluate evidence and give an opinion as to the significance of their results Lay -Can only testify on personal experience or knowledge on observation -Cannot express an opinion The Forensic Scientist -advocate for the truth -is unbiased -draws conclusion based only on the results obtained from evidence analysis sent to the laboratory Physical Evidence in the Courtroom -Frye Rule- 1923 Frye v. US (lie detector not admissible in DC Circuit Court) -court must decide if new procedures are generally accepted -Rule 702- a more flexible standard compared to Frye Rule, doesn’t rely on general acceptance (Strictly federal) -Daubert Rule- the rules of evidence assign to the trial judge the ultimate responsibility for the admissibility and validity of scientific evidence presented in their court Chapter 2 The Crime Scene -The crime scene is the most important and major source of physical evidence. -Each crime scene is unique. -never rush through the processing of a scene -if a mistake is made, there is no second chance -the search must include a wide area -some cases will have more evidence than others -Secure and protect the scene -render first aid -apprehend the perpetrator -call the crime scene unit, supervisors, ems -maintain control of and isolate the scene -do not do anything that may alter the scene -Sort the relevant items from the insignificant -Normal v. Abnormal Conditions -Mental Reconstructions -try out various scenarios in your head -human behavior differs from person to person -Photography -photograph scene in an unaltered condition -Overall Photographs-photographs of the entire scene and surrounding area/entry and exit points, and from different angles -also used to document the location of items and their relationship to each other for evidence -Close Up Photographs- used to record the details of a specific item -Sketches -document the layout and the relationship of objects to the scene -a sketch is a draft of all essential evidence, information, and measurements of scene -rough sketch -finished sketch- drawn with care, contains all information, used in court -Notes -general description of scene -personnel present, date and time -location and evidence -Video Camera -video documentation provides a way to produce an overall record of a scene -Audio Recording -allows investigators to document details when walking through a scene -Search for Evidence -must be thorough and systematic -must not overlook any potential evidence -what to look for is determined by the circumstances of the crime -Line Search, Grid Search, Zone Search -Collection of Evidence -physical evidence must be handled in a way that prevents any change from taking place -do not disturb evidence until it is fully documented -Packaging Evidence -protect and preserve evidence -PPE Personal Protective Equipment -hairnet,face mask, jumpsuit, gloves, booties -Problems found at crime scene -change in environment -potential for loss of control due to rioting or neighborhood unrest -contamination of evidence -Crime Scene Safety -be careful with syringes or sharp objects -Hepatitis is transmitted more readily and will last longer in dried stains than AIDS -use gloves and a mask Chapter 3 Physical Evidence 3 Main Types are blood, semen, and fibers Information from Physical Evidence -prove modus operandi (method of operation) -identify the subject -exonerate the innocent -establish linkage -suspect to victim -suspect or victim to scene Significance of Physical Evidence -identification -individualization (comparison) -reconstruction Identification -items are classified or categorized -identification is a requirement -requires using established tests that give the same results every time they are used Individualization -”Could this evidence come from a particular object or person?” -”Does this evidence eliminate the individual?” Comparison -subjects an unknown specimen and a specimen from a known source to the same tests to determine if they have a common origin -step 1 -select meaningful characteristics to test and subject both the unknown and the known to the same tests -step 2 -draw a conclusion about the origins of the specimen -render an opinion as to whether or not the unknown and the known have a common origin Individual Characteristics -evidence that can be associated with a common source, with an extremely high degree of certainty, is said to possess individual characteristics -fingerprints, bullets, toolmarks, footwear impressions Physical Match -glass or headlight in a hit and run Class Characteristics -evidence that can be associated only with a group and not a single source -paint, glass, fibers, soil Reconstruction -the process of determining how a crime may have occurred based on observation and the evaluation of physical evidence collected from the scene -main requirement for an accurate reconstruction is an undisturbed crime scene -position of the body location of bullets, presence of blood spatter, etc.,can help determine what occurred Radial Fractures -cracks that extend outward like the spokes of a wheel Concentric Fractures -cracks that form a rough circle around point of impact Chapter 8 The Microscope A Microscope is an optical instrument that uses a lens to magnify the fine details of an object The Magnifying Glass -the earliest and simplest microscope The magnified image is observed by looking through the lens -this image is known as a virtual image A Real Image can be seen directly, like the image that is projected onto a movie screen -you do not have to look through a lens to view the image The ordinary magnifying glass can magnify about 5 to 10 times the actual image The Compound Microscope -Mechanical System -supports the microscope -Optical System -illuminates the object Mechanical System -Base-the support upon which the instrument rests -Arm-supports the scope and acts as a handle for carrying -Stage-the plate on which the specimen is placed, the slide is held by spring clips -Body Tube-a hollow tube on which the objective and eyepiece are mounted. Light passed from one lens to another through this tube -Coarse Adjustment-used to focus the lenses on specimen by raising and lowering the body tube -Fine Adjustment-similar to the coarse adjustment, but fine tunes it Illuminator- the artificial light is supplied by a light bulb to illuminate the specimen Condenser- collects light rays from the base illuminator and concentrates them on the specimen Objective Lens- the lens closest to the specimen Eye Piece (Ocular Lens)- the lens closest to the eye Field of View- the area of the specimen that can be seen after its magnified The Comparison Microscope -two compound microscopes combined into one unit -uses a bridge with a series of mirrors and lenses to join two independent objective lenses into a single binocular unit -when you look through the eyepieces, a field, equally divided into two parts by a fine Line (generally used for ballistics, looking at bullet casings) -uses reflected illumination (light comes from top) The Scanning Electron Microscope (SEM) -forms an image by aiming a beam of electrons onto the specimen and studying the electron emissions Chapter 11: Hairs and FIbers Trace Evidence -human hair, animal hair, fibers, paint chips, soil, fingernail scrapings, glass fragments Locard Exchange Principle -anytime there is contact between two surfaces, there will be a mutual exchange of transfer or material Indications of Association -transfer of micro-environments with others Hair -people lose 100-200 hairs a day -as a result, its a very common type of physical evidence -hair is an appendage of the skin that grows out of an organ known as the hair follicle -once the hair reaches the skin surface, the cells making the hair are no longer living -Hair Shaft is composed of three layers -cuticle-outside covering of the hair, formed by overlapping scales that always point towards the tip end of each hair -scales of most animal hair look like shingles on a roof -because the scales of animal hair come in a variety of patterns, scale patterns are an important feature in species identification -not useful for individualizing human hair -cortex-inside the protective layer of the cuticle -embedded with pigment granules that give hair its colow -the color, shape, and distribution of these granules are important for id purposes -medulla- collection of cells that look like a central canal that runs thru center of Hair -not all hairs have medulla -degree of medullation -continuous ------interrupted - - - - -fragmented - -- - ---- - -- -absent -human hair is usually fragmented or absent -most animals are interrupted or continuous -medulla of a human is less than ⅓ -medulla of an animal is ½ or greater -root-hair goes through three distinct growth phases -anagen, catagen, and telogen -anagen-the follicle is actively producing hair -if hair was forcibly removed, follicular tissue would adhere to root Sheath -catagen- hair continues to grow but at a decreasing rate -root takes on an elongated appearance -can last 2 to 3 weeks -when hair hits this phase, pigment producing cells stop functioning -telogen-when hair has stopped growing and falls out of scalp easy -can last 2 to 6 months -root has club shape -Compound and comparison microscopes used to look at hair -What is being looked at? -color,root,cuticle,shaft diameter, tip, medulla, presence of physical damage -Species Identification -look at medulla and the cuticle -Age and sex cannot be determined by microscopic examination of hair -If follicular material is on the root, its possible to perform DNA analysis -Fibers -can be divided into two categories (Natural or Manufactured) -Natural-derived from animal or plant source (cashmere, wool, fur fibers/cotton) -Manufactured-derived from either natural or synthetic fibers -Regenerated Fibers- fibers from natural raw materials (rayon and acetate) -Synthetic Fibers- produced solely from synthetic materials (nylon, polyester,acrylic) -Microscopic Comparison -dye composition-most textile fibers are impregnated with a mixture of dyes to obtain a color or shade -Thin Layer Chromatography is a chemical test thats used to separate the dye components -Sample Collection-fibers are mass produced making them common and abundant -fiber evidence may only give class characteristics Chapter 12 Drugs Any natural or synthetic substances that are used to produce physiological or psychological effects. -otc, Rx, alcohol, nicotine, and any controlled substances Controlled Substances -drug or chemical whose manufacture, possession or use is regulated by a gov. -regulated because of the effects on the central nervous system Dependency -psychological- conditioned use of a drug caused by underlying emotional needs -arises from numerous personal and social factors -intensity of the psychological dependence depends on the nature of the drug -alcohol/cocaine/heroin/nicotine have a high degree -caffeine/codeine/marijuana low degree -physical dependence-changes on the users body that want you to continue using -if they stop taking the drug, they become ill -addiction Types -narcotics,hallucinogens, depressants, stimulants, club drugs -hallucinogens-marijuana -depressants-alcohol -stimulants-cocaine,crack -club drugs-GHB, MDMA, Ketamin Controlled Substances Act of 1970 -made 5 schedules of classifications for CDS Chapter 6 Fingerprints Ridge Characteristics -island, short ridge, ridge ending, bifurcation, enclosure -Its the identity, number, and relative location of these characteristics that impart individuality to a fingerprint A fingerprint will remain unchanged during an individuals lifetime Fingerprints are a reproduction of friction skin ridges Dermal Papillae-cells between the epidermis and dermis. -shape of this determines the pattern of the ridges of the skin Latent Fingerprints-prints deposited by the oil/sweat on fingers Fingerprints have general ridge patterns (Loop arch or whorl) Loops- Loop wraps to the thumb is Radial Loop. Ulnar Loop opens towards pinky Deltas-look like triangles Whorls- have two deltas Plain whorl- has one ridge that makes a complete circuit, in the form of a spiral Central pocket loop- has atleast one ridge that makes a complete circuit Double Loops- two loops combined into one fingerprint Accidental-contains two or more patterns or isnt covered by other categories Arches-ridge lines that enter from one side and flow out the other side -Plain Arch-ridges that rise like a wave -Tented Arch-ridges have a sharp spike Arches do not have lines, deltas, or cores AFIS/IAFIS-Automated Fingerprint Identification Systems Three kinds of crime scene prints -visible, plastic, latent -visible- made by fingers touching a surface after the ridges have been touched by blood, etc Chapter 4: Bloodstain Pattern Analysis Significance of the location, position and shape of bloodstain patterns -possible movement of people -positions of people -reconstruction of events -direction of where blood oriented Spatter Dynamics -result of a force interacting with a pool of blood -assumes a straight line trajectory -direction and angularity can be determined Determining Factors -texture of surface -direction of travel -impact angle Surface Texture -harder and less porous the surface, less spatter Satellite Spatter -when blood droplets strike another object or a pool of blood, resulting in a distribution of spatters around the parent stain Direction of Travel -can be determined by the stain’s shape -the pointed end faces in the shape of where it was traveling Impact Angle -determined by length and width of the stain An elongated shape impacts the surface at an angle that was less than 90* Chapter 9 Firearms, Tool Marks and Other Impressions Firearms- to determine whether a bullet or cartridge was fired by a particular weapon IBIS-Integrated Ballistic Identification System Chapter 15 Forensic Serology -the examination and analysis of biological evidence -The Study of Serum -Biological Evidence -blood, semen, urine, vaginal secretions, fecal matter, saliva, sweat, nasal mucus -Blood is divided into cellular and liquid portions -cellular contains red/white/platelets -Red Blood Cells(Erythrocytes) -200 million cells in a drop of blood -hemoglobin/to transport oxygen -White Blood Cells (Leukocytes) -each microliter of blood contains 4,000-10,000 white cells -fighting infections -Platelets(Thrombocytes) -blood clotting -Liquid Portion -plasma,contains nutrients, antibodies, and proteins