ch2NotesSDN (1)_compressed.pdf

# Chapter 2: Evidence ## Edmund Locard (1877-1966) * Known for Locard's Exchange Principle * "Every contact leaves a trace" * Explains how evidence is created and how it can be used to recreate an event * Contact or interaction between people gives evidence * Gives transfer evidenc...

# Chapter 2: Evidence ## Edmund Locard (1877-1966) * Known for Locard's Exchange Principle * "Every contact leaves a trace" * Explains how evidence is created and how it can be used to recreate an event * Contact or interaction between people gives evidence * Gives transfer evidence * Established his forensic lab in 1910 * Founded and directed the institution of criminalistics at the University of Lyon ## Evidence Types * **Inclusive** * Evidence that "answers" the question * **Indeterminate** * Evidence that doesn't help answer a question * **Exclusive** * Evidence that excludes a possibility * Like it eliminates a possible answer to the question ## Forms of Evidence * **Testimonial (eyewitness)** * Evidence recorded from a witness * **Physical** * Raw material that forensic scientists examine # Admissibility of Evidence * Whether or not evidence can be used in court depends on the courts application of the rules of evidence. * Law values precedent when determining admissibility. * The court needs to assure the methods used on the evidence are scientifically acceptable and reliable. ## Court Standards * These are standards that courts use to determine admissibility. * **Frye Standard (Frye vs. U.S.)** * Requires that scientific methods be generally acceptable to a significant proportion of the scientific discipline * **Federal Rules of Evidence & Daubert Standard** * More flexible guidelines * In 2016, 16% of states used Frye * 76% of states used Daubert * The rest used other standards. # Categories of Evidence * **Inculpatory or Exculpatory** * Includes or excludes a person as a source * **Direct or Circumstantial** * Direct evidence establishes information with no need for further inference * Circumstantial evidence serves as the basis from which additional info. can be inferred * Most evidence is circumstantial. # Methods of Interpretation * 3 Types * **Deductive** * AKA inference * Similar to mathematical reasoning * x = 1, y=1 → x=y * Drawing conclusions from facts * **Inductive** * Uses existing data to make predictions and generalizations. * **Abductive** * Most commonly used * Gathering what is known, and using it to come up with the simplest and most likely solution. # Chapter 3: Crime Scene Investigation. ## Crime Scenes * Any place, each scene is unique due to the unique chain of events that occur. * Crime Scenes are fragile and begin to change/decay from the moment they are created. * The biggest challenge in processing a crime scene is ensuring the evidence collected reflects what happened *during* the criminal act and *not* something from before or after. ## Forensic Scientist Go to Crime Scenes. * They actually mainly analyze the evidence given to them and generate reports. * The objective of a crime scene investigation is to recognize, preserve, and collect physical evidence. * One of the biggest challenges: determine what is relevant and what is not. ## Primary Crime Scene * Where the initial act occurred * Macro Crime Scene/Macroscene * Large scale * Secondary Scenes * Created by acts that follow the original crime * Micro Scene * Smaller parts of a scene * Ex: A specific room ## Initial Crime Scene Investigation * First responders complete initial work and ensure safety of everyone. * CSI (crime scene investigation) perform a preliminary scene survey/walk-through * Images and videos usually taken at this time * Will note if there are special considerations that need to be addressed * Ex: It's raining, outside evidence needs to be addressed * This establishes scope and how much area should be secured * Video recording is standard procedure * Biggest issue is with editing software, ex: Photoshop ## Crime Scene Documentation * Types of Coordinate Systems for Documentation * **Triangulation** * Points X and Y are fixed. * Evidence a and b are measured from point X and Y. * **Baseline** * Points X and Y are fixed. * Evidence a and b are measured along the line between X and Y. * **Polar Coordinates** * Object a is a distance from Wall X and is 30°SW. A transit or compass is used to measure the angles. ## Sketching the Crime Scene * The critical aspect is obtaining and recording accurate measurements * It is the assignment of units of measurement/correct perspective to the overall scene and the relevant evidence. * The reason to sketch, is to measure and locate objects in space. ## Forensic Mapping and Laser Scanning * We use digital imaging technology and GPS to make a crime scene map (possibly 3D) * Referred to as forensic mapping * 3D Forensic Mapping/Laser Scanning * 3D scanning and imaging combined with mapping tech * Based on LiDAR, includes using a laser, scanner, and a GPS device * Laser light pulses are sent out and reflected back to its detector, allows for 3D imaging. * Becoming standard practice. ## Crime Scene Search * Preliminary crime scene search is for obvious items of evidence, following this is documentation. * After documentation, but before packaging evidence, an intensive search for the less obvious or overlooked items begins ## Crime Scene Search Patterns * **No Pattern, just following evidence** * Typically used in smaller scenes (linkage easier to follow) or large outdoor scenes. * **Line/Strip Pattern** * Typically used in large outdoor scenes. * **Grid Pattern** * Typically used in large outdoor scenes * **Zone Pattern** * Typically used in scenes with defined zones. * **Wheel/Ray Pattern** * Typically used in small specialized scenes. * **Spiral Pattern** * Typically used in scenes with no physical barriers ## Documentation of evidence. * Marks the beginning of chain of custody procedures * Includes a form with identifiers, time and date of collection, number of objects, a basic description, and the name and signature the person collecting it ## Evidence Management Flowchart * Locate Evidence ⇒ Photo ⇒ Sketch * Deliver + Transfer Custody ⇒ Secure + Transport * Initiate chain of custody and document evidence # Chapter 5: Medico-legal Investigation of Death ## Investigation of Death * **Questionable Death (Equivocal Death)** * A death in which the circumstances or cause is not clear or obvious, requires additional investigation * **Death Investigation Systems** vary across the U.S. * Many jurisdictions have a medicolegal death investigator, who is the first investigative person to respond to a death scene. * **MDI** * Will focus on the body AND the scene * Will check for post-mortem changes * **Death Scene Investigation Flowchart** * Death Scene + 1st Responder ⇒ Death Investigator (Scene Response) ⇒ Autopsy (Post Mortem) ⇒ Toxicology/Physical Evidence (Investigation) ## Systems of Death Investigations * **Coroner** * A government agent with responsibility for death investigations * Sometimes required to have *medical training* * **Medical Examiner System** * Replacing coroners in some states. * Medical examiners (ME's) are licensed physicians with training in forensic pathology. ## Time, Manner, and Cause of Death * Cause and manner is required on death certificate. * **Cause of Death (COD)** whatever initiated the chain of events leading to death. ## Mechanism of Death * The biochemical or physiologic abnormality produced by the cause of death. * Injury trumps disease. ## Manner of Death * 4 Types (NASH) * **Natural** - Disease with no trauma. * **Accidental** - Involve trauma. * **Homicidal** * **Suicidal** ## Time of Death * Death is when the brain stops working. * Estimates of time of death are based on knowledge of post-mortem changes. * **Postmortem Interval:** time that has elapsed from death. ## 3 Key Changes After Death * **Rigor Mortis:** Stiffening of muscles after death (abt 4 hrs) (glycogen) * **Livor Mortis:** Discoloration of the body due to no blood circulation (develops abt 1 hr after) (disappears adot 36hrs) * **Algor Mortis:** Cooling of the body; general rule: a nude body in 18-20℃ drops 1.5℃ per hour, for the first 8 hours (normal body temp=37℃) ## Tools of Death Investigation * **Autopsy:** Dissection of a body to determine cause of death. * **Post-Medical History** * **Activities of Disease prior to death:** Provides context of death. * **Information from crime scene.** ## Autopsy Process * Removal of the internal organs of the chest, abdomen, and head. * Incision made from each shoulder to midline to pubic bone. * For brain: incision behind one ear to the other ear. * Reflection of scalp by peeling up and back, and then sawing the skull. * **Fixation:** Keeping an organ in formaldehyde to preserve it, by causing proteins to harden ## Traumatic Death * Death caused by trauma can be any manner ## Mechanical Trauma * When physical force of something exceeds the strength of the tissue affected. * Blunt objects cause lacerations. * Sharp objects cause incised wounds. * With firearm injuries: * Missing tissue is surrounded by white fragments of lead (lead snowstorm). * Unburnt powder that penetrates the skin produces stippling/tattooing around the direct injury. ## Asphyxia * When oxygen supply to the brain is shut off. * Possible causes: drowning, manual strangulation, strangling by ligature. * Often results in fracturing the hyoid bone * **Virtual autopsies** use noninvasive imaging methods to obtain the same info * They use X-rays, CTs, MRIs, etc. # Crime Scene Investigation and Evidence ## Crime Scene Investigation * The goal of CSI is to recognize, document, photograph, and collect evidence at a crime scene. * It is crucial that the CSI are there to secure the crime scene. * They are trained to recognize, document, and secure the crime scene. ## Guidelines for Evidence Acceptability and Expert Witness Testimony * Evidence must be sufficient and scientific using quantitative data. * Evidence must be reliable (consistent when retested) and valid (properly collected and analyzed.) * The SWG was formed in 2009 to revise and standardize protocols to improve evidence collection and testing. * Now it is the OSAC (Organization of Scientific Area Committees). ## Crime Scene Investigation Team * Police officers: Secure Scene and Direct Activity * Must know evidence collection * District Attorneys: Can be called to scene to determine if a search warrant is needed. * CSI * Medical Examiners: Determine Manner of Death (Natural, Accidental, homicide, suicide, undetermined). * Detectives: Interview Witnesses, CSI, and Specialists to obtain evidence to reconstruct the crime scene * Specialists: Examples are forensic anthropologist, botanist, etc. ## Locard's Principle of Exchange * First person to note this was Dr. Edmond Locard. * When 2 people come in contact with each other or an object, physical transfer occurs. * These transferred materials are called **Trace Evidence.** * Ex: Hair, fingerprints, soil, blood. * The intensity, duration, and nature of the entities in contact determine the extent of the transfer. * Ex: More transfer will happen in a fistfight than a handshake. ## Types of Evidence * **Direct Evidence:** Include firsthand observations such as eyewitness or police dashboard cams. * **Circumstantial Evidence:** Indirect evidence that can be used to imply a fact but doesn't prove it. * Ex: Finding a suspect's gun at the site of shooting. * **Circumstantial Evidence** * Physical * Ex: Fingerprints, glass, tire impressions, etc. * Biological * Ex: DNA in tissue, bodily fluids, hair, pollen, etc. * Trace * Reduce the suspect pool to a very small amount. * Usually with the exception of fingerprints reduce the suspect pool to a smaller amount. ## Evidence Can Also Be Class or Individual Evidence * **Class Evidence:** Narrows identify to a group of people * Ex: ABO blood sample excludes any other people with either other blood types * **Individual Evidence:** Narrows identify to a single person/thing * Ex: Fingerprints/DNA ## The Seven S of Crime Scene Investigation 1. **Securing the Scene:** * Safety of all individuals in the area is first priority and preservation of evidence is second * Protecting the area in which the crime scene has occurred and restricting all unauthorized people from entering. * The first responder keeps a security log and can ask for additional requirements, like experts. 2. **Separating the Witnesses:** * Avoiding collusion. * Witnesses will not to be able to talk to each other and CSI will compare witness accounts. * CSI will ask questions like: * When did the crime occur? * Who is the victim? * Where were you when you observed the crime scene, etc. 3. **Scanning the Scene:** * Forensic CSI need to scan the scene to determine where photos should be taken. * **Primary Crime Scene:** The location of the crime. * Ex: Robbery in store. * **Secondary Crime Scene:** Movement to a new location. * Ex: Suspect's home. 4. **Seeing the Scene:** * CSI needs to see the scene and photos of the overall area with/without measuring ruler should be taken. * **Triangulation:** Technique used to record evidence location from fixed reference points. 5. **Sketching the Scene:** * CSI make a sketch of the crime scene, all objects measured from 2 immovable land marks. 6. **Searching for Evidence:** * Single investigators might use gridded, linear; spiral patterns. * Groups of investigators might use linear, zone, quadrant patterns. * All evidence should be photographed/sketched/labeled/and documented. 7. **Securing the Evidence:** * Liquids and arson are stored in airtight, unbreakable containers. * Biological evidence are stored in breathable containers so that the evidence can’t dry out. * After it airdries, it's packed in a paper bundle - then placed in a plastic/paper container. * The container is sealed with tape and labeled with the signature of the collector written on the tape. * An evidence log and chain of custody document must be attached to evidence containers. * Control samples like hair, fiber, and blood must be obtained from the victim to eliminate some options. * **Chain of Custody:** * Individual finds evidence ⇒ Bagging in container ⇒ A person goes to the lab ⇒ Technician. * Technician after completing examination repackages the evidence and signs chain of custody log attached to packaging. # Mapping the Outdoor Crime Scene * **Datum Point** - Permanent, fixed Point of Reference. * Then locate and establish the north corner of the collection site: * Should be at least 1 meter from any evidence. * Its referenced from the fixed datum point using distance and angle. * This north corner is called the **Sub datum Point** * other corners of the collection site are marked based on the subdatum point ## Analyzing the Evidence * Evidence analysis can link a suspect, establish identity of victim/suspect, confirm verbal witness testimony, etc. * A Forensic Science Lab processes all of the evidence. * Forensic lab technicians are specialized and process *only one type of evidence.* * The Lead detective examines the evidence and checks the reliability of witness accounts! ## Process 1. Data Collection 2. Conjecture 3. Hypothesis formulation 4. Testing 5. Theory formulation ## Crime Scene Reconstruction * Involves forming a hypothesis of the sequence of the events from before a crime was committed. * Investigator looks at evidence and attempts to determine how it fits into the overall scenario. * Direct evidence more evidence than circumstantial evidence. * Some guidelines established by Department of Justice. * Experience of an investigator alone no longer establishes evidence validity. * Evidence is considered to be inclusive, exclusive, and inconclusive with respect to the suspect's guilt. ## Staged Crime Scenes * **Arson:** Perpetrator stages a fire to cover some other crime. * **Murder:** Staged to look like suicide; Victim is murdered and the perpetrator stages the scene to look like suicide. * **Burglary:** Burglary may be staged to collect insurance money ## Some Points to Consider a Staged Crime Scene: * All of the wounds on the victim consistent with the suspected weapon employed. * Could the wounds be easily self-inflicted, etc… ## Quizlet Info * **Macroscopic Crime Scene:** The broad crime scene/The larger setting in which a scene is found. * **Microscopic Crime Scene:** The smaller crime scenes in the broad crime scene. * **Corpus Delicti:** A crime must be proved to have occurred before a person can be convicted * **Modus Operandi:** Someone's habits of working; mode of operation. * **Walk-Through:** Preliminary Scene Inspection * **Type of Sketches:** Documenting crime scenes in sketches. 2 types - rough and finished sketches ## Coroner * **Coroner:** Government agent charged with responsibility for death investigations. * **Cause of Death:** The specific medical/physical reason that leads to death (GSW, stroke, cancer). * **Manner of Death:** The broader category/classification of how death occurred. * NASH: Natural, Accidental, Homicidal, Suicidal * **Mechanism of Death:** The physiological process by which death occurs. * Exsanguination, asphyxiation, organ failure. ## Rigor Mortis * Stiffening of muscles after death due to lack of ATP * It typically begins 2 hrs abt death, peaks at 12 hrs, dissipates within 48-72 hrs. * Influenced by temperature, physical condition, and environmental factors. ## Livor Mortis * Pooling of blood in lowest parts of body after death. * Distinctive discoloration (reddish/purplish) of skin. * It begins within 20 mins - 3 hrs postmortem, visible in areas of body closest to the ground. * Fixed about 6-12 hrs, blood in vessels start to settle and discoloration remains permanent. ## Algor Mortis * Cooling of body that occurs after death. * Typically a body's temp begins to fall about 1.5°-2°F (0.8℃) in the first few hours. * After 12 hours rate of temp slows down to 0.15°F or 0.3℃. ## Sudden Death * Death without any symptoms. * Death that occurs within a few hrs of the onset of symptoms. ## Incised Wounds * Wounds caused by a clean, sharp edged object like knife, razor, etc. ## Autopsy vs. Necropsy * Post-mortem examination of a human body or animal. ## Inframammary Incision * Incision made in the fold where the lower part of the breast meets the chest wall. ## Types of Mechanical Trauma * **Sharp Force:** Caused by sharp implements * **Blunt Force:** Caused by firearms. * **Lead Snowstorm:** White fragments of lead around the missing tissue. * **Penetrating GSW:** An entrance wound and no exit wound. * **Penetrating GSW:** An entrance and exit wound. * **Distance Determination:** Distance from the shooter to the victim. * **Contact/Near-Contact Wounds:** Wounds due to close range gunfight, suicide, execution. * **Carboxymyoglobin:** Compound formed from myoglobin on exposure to carbon monoxide. * **Stippling:** Pattern of tiny punctate abrasions, burns, etc. around GSW due to discharge of unburned/partially burned debris from firearm. ## Distant: * Any distance beyond that which produces stippling. ## Abraded * Scraped skin. ## Laceration * Caused by gunshot exit wounds. ## Hollow Point Bullets * Handgun bullets designed to enlarge their diameter during a passage through tissue. ## Asphyxia * Interruption of oxygenation of brain. ## Carbon Monoxide * Colorless, odorless, tasteless gas. * Toxic to hemoglobin in animals- interfering with blood to absorb O2. ## Contusion: * Accumulation of blood in tissues outside the blood vessels. ## Cyanide: * Consists of C, N and acts primarily on the enzymes of the mitochondria of the brain. ## Diatoms: * Small unicellular organisms found in most fresh and salt waters - Drowning - Found in bone marrow. ## Equivocal Death: * Manner of death is uncertain and open to multiple interpretations. ## Hematoma: * A blood tumor. ## Hyoid Bone: * Small horseshoe-shaped bone found in the neck, rear the base of the jaw. ## Ligature: * An object such as blue, rope, or cord that is wrapped around the throat to cause asphyxia. ## Naive Consumers: * Person who doesn't ingest large amounts of drugs/alcohol. ## Questionable Death: * Death that was not witnessed. ## Strap Muscles: * Muscles in the neck. ## Daubert Trilogy: * Judge becomes gatekeeper to determine admissibility of evidence. ## Contact Gunshot: * Leaves large lacerations, blackened skin, and carboxymyoglobin. ## Distant Gunshot: * Circular hole in skin, defective and abraded skin. ## Ventricular Fibrillation: * Quivering of the heart; caused by low voltage electricity. ## Tetany: * Sustained contraction of heart; caused by high voltage electricity. ## Manual vs. Ligature Strangulation: * **Manual:** * No fracture, only asphyxia and furrow on neck. * **Ligature:** * Fracture of thyroid cartilage, bruised strap muscles. ## Cadaveric Spasms: * Forceful muscle contraction at the moment of death. ## Autolysis: * When Internal Organs self-loosen after death. ## Adipocere: * Waxy, great fat that occurs when bodies are in water. * Macerated: Softening and breaking of skin from prolonged exposure to water. ## Arteriosclerosis: * Hardening of arteries. * Myocardial Infraction: Blockage of heart that results in death of heart muscle. * **Floater:** Decomposing body. ## Contusion: * A black and blue bruise. ## Marbling * Numerous veins beneath skin become visible and may show greenish discoloration. * Occurs 3-5 days after death and begins at the belly button # Importance of Examining Death * Job of the Coroner is to identify the body, notify family, collect and return personal items of deceased, and issue a death certificate. * If death is suspicious, the medical examiner consults with a forensic pathologist to determine presence/absence of disease, injury, or poisoning. * The medical examiner- medical doctor that oversees death investigation and performs autopsies to establish the cause, manner, and mechanism of death. * Forensic pathologists are trained in nonmedical sciences such as ballistics. ## The Science Of Death Examinations ### Manner of Death * 5 Manners of Death: Natural, Accidental, Suicidal, Homicidal, and Undetermined. * **Natural Death:** * Caused by interruptions and failure of body functions resulting from age, disease, or toxic exposure * **Accidental Death:** * Caused by unplanned events, such as a car accident or falling from a roof * **Suicide:** * Occurs when a person purposefully kills themselves * **Homicide:** * Death of one person caused by another person * Beating, Shooting, Burning, Drowning, Strangulation etc * Sometimes its determine if the manner of death was a suicide, accidental death, or a homicide ### Cause and Mechanism of Death * **Cause of Death:** * The reason someone dies. * Ex: Disease, Physical Injuries, Stroke, Poisoning etc. * **Proximal Cause of Death:** Underlying cause of death rather than final cause. * Ex: If a healthy person is repeatedly kicked in the kidneys during a beating, and soon dies due to kidney failure, the beating is the proximal cause * **Mechanism of Death:** * Specific Change in the body that brought about the cessation of life * Ex: If cause of death is shooting, mechanism of death is the loss of blood or loss of brain function ## Process of Death ### Stage 1: Stoppage * Heart Stops - Blood is no longer pumped - Delivery of oxygen is stop * Lack of food and oxygen ultimately leads to cell death. * Cellular Respirations becomes anaerobic respiration which leads to a buildup in lactic acid. * Toxic Wastes accumulate and the increased level of lactic acid lowers pH, leading to cell membranes rupturing and cytoplasm seeping ### Stage 2: Autolysis * Damage or injured cells trigger a cellular process known as autolysis (cellular demolition). * Cellular Enzymes are released inside the cell that break down the cell contents and rupture the cell membrane, destroying the cell. ## Characteristics of Death ### Algor Mortis * Cooling of the body following death. * Algor Mortis can be accurate for deaths that occurred within the past 24 hrs * Approx. 1 hr after death, the body cools at a rate of 0.78 degrees Celsius or 1.4 degrees Fahrenheit * After 12 hrs, the body cools about 0.39 degrees or 0.7 degrees fahrenheit until the body reaches the same temp as surroundings * Factors affecting heat loss: * Body Surface Area: Thin bodies lose heat faster. * Body Position: An extended body presents greater surface area then curled up body so it loses heat more readily * Submerged Bodies: Heat loss is faster if the water is cooler than the body. ### Livor Mortis * Results when blood cells settle due to force of gravity acting upon them, resulting in them pooling under the skin in thh lowest areas of the body. * The reddish-purple color that results is known as *lividity* * Areas of pressure on the body that prevent blood from settling will lack coloration. * Lividity becomes noticeable approximately after 2 hrs after death. * The Discoloration is permanent after 8 hrs, within 2 to 8 hrs, this coloration will disappear when skin is pressed, after 8 hrs, if the skin is pressed, the lividity is permanent. * On a hot day, livor mortis will progress faster and vice versa. * Livor Mortis might not develop if the person has anemia or who experienced a loss of blood due to injuries. * Lividity reveals position of a corpse. * If the corpse lay on back with extended legs, the back of the arms and the legs would exhibit lividity. * If a person was found in lividity in 2 different areas, this provides evidence that the body was kept in one position for at least 2 hours than moved to the second position before lividity became permanent. ### Rigor Mortis * Death Stiffness, its temporary and can provide evidence in estimating PMI. * It becomes apparent within 2 hours after death and the stiffness progresses from smaller muscle groups to larger muscle groups. * At 12 hours, the body is at its most rigid state. * At 36 hours, the stiffness gradually dips. * Depending on body weight and temp, rigor mortis can remain as long as 48 hrs * If the body has no visible rigor, it has been dead for less than 2 hrs or longer than 48 hrs. * If the body is very rigid, then the body has been dead for approximately 12 hrs. * If the body was exhibiting rigor only in the face, jaw, and neck, then the body has been dead for approximately 12 hrs. * If there is some rigor throughout the body, but a lack of rigor in the face, jaw, and neck, then the body is likely to * be losing rigor, and the death had occurred more than 15 hours ago. ### Postermortem Changes of the Eye * Following death, surface of the eye dries out, a cloudy film is observed within 2-3 hrs if the eyes were open and within 24 hours if the eyes were closed/covered. * The buildup of potassium can theoretically be used to estimate time of death. ## Decomposition Timeline 1. **Several Hours After Death:** * Cell autolysis begins. * Muscle loses tone. * Bladder and rectum may empty due to loss of muscle control. * Livor, Algor, and Rigor mortis starts * Flies arrive to deposit eggs 2. **Several Days After Death:** * Blistering of Skin, Putrefaction * Abdominal Swelling occurs, internal pressure from fluids may force fluids from body openings. * Skin Discoloration occurs as a result of protein decomposition and sulfur combines with hemoglobin for brown color in veins and skin * Lots of rigor mortis * Bloating continues, discoloration of skin may make identification of skin color impossible. * Ruptures in skin occur, leading to seepage of more fluids. * Soft Tissues of the body start to liquefy 3. **Days 7-23 after death: ** * Bloating continues, discoloration of skin may make identification of skin color impossible. * Ruptures in skin occur, leading to seepage of more fluids. * Soft Tissues of the body start to liquefy 4. **Three Weeks to 2 months after death:** * Greatest loss of mass occurs as a result of insect infestation. * The fats of the body start to undergo decomposition, forming a greasy wax called adipocere (preserves tissue). 5. **Two Months After Death:** * Soft Tissues are usually gone, so are odors, mostly bones remain. ## Rate of Decomposition * Unclothed bodies decompose faster than clothed bodies and bodies decompose fastest in the 21-37 degrees. * Higher temp with low humidity tend to dry out corpses and lower temperature tend to prevent bacterial growth and slow down decomposition. * Environments rich in oxygen speed up decomposition and decompose more quickly in air and more slowly in water. ## Rule of Thumb PMI: * Body feels warm and is limp (dead less than 3 hours.) * Body feels warm and is stiff (dead 3-8 hours.) * Body feels cold and is stiff (dead 8-36 hours). * Body feels cold and is limp (dead more than 36 hours). # Forensic Analysis of Death ## Autopsy * Medical exam performed by a medical examiner/ pathologist to determine cause, manner, and mechanism of death. * Provide Evidence to the deceased person's identity * Fingerprint and DNA analysis, hair analysis, physical and chemical examination etc. * 2 types: Clinical and Forensic * **Clinical Autopsies** are done for medical-research study purposes. * **Forensic Autopsy/Mediological Autopsy** done under state guidelines. * There is the External Examination and Internal Examination. ## PMI Estimates * **Nonbiological Time Indicators:** * Record of last cell phone use, times of unread emails, texts, voicemails. * Time of Bank and Credit Card Use * Watch broken ### Stomach and Intestinal Contents * It takes 2-6 hours for the stomach to empty its contents into the small intestine. * Takes another 12 hours for food to leave the small intestine. * Takes approx. 24 hrs from when a meal was eaten until wastes are released. * If undigested stomach contents are present, then death has occurred between 2 and 6 hours after the last meal. * If the stomach is empty but food is in the small intestine, then death has occurred at least between 6 and 12 hours after the last meal. * If the small intestine is empty and wastes are found in the large intestine, then death probably has occurred 12 or more hours after a meal. ### Entomology Reports * Insect development and succession are useful in estimating PMI ## Probable Cause of Death Analysis * **Examples are:** * **Drowning:** * Bloody froth from mouth and nose along with "washerwoman's skin" or shriveled skin due to submersion for several hours. * **Overdose of opioids or heroine:** * White foam in mouth and nose from fluid buildup in lungs (edema) * Cone of white foam forms under the mouth * **Strangulation:** * Petechial hemorrhages (red spots in white of the eyes) due to capillary rupture in blood vessels of the eye. * Broken hyoid bone - Circular Bruising and abrasions around the base of the neck * **Hanging:** * Abrasion and bruising forms in a V fashion under the chin from rope * **Carbon Monoxide Poisoning:** * Skin muscles, and lips have a bright red color. * **Alcoholism:** * Jaundice color of skin and yellow liver, bleeding in gastrointestinal area. * **Blunt Force Trauma:** * Blown pupil/ fully dilated pupil occurs on side of head where injury was sustained. * Bleeding under the membrane that surrounds the brain