Forensic Pathology - postmortem investigation of sudden or unexpected death or trauma to the living Greek: pathos – disease logos – study of Pathologist is a medical doctor (10-15 post secondary training), detective, public relations – much time spent communicating findings to law enforcement officers and/or jury

Role of the Forensic Pathologist 4 broad determinations to be made: Cause of Death – medical diagnosis (the injury) Mechanism of Death –how the injury produced death (arrhythmia, exsanguination) Manner of Death 1. Homicide 2. Suicide 3. Accidental 4. Natural Causes D. Time of Death Cause of Death - Proximate cause of death – initial injury that leads to sequence of events which cause death - Immediate cause of death – injury/disease that finally kills person Example: Man burned in house fire dies weeks later due to sepsis (infection) proximate: burns immediate: sepsis B. Cause could be gunshot wound, Mechanism might be blood loss C. 2. Suicide – not always easy (hanging with erotic literature), insurance does not pay so recorded manner of death is important 3. Accidental – may involve human negligence 4. Natural – disease or old age

Time of Death Can estimate time of death from body changes estimate: [98.6 oF – rectal temp]/1.5 insect action (forensic entomology) stomach contents (stage of digestion) last known activity (last sighting, newspaper/mail)

The Body Farm 1 acre of land owned by the University of Tennessee

Normal Postmortem Changes Algor mortis: body cooling Rigor mortis: body stiffening Livor mortis: (lividity) blood settling Putrefaction: destruction of body tissue by bacteria

Algor mortis Cooling of the body after death. Best indicator of TOD in 1st 24 hrs Taken: Rectal Liver

Algor mortis Body cools approx 1.5 degrees C/hr Skinny cools faster No clothes cools faster In water cools much faster normal temp–measured temp/ 1.5 = # hrs

Rigor Mortis Rigor: stiffening of muscles due to build up of salts. Begins: 12 hours post mortem face, arms, abdomen, legs Takes: 12 hours to get fully stiffened Then starts to go away in same order Face, arms, abdomen, legs

Rigor Begins: 12 hours post mortem face, arms, abdomen, legs Takes: 12 hours to get fully stiffened Then starts to go away in same order Face, arms, abdomen, legs

Rigor Mortis Body warm not stiff less than 3 hours Stiffening of muscles seconds or minutes after death Rigor mortis results when [ATP] concentrations fall ATP = relaxed muscles Rigor mortis stops when muscles begin to decompose ~ 36 hours after death Body warm not stiff less than 3 hours Body warm stiff 3-8 hours Body cool stiff 8-36 hours Body cool not stiff more than 36 hours

Livor Mortis Lividity: red/purple coloration of skin. Due to settling of blood after death Skin will appear white in areas that were compressed.

Lividity will appear in about 2 hours. Areas will turn white if you press Lividity will be “set” after 5 hours

Normal Postmortem Changes Algor Mortis Rigor mortis Livor mortis Putrefaction Desiccation – mucous membranes (lips, eyes) shrivel and look darkly colored - time depends on location of the body, environmental conditions Putrefaction – (A) greenish discoloration of skin (B) growth of bacteria unchecked by immune system causes gas production which may swell, rupture organs or make soft tissue appear swollen - time again depends on environment of body (few days to weeks if colder) Autolysis – cells begin to break open and ooze contents - liquefaction of soft tissues Proteins break down into amino acids which are further degraded by bacteria into “biogenic amines” - this is what smells (putrescine, cadaverine)

Decomposition 2 days post mortem Marbling neck and shoulders 1st red then green From bacteria getting into subQ tissue bloating from gases created by bact. Organs decompose in order: Stomach and intestines, heart and liver Musculature

Trauma to the Human Body Role of the Pathologist Determine type of wound Measure the dimensions (length, width, depth) Position relative to anatomical landmarks Determine initial location if wound involves cutting, slashing, etc. Determine height from heel We said role of pathologist is to determine cause of death, extent of injuries to living, disease vs. poisoning, possible time of action: To determine these, pathologist will perform an autopsy (we’ll look at this in a couple minutes) First lets look at common types of trauma often encountered Why a pathologist looks at trauma above….

Types of Wounds (Trauma) Lacerations Incised Wound Puncture Abrasion Contusion Gunshot

Lacerations Tearing injury due to friction or impact with blunt object Edges are ragged, bruised, abraded

Incised Wounds Slash Stab Incised Wounds Cutting injury associated with a blade having smooth edges Slash – longer than it is deep Stab – depth greater than length Puncture Penetrating injury due to pointed object with no blade – icepick, pencil, etc

Abrasions Abrasion Friction injury removing skin or tissue

Contusions Color changes a bruise goes through can give rough estimate of time of injury Dark blue/purple (1-18 hours) Blue/brown (~1 to 2days) Green (~ 2 to 3 days) Yellow (~3 to 7 days) Assumes person is healthy. Contusions Bruise due to rupture of small blood vessels (skin or internal organs) Colors result from breakdown of hemoglobin from tissues

Stab Wounds Laceration is a tearing injury due to friction or impact with a blunt object. Puncture is a penetrating injury due to pointed object without a blade, such as an ice pick Serrated blades produce the same smooth edges as nonserrated blades. Abrasion is a friction injury removing superficial layers of skin, Contusion is a bruise due to rupture of small blood vessels. Slash wounds tend to look like bullet wounds that only graze the surface of the skin. Other types of slash wounds are called "hesitation marks" commonly found in suicide cases. They are typically rectangular in shape; i.e., their cuts are as wide and they are long. Incision wounds: cutting with a blade, always have lengths greater than their depth

Gunshot Wounds Things for pathologist to learn: type of firearm distance of gun to victim entrance vs exit wounds track of projectile Track of projectile – cause of death (hit certain organs?), location of shooter

Gunshot Wounds Stippling – powder burns on the skin when the gun is inches to a few feet from the victim Track of projectile – cause of death (hit certain organs?), location of shooter Starring of a contact wound – barrel touching the skin

Gunshot wounds Contact Wound: Muzzle applied to skin at shooting. Impression of muzzle burned around entrance wound Close Range (6-8 inches): Stippling Intermediate Range (1- 3 ft.): hot fragments of burning gunpowder; “ball” Distant (greater than 3 ft.): No soot or burning of wound margins Entrance wound: surrounding skin dragged in Exit wound: skin pushed out

Close range Close Range (6-8 inches): Entrance surrounded by stippling- HOT soot traveling for short distance; BURNS

Intermediate range Intermediate range 1-3 feet Gunpowder “ball”

POISONING Determined by discolorations on body Cherry- red lividity is sign of carbon monoxide poisoning Toxins give off unusual odors Certainty of diagnosis requires toxicological confirmation Samples taken of stomach, vomit, kidney, lungs, liver

BURN Wounds caused by heat, chemicals, or electricity Scorching or burning of skin leads to sepsis and is immediate cause of death Wounds caused by heat, chemicals, or electricity Fire victims found in “pugilistic” position: clenched fists, resembling pose of boxer Heat causes protein in body to contract Blood and lung samples taken

Blunt force trauma Blunt Force trauma results from clubbing, kicking, or hitting the victims. The blow produces a crushing effect on the human body, resulting in contusions, abrasions, lacerations, fractures, or rupture of vital organs. Red-blue contusions are always present, but this varies by the weight of the individual (obese people bruise easier than lean people)