Chapter 12 Death: Manner, Mechanism, Cause

internal examination

1) Y-shaped incision from shoulder to shoulder meeting at breastbone + extending to public bone; ribcage cut 2) internal organs removed; arteries + veins cut + larynx + esophagus; internal organ mass removed 3) stomach contents removed 4) cut ear to ear across forehead → skull → opened → brain removed 5) tissue samples taken from organs (e.g. liver: poisoning) 6) organs examined for unusual appearance + trauma 7) body fluids (e.g. urine, blood, saliva, ocular fluid extracted, vaginal swab) 8) body prepared for funeral home + reports completed (6 hours)

external examination

1) dictation of information into recorder 2) body in sealed body bag or sealed evidence sheet → photographed + X-rayed before removal → checked for trace evidence (e.g. insect) 3) body temperature taken + observations of liver mortis + rigor mortis 4) position + presence of clothing + other items collected noted before removal (struggle?) 5) examined for evidence of injury + trace evidence removed 6) hands bagged (shooting or fighting) → swabbed for gunshot residue + tissue samples under fingernails - bags used preserved for evidence 7) examined under alternative light source → enhance visibility of secretions on body 8) wound examined before body cleaned + prepared for internal examination; wound measurements taken → identify weapon 9) body weighed, measured; sex, ethnic background, hair length + color, eye color, age recorded; identifying marks recorded: tattoos, body piercings; documented + photographed 10) fingerprints taken

states of decomposition

1) several hours after death (fresh; initial) - cell autolysis beings - muscle lose tone - bladder + rectum empty due to loss of muscle control - onset of algor, livor, rigor mortis - cloudy film forms over eye if left open - flies arrive to deposit eggs on body - body temperature drops 2) after several days (bloating; putrefaction) - blistering of skin + internal organs → skin slippage (easy separation of outer skin from underlying tissues) - putrefaction: destruction of soft tissues due to bacterial activity a. gases, seepage, changes in body color - abdominal swelling (anaerobic bacteria of intestines consume tissues + release carbon dioxide) - marbling (skin discoloration) because protein decomposition - sulfur compounds + hemoglobin → brown color to veins + skin (abdomen + spreads) - sulfurous odors - loss of rigor mortis - increased insect activity 3) days 7-23 (active decay; black putrefaction) - bloating: more gases (e.g. hydrogen sulfide, methane, sulfur dioxide, putrescine, cadaverine) released inside body - discoloration - ruptures in skin occurs → seepage of fluids into surrounding areas → increase bacterial + insect activity - soft tissues of body liquefy 4) after 3 weeks-2 months (advanced decay) - greatest loss of mass (insect infestation, bacteria, purging of fluids) - fats of body undergo decomposition → greasy wax (adipocere) a. moist conditions → bacterial action breaks down fats into greasy material that coat body b. prevents oxygen from getting to tissues = preserve 5) after 2 months (dry or skeletal) - soft tissues gone - bones remain - odors mostly gone

autolysis

breakdown of cells as they self-digest

decomposition

breakdown of once-living matter by living organisms

accidental death

caused by unplanned events - e.g. car accident, falling from roof

algor mortis

cooling of the body after death - take temperature → insert thermometer into liver o rectum - accurate for deaths that occur within past 24 hours if corpse not subject to unusual heat loss conditions - factors to consider: body temperature before death a. person had fever or heat stroke: body temperature higher than normal at death b. person in shock, had congestive heart failure, or blood loss: body temperature lower than normal at death - 1 hour after death: body cools at rate of 7.8°C (1.4°F) per hour - after first 12 hours: body cools 0.39°C (0.7°F) per hour until reaches same temperature of surrounding

homicidal death

death of one person intentionally caused by another person - e.g. beating, shooting, burning, drowning, strangulation, hanging, suffocation

putrefaction

destruction of soft tissue by bacteria that results in release of waste gases + fluids

cornoer

elected official, either layman or physician, who certifies deaths + can order additional investigations of suspicious deaths - identify body, notify family, collect + return personal items

death of individual body cells is __________ process that does not occur at exact moment heart or brain __________.

gradual; stops

cause of death

injury or condition responsible for person's death (heart attack, kidney failure) - reason someone dies - disease, physical injuries, stroke, poisoning, heart attack

natural death

interruption + failure of body functions resulting from age or disease - most common

autopsy

medical examination to determine the cause of death - require for deaths due to injury, poisoning, unusual infections, foul play - two types of autopsies: 1) clinical: medical research study purposes when foul play not considered; doctor or family may request to determine cause of death 2) forensic (medico-legal autopsy): when foul play suspected a. external examination: b. internal examination

suicidal death

occurs when person purposefully kills himself or herself

manner of death

one of five ways in which person's death classified (i.e. natural, accidental, suicidal, homicidal, or undetermined)

medical examiner

physician who performs autopsies, determines cause + manner of death, + oversees death investigations

livor mortis (death color)

pooling of blood in tissues after death that results in red skin color - area of pressure on body prohibit blood from settling + lack coloration - results when blood cells + blood vessels decompose: red blood cells contain hemoglobin (carries oxygen + red color) → autolysis: released from red blood cells + spills in blood vessels → break down → substance pools - lividity: reddish-purple color - 2 hours after death: lividity becomes noticeable - after 8 hours: discoloration permanent - death occurred between 2 + 8 hours: lividity present; if skin pressed → color disappears - after 8 hours: if skin pressed → lividity remains - effect of gravity on blood = reveals position of corpse during first 8 hours after death a. corpse on back with legs extended → back + back of arms + legs exhibit lividity - dual lividity: person found with lividity in two different areas a. evidence that body kept in one position for at least 2 hours + moved to second position before permanent

mechanism of death

specific physiological, physical, or chemical event that stops life - specific change in body that brought cessation of life - e.g. death is shooting a. mechanism of death = loss of blood - e.g. death is heart attack a. mechanism of death is heart ceasing to beat or cardiac arrest - e.g. death from "massive trauma to body leading to respiratory arrest" a. trauma: cause of death b. respiratory arrest: mechanism of death

17th century, before __________ invented, anyone in __________ or with weak __________ presumed dead and in danger of being buried.

stethoscope; coma; heartbeat

rigor mortis (death stiffness

stiffening of skeletal muscles after death - temporary - less than 2 hours: no visible rigor - 2 hours: rigor mortis becomes apparent - 2-6 hours: stiffness progresses form smaller muscle groups to large muscle groups (face, jaw, neck) - 12 hours: body in most rigid state - 15-36 hours: stiffness gradually disappears (cells break down during autolysis (rigor throughout body, lack of rigor in face, jaw, neck) - 36-48 hours: no visible igor - skeletal muscles unable to relax a. life: contracting + relaxing of muscles occurs as muscle fiber slides back + forth b. live muscles relax → release calcium c. no circulation after neath, muscles cannot get oxygen → calcium → accumulates in muscle tissue → remain rigid until autolysis of muscle cells occur d. muscle controls movements of bones → joints rigid

sequence of death

stoppage 1) heart stops → blood no longer pumped → delivery of oxygen glucose to cell stops → chemical + physical changes 2) lack of oxygen + glucose → less energy for cells - cells with greater reserves of oxygen glucose = survive longer 3) cellular respiration converts to anaerobic respiration (without oxygen) → less energy + build up of lactic acid 4) toxic waste accumulate → lowers pH of cells → cell membrane rupture → cytoplasm seeps out of cells autolysis (cell self-digestion) damaged or injured cells trigger autholysis (cellular demolition) → cellular enzymes released inside cell that break down cell contents + rupture cell membrane → destroy cell

postmortem interval (PMI)

time between death + body discovery - longer = less accurate

proximate cause of death

underlying cause of death, not final cause - e.g. person repeatedly kicked in kidneys during beating + dies of kidney failure a. proximate cause of death: beating

death

when enough individual cells die that heart or brain stops functioning - sequence of events that affect some cells sooner

stomach and intestinal contents

• 2-6 hours: stomach to empty contents into smaller intestine - undigested stomach contents present → death occurred between 2 + 6 hours after meal • 12 hours: food leave small intestine - stomach empty, food found in small intestine → death occurred at least between 6 + 12 hours • 24 hours: wastes released through rectum - small intestine empty + wastes found in large intestine → death occurred 12 or more hours after meal

rate of decomposition depends on

• age - young decompose faster than elderly • size of body - large deposits of fait + body fluids break down faster than bodies of average mass • nature of death - ill decompose faster than healthy • unclothed bodies decompose faster than clothes bodies • bodies decompose fastest 21-37°C (70-99°) temperature range - higher temperature with low humidity → dry out corpses = preserve - lower temperatures → prevent bacterial growth + slow decomposition - moist environment rich in oxygen → speeds up decomposition • decompose quickly in air + more slowly if buried

factors that affect when rigor mortis sets in and how long lasts

• ambient temperature: - cold: slower onset + slower progression of rigor - warm: faster onset + faster progression of rigor • person's weight - obese: fat stores oxygen → slows rigor - thin: body loses oxygen quickly → accelerates rigor • presence, absence, + weight of clothing • illness • level of physical activity shortly before death - anaerobic exercise: lack of oxygen to muscle, buildup of lactic acid, + higher body temperature → accelerates - sleep: fully oxygenated muscles exhibit rigor more slowly • exposure to heat, cold, sun, wind

variables affecting digestion

• amount, type, temperature of food • illness + stress - person under emotional stress: affect digestion

"rule of thumb" PMI estimate

• body feels warm + limp: dead less than 3 hours • body feels warm + stiff: dead 3-8 hours • body feels cold + stiff: dead 8-36 hours • body feels cold + limp (dead more than 36 hours)

factors affecting heat loss

• body surface area relative to mass: thin bodies lose heat faster than heavy bodies • body position: extended body presents greater surface area than curled-up body → loses heat more rapidly • clothing on body: clothes insulate body → reduces heat loss • retention of fluids: with congestive heart failure, body retains fluids; water has high specific heat → slows heat loss • colder environment: heat loss faster in cooler environments • windy area: heat loss faster due to better head conduction away from body • submerged bodies: heat loss faster if water cooler than body; water good conductor of heat - warmer water than body temperature (e.g. hot baths or tubs) → slow heat loss

variables that affect rate of lividity

• corpse left outside on hot day → livor mortis progress faster • body left in cool room → livor mortis progress more slowly • livor mortis may not develop at in person with anemia or experience loss of blood

postmortem change sin eye

• life: surface of eye kept most by blinking • death: surface of eye dries out • cloudy film within 2-3 hours if eyes open at death - 24 hours: eyes closed or covered at death • potassium accumulates inside eye • not reliable

Mysterious Deaths at The Fair

• manner of death: accidental • cause of death: food poisoning/water contamination • mechanism of death: kidney failure

forensic aspects of forensic autopsy

• wound examination → determine type of weapon • wound depth • path of bullet • nature, number, type of wounds (defensive or offensive) • bullet recovery to compare bullets test-fired from suspect's firearm • determination of cause of death