anth 245 exam two

entomology

the study of insects

insect basics

* estimated at 5.5 million species, quintillion bugs on earth (19 0’s)


* invertebrates
* cold-blooded
* exoskeleton
* 3 body regions (head, thorax, abdomen)
* 3 pairs of legs
* most have 2 sets of wings

exoskeleton

* hampers growth, overcome through metamorphosis
* bugs: egg → nymph → adult
* the body is generally similar, just sheds the skin and grows bigger (i.e: grasshopper)
* flies: egg → larva → pupa → adult (flies)
* body changes with each stage (i.e: caterpillar to butterfly), they look much different in each stage

forensic entomology

the study of insects applied to medicolegal circumstances

modern forensic entomology

* studies the insect matter, growth patterns, and succession of arrival at a crime scene to determine the time since death
* can approximate how long a body has been left exposed by examining the stage of development of fly larvae on the body
* insects are responsible for eating the most biomass

necrophagous insects

* carrion eaters (can detect carrion in unites, will find the body if accessible)
* eat 90% of the carcass, everything but the skeleton
* two main types: diptera (flies) and coleoptera (beetles)

diptera (flies)

use sense of smell to find decaying flesh, as far away

* blow flies, flesh flies
* early arrivers
* common
* food source: decaying flesh

coleoptera (beetles)

sharp mouth parts allow them eat what’s left, aka the skeleton/mummified flesh

* comes weeks after death
* food source: dried flesh, ligaments, larval flies
* feed along underside of body

other insects

* wasps & ants: feed off carcass and fly/maggot mass
* mites & moths: consume hair

\

the blow fly: eggs

* laid by females in open moist orifices (mouth, eye, ears, nose) and wounds within minutes of death
* even before death if the individual is unable to swat it away
* 2-3 mm long
* hatch after 1-2 days

the blow fly: larvae

* “maggots”
* three stages: 1st, 2nd, 3rd instars
* feed at carcass as a group (maggot mass) from egg site
* raking mouthparts (two hooks) that consume the flesh
* breathing and feeding parts on opposites ends of body, 24-hr feed
* post-feeding larvae: last period of 3rd instar
* 12mm long, 10x its original size, 8-12 days into the lifecycle
* migrate away from carcass → find a dark place to hide

the blow fly: pupae

* 9mm long, 18-24 days into life cycle
* living pupa inside of a pupal case and adult fly emerges from case
* empty cases stay for years
* find the oldest cases throughout the corpse and soil, these will indicate the PMI

the blow fly: adult

* emerge 20 or more days after egg
* mate, females lay \~100 eggs each
* feed from carcass, live 1-3 weeks

using flies to estimate TSD

* evaluate oldest stage of blow fly present and determine species/rate of development
* determine temperature of scene
* insects are cold-blooded so development is directly related to temperature (higher temp =quicker development)
* rates of development for species of blow flies and flesh flies based on temperature known
* if you know species, rate of development, and temp info, it can determine when egg was laid based on what stage of fly is present (not when murder occurred, just when individual was dead)

bugs in the field

* collect live and preserved eggs and larvae for analysis
* collect 100-200 larvae; focus on largest
* et some grow to confirm species
* collect live pupae and empty pupal casings
* collect live adults if they have just emerged
* also collect other insects (e.g. beetles)
* collection done with aerial nets, tweezers, brushes
* specimens placed in vials of preservative or rearing chambers
* temperature collection
* at scene: air, ground, body, soil, maggot mass
* later obtain temp info from nearby weather station
* soil collection: might contain smaller insects

using flies to determine TSD

the forensic entomologist analyzes collections (preserved) and rears live specimens to determine the species and stage present. then they analyze temp info and calculate TSD based on “energy units” necessary for each stage of lifecycle

limitations to using flies to determine TSD

it can only give a minimum TSD, also need to have thorough, accurate collection

* depends on season
* they need to know temperature info and other variables (ie: if body was wrapped or buried)

where forensic entomology helps

* can sometimes determine if body was moved
* some species are geography/location sensitive
* pupae cases remain for years and should be at body location

how forensic entomology helps

* fly colonization patterns can be used to indicate wound sites in decomposed bodies
* maggots and beetles can be tested for alcohol, drugs, and toxins
* can detect child/elderly person neglect

blunt force trauma (BFT)

injury caused by a blunt object or collision with a blunt object (like the ground)

* four types:
* contusions
* abrasions
* lacerations
* fractures
* most cases involve multiple manifestations of these types of trauma

principles of BFT that govern damage

1. amount of force applied
2. velocity of strike
3. area of distribution of strike on body
4. nature of weapon; if it can deform or not
5. nature of body area struck

BFT: contusions

rupture of blood vessels with blood loss into surrounding tissues (aka bruises)

* skin is unbroken, can be patterned or not
* lack of a contusion does not necessarily mean a lack

of trauma to that area

BFT: abrasions

superficial removal of epidermis, scrape caused by rubbing against a blunt object

* antemortem: reddish brown
* postmortem: yellowish and translucent

abrasions: scrape

blunt object scrapes off layers of skin

* ie: road rash

abrasions: impact

crushing by a blunt object

* can be patterned
* focal, commonly seen where a thin layer covers bone

BFT: lacerations

tissues tear due to crushing or shearing force, the wound is longer than it is deeper

* tissue bridging: little lines of connective tissue hold the skin together across the cut
* morphology may not be representative of the object

lacerations: perpendicular blows

crushing blows from a hammer, a fall to the ground, or boxing

lacerations: glancing blows

blow at an angle which may create gaping wounds

* can determine the directionality of the blow

lacerations: avulsion

skin and soft tissue are ripped off the bone

BFT: fractures

bones can withstand a greater load if applied at a slow velocity over a large area, but deformation depends on how fast the load is applied and for how long, and also the properties of the bone

* types:
* compression: squished from top to bottom
* tension: pulled from top to bottom
* shear: left and right pushed away from each other
* torsion: twisting from left to right
* bending: folded from top to bottom

stress-strain curve

bone reacts to a slow-loading stress (trauma) by straining (bending)

* elastic: deforms but bounces back
* plastic: deformation so great it can’t bounce back

long bone fractures

bone is stronger in compression than tension, so will fail in tension first

* can see direction of force

skull fractures

* the skull reacts somewhat differently than long bones to blunt force trauma due to its structure
* inbending at site of impact


* outbending adjacent to impact: linear and concentric fractures
* purpose of fracture lines is to distribute stress
* radiating fracture lines first, then concentric lines
* fracture lines do not cross, so can attempt to reconstruct chronology of blows

coup and contrecoup Injuries

* occurs when impact from an object or a violent motion brings head to a sudden stop


* brain damage caused by brain bouncing back and forth inside of skull
* coup: brain contusion at site of impact
* contrecoup: contusion on opposite side of brain
* can be more severe

defense wounds

contusions, abrasions, lacerations, and fractures that occur on the back of arms and hands to ward off blows

sharp force trauma (SFT)

blunt force with a sharp instrument (ie: knives, swords, axes). if it can penetrate the skin, not much can stop it except bone

* four types:
* incised
* stab
* chop
* therapeutic

SFT: incised wounds

cuts or slashes, **the length of the wound along the skin is greater than the depth into the skin**

* no tissue bridging, rarely fatal unless in a vital area (wrist, throat, femoral artery)

SFT: stab wounds

**wound depth in the skin is greater than the wound width across the skin**, usually homicidal (unlikely caused by accident)

* can tell single-edge blade or double-edged blade by wound ends:
* one cutting surface will create one blunt angle and one sharp angle
* two cutting surfaces will create two sharp angles

SFT: chop wounds

caused by heavy instruments with a cutting edge (ie: meat cleavers, machetes)

* combo of BFT & SFT
* wound often wedge-shaped, may be patterned, often have abraded margins
* can be an accident, homicide, or postmortem dismemberments

SFT: therapeutic

wounds made by medical personnel (ie: chest tubes, abdominal drains, tracheotomies)

* may occlude/alter pre-existing wounds

SFT to bones

incised: slices bone, cause long V-shaped scratches

stab: cuts bone

chop: crushes and cuts bone

wound morphology

depends on:

* condition of knife


* movement of people
* resistance of skin, organs, tissues
* presence and type of clothing

langer’s lines

patterns of elastic fibers in the skin that can cause differences between gaping wounds (if trauma is perpendicular) and slit-like wounds (if trauma is parallel)

* wound may not be the same size as the weapon that made it:
* movement can cause wound to be larger
* elasticity of skin can cause wound to be smaller

SFT & mode of death

most deaths from SFT are homicides, accidental SFT is rare. homicidal wounds are typically to the chest & abdomen

* suicidal wounds: absence of defense wounds

gunshot trauma (GST)

high velocity trauma, involving a projectile

* bone acts as brittle material due to high velocity
* stress-strain curve does not apply, no elastic/plastic deformation

BFT vs GST

* BFT is considered slow velocity trauma because blunt objects crush but do not typically penetrate soft tissue and bone. only creates one wound
* GST is considered high velocity trauma because it penetrates skin/bone at a fast speed. creates an entrance and exit wound

gunshot wounds (GSW)

* wounding power corresponds to the kinetic energy dissipated during deceleration through the target
* quicker loss of velocity means greater damage
* severity of wound depends on the amount of kinetic energy lost in the tissue
* mechanism of wounding is the creation of temporary and permanent cavities inside the tissues

GSW: temporary cavity

tunneling of bullet in tissue with tissue expansion on each side leading to massive tearing of immediate and remote tissues

GSW: permanent cavity

wound track that remains in tissues after temporary cavity has disappeared

examination of GSW

* soft tissue characteristics:
* determine trajectory of fire
* determine range of fire
* bone characteristics
* determine trajectory of fire
* determine number and sequence of wounds
* fracture lines do not cross!!!
* wounding potential: determined by loss of kinetic energy

GSW: entrance wounds (skin)

* small, round hole; creates abrasion
* soot and other material present based on distance to gun
* small amount of blood

GSW: entrance wounds (bone)

* creates cone-shaped defect (internal beveling)


* creates radiating fractures

GSW: exit wounds (bone)

* reverse cone from entrance wound such that beveling is now on external surface


* radiating fractures from entrance wound may beat bullet to opposite side

GSW: exit wounds (skin)

* more massive and irregular than entrance wounds
* the skin rips
* excessive blood and tissue loss

GSW: range of fire

distance between gun’s muzzle and victim’s injury

* examine pattern and density of smoke, soot, and gunpowder on skin
* as distance increases, lose flame, then smoke, then soot, then powder
* 3 primary categories:
* contact
* intermediate
* distant

GSW: contact wounds

* hard contact: muzzle held tightly against skin
* laceration of wound edges over bone
* smooth circular defect over soft tissue
* muzzle imprint
* soot and powder in wound tract


* loose contact: muzzle held lightly against skin
* charring of wound margin
* corona of soot around wound
* soot and powder in wound track

GSW: intermediate wounds

* tattooing
* abrasions or contusions due to burning powder
* doesn’t wash off
* soot and powder on skin

GSW: distant wounds

* no tattooing or soot deposition
* only bullet reaches victim
* opposite of contact GSW

GSW: problems in determining range of fire

* decomposed body (soot, tattooing all on skin, so if skin is decomposed, this evidence is lost)
* short-term survival after injury (hospital cleans wound)
* intermediate targets (cars, ricochet, re-entry)

GSW: caliber determination

highly unreliable from wound morphology, skin is too elastic and bone defect also to a good predicator

GSW: direction of fire

determined from spatial (straight-line) relationship of entrance and exit wounds

* three dimensions:
* anterior to posterior
* right to left
* superior to inferior

GSW: mode of death

* homicide, suicide, accidental all possible
* evaluation of range of fire & trajectory and location of entrance wound


* position of gun and body/lethal area of body


* GSR on the hand
* multiple bullet wounds/shotgun wounds do not rule out suicide
* “accidental” rests on investigation

multidisciplinary applications of forensic science

* local cases: forensic scientists work within their specialty but are always part of a larger investigative system
* global applications: going out of the lab comfort zone into dangerous situations, mostly post-conflict/event

mass disasters

sudden, unexpected events that cause extreme destruction and loss (also cause social and economic disruption)

* four types:
* natural
* transportation
* technological
* intentional

mass fatality incident

large-scale disasters that result in significant loss of life, one more death than local authorities can handle

* relative, non-static number
* requires multidisciplinary assistance

mass disaster response needs

* rescue
* relief
* rebuilding
* recover and ID of the dead

DMORT & its functions

defined: Disaster Mortuary Operational Response Team functions:

* assistance in search and recovery
* mobile morgue: can be anywhere in country in 24 hours
* victim ID
* family assistance center: antemortem data collection


* support personnel for DMORT team members is very diverse

natural disasters

* caused by the effects of natural phenomena that produces great loss of human life
* loss of infrastructure (medical, police, legal, electrical, water)
* homelessness, displacement, and loss of life
* disconnection of surviving family members, red cross and other groups assist in helping families reunite
* forensic roles:
* search/recovery of dead
* documentation (ID) of the dead

transportation disasters

* airplane, train, boat/ferry, bus


* nature of event and number of individuals killed determines response needed
* direct impact is local, family impact can be global


* Forensic roles:
* search/recovery
* ID of dead
* repatriation (return of someone to their own country)
* investigate the cause of accident
* testify at hearings/trials

technological disasters

structural failures, nuclear meltdowns (ie: bridge collapsing or power plant exploding)

* forensic roles:
* search/recovery
* ID of dead
* investigation of causes

intentional disasters

bombings, hijackings, rampages with a gun

* forensic roles:
* search/recovery
* law enforcement scene investigation, protection
* ID of dead
* full medico-legal investigations of the dead
* ID perpetrator(s)
* testify at hearings/trials

human rights investigations (HRI)

* application of forensic approaches to locate, recover, and ID victims of forced disappearance, genocide, crimes against humanity, and other war crimes (multidisciplinary)
* structural violence: violence toward a particular group of people is culturally acceptable (i.e. holocaust)

HRI goals

* justice: use physical evidence to bring those who committed atrocities to trial


* repatriation: provide families with knowledge of what happened to their loved ones

HRI procedures

* locate the bodies
* analyze written, oral sources
* if possible, use aerial photography to visualize soil disturbances
* indicators of soil disturbance
* excavate the graves
* document, photograph, map every layer
* look for evidence of violence (e.g. bullets, ligatures, etc)
* properly package and transport the remains

HRI lab work

* cleaning of remains & document all skeletal and personal effects
* MNI?
* biological profile (demography of the mass grave)


* identification of remains
* analysis of trauma
* antemortem can aid in identification
* perimortem can reveal cause of death

human dentition

32 adult teeth: 2 incisors, 1 canine, 2 premolars, and 3 molar (2:1:2:3) per quadrant

* deciduous dentition: smaller, lacks premolars and 3rd molars

tooth anatomy

* formation and development: heavily controlled by genetics
* does not change form (except chemical or mechanical damage)


* blood supply
* multiple tissues

human dentition: modifications/damage

* caries (cavities), likely no access to dental care


* periodontal (gum) disease (gum disease)
* impactions
* amalgams (regular fillings)
* crowns
* root canal fillings

forensic odontology

* combination of the science and art of dentistry and the legal system – the crossroads of dental science and law
* subdisciplines include:
* dental identification
* MFI
* abuse
* age estimation
* expert testimony in criminal or civil litigation
* bitemark analysis

dental identification

* person identified by dental records
* postmortem dental records of remains from unidentified person with antemortem radiographs of a known individual
* records include photographs, radiographs, dental charts
* can be complex depending on the state of remains

MFI and teeth

* dental records are collected from the victims for ID
* conditions depend on the event
* coordination of local personnel and specialists to collect information
* collection of antemortem victim data from family or databases

abuse

* extraoral injuries: beyond mouth/teeth


* intraoral injuries: tissue damage within the mouth
* higher incidence of carious lesions could be neglect

age estimation

* teeth are indicators of age, especially less than 21yr
* evaluation of:
* tooth development and eruption (x-rays, observations)
* tooth degradation/attrition (x-rays, observations)
* measuring biochemical & trace element changes in dental changes (specialized procedures, tissue destruction)

expert testimony

* forensic odontologists are often called up to give testimony as experts and can give opinions, should be impartial, thorough, accurate

dental comparisons

comparing antemortem records to the teeth from the remains

* dental radiographs are the preferred method


* they compare:
* number, spacing, shape of teeth
* location and type of restorations
* pathologies

statistical comparisons

* OdontoSearch: statistical tooth that quantifies the uniqueness of observed dental characteristics
* enter in a code for each tooth that corresponds to a certain location and type of modification


* OdontoSearch 1.0 looked at almost 40,000 dental records from WWII, Korea, Vietnam, and modern military, and modern civilians
* OdontoSearch 3.2 looks at modern military and civilians
* this dataset consists of 107,002 individuals over the age of 14, all anatomized

dental comparisons advantages

* teeth survive time, pH, burning, trampling, and some cremations (e.g. if done in a backyard, not industrial)
* different components of teeth can be very unique
* most people in the U.S. do have dental records; the military requires them

dental comparisons disadvantages

* no “magic number” of matches
* antemortem dental data can be unavailable
* dentists throw out charts over time and individual may have never visited the dentist


* lack of standardization of methods
* some records less detailed than others
* written records might have errors
* temporal changes
* teeth may have changed since last visit

bite mark analysis

* patterned skin injuries produced by teeth
* associated with violent crimes
* sexual assault
* child abuse
* homicide
* domestic violence
* holds potential to ID the perpetrator

steps of bite mark analysis

* recognize as a bite mark


* accurate documentation and collection
* swab immediately for saliva/DNA
* close-up photography with scales and an alternative light source, impressions
* compare to teeth of alleged perpetrator
* must work quickly (bite marks heal over time or can degrade)

bite mark analysis depend on

* presence of clothing
* movement of people
* location of bite (fleshy skin or not)
* amount of healing or decomposition since wound was inflicted
* age/skin color of victim

controversy of bite mark analysis

* no standards, rules, or regulations
* skin does not typically record the details of each tooth
* distortion of bite mark often occurs due to the many factors that affect a bite mark’s appearance
* misidentifications are much too common
* a 1999 study by a member of the American Board of Forensic Odontology found that 63% of certified dentists gave false positives
* **has yet to be validated!!!!**

forensic odontologist as a career

* application of dental knowledge to legal issues


* primary roles:
* personal ID
* perpetrator ID via bite marks
* analysis of facial injury and dental malpractice
* testimony

mechanics of fingerprints

* friction ridge skin=skin with series of ridges and grooves
* provides a non-skidding surface
* strengthened by manual labor
* forms in fetuses in approximately the 13th week fo development

fingerprints are…

1. UNIQUE: after initial pattern formation, grows randomly until completely formed
2. PERMANENT: once formed, retains exact structure unless injured


1. burns and extremely deep cuts can affect them
3. uniqueness and permanence basis for usefulness in identification (no two fingerprints the same)

types of fingerprints

1. loops: 60 to 65%
2. whorls: 30 to 35%
3. arches: 5%

fingerprints: loops

* ridge lines enter from one side of the pattern, curve around, and exit from the same side
* two types of loops:
* ulnar – ridges flow towards the little finger

(ridges flow towards the ulna)
* radial – ridges flow towards the thumb (towards the radius)
* requirements of a loop:
* sufficient recurve
* core: the approximate center of the loop
* delta: the point on a ridge at or nearest to the point of divergence of two lines

fingerprints: whorls

a class of fingerprints that includes ridge patterns that are generally rounded or circular in shape and have two deltas

* four types:


1. plain whorl
2. double loop whorl
3. central pocket loop whorl
4. accidental whorl

fingerprints: arches

a class of fingerprints characterized by ridge lines that enter the print from one side, make a rise or curve in the center, and flow out the other side

* two types:


1. plain arch
2. tented arch

friction ridges within patterns

* within the patterns, the ridges do not simply flow across in continuous line


* in addition to cores and deltas there are:
* bifurcations/forks
* trifurcations
* abruptly ending ridges
* crossover ridges
* islands in ridges
* spur or hook
* enclosure or lake
* these characteristics of the friction ridges are referred to as Galton details, aka minutiae