ASM 275: Forensic Anthropology Exam 3 Study Guide You should concentrate on obvious definitions: Trauma
ASM 275: Forensic Anthropology
Exam 3 Study Guide
You should concentrate on obvious definitions:
Trauma• Any damage caused to the living tissue caused by an outside force• Can be used to determine the cause and manner of death
o Projectile trauma (bullets, arrows, spears)o Blunt force trauma – force applied to body over relatively wide
area(clubs, bats)o Sharp force trauma force applied to body over very narrow area
(knives, swords) 5 Contribution of trauma analysis to investigations
1. trauma at time of death (TOD) speaks to cause, manner of death2. force that caused the traumaID the murder weapon3. number of wounds single vs double, multiple4. determine the sequence of wounds determine sequence of events at the crime
scene5. determine the placement of wounds relationship between person causing wounds
and decendentCause of death: process that causes you to stop breathing and heart to stop beating (disease, trauma, starvation, old age)Manner of death the way the person died (homicide, suicide, accident, natural, unknown)Fracture vs infraction
• Fracture: when bone is broken completely into pieces • Infraction: incomplete bone breakage
Fracture: Completely broken, boney callous produced
Infraction called a hinge, break not completely broken apart though
Basic Bone Trauma• Displacements bone surfaces no longer meet, complete fracture• Hinge fracture incomplete separation, perimortem trauma (around time of death)• Greenstick fracture incomplete separation, subadults, not a complete clean break
(breaking a living branch)• Simple vs comminuted fracture
o Simple: a single discontinuity results, one bone broken to become 2o Comminuted: the bone shatters into many pieces, force involved is much
greater• Fracture displacements vs FRACTURE LINE
o Secondary fractures associated with primary traumatic event
Bat hits head: have fracture caused by bat hitting the skull (primary fracture), with great enough force has force that radiates out to cause fracture lines
o Radiating fracture lines most common, radiate out from impact areao Hoop fracture lines high velocity projectile wounds cause concentric
rings to form, in and out of beveling forces, force that travels out in all directions from impact sight
Displacement : red lines show break/original surfaces, red arrow is direction of force; large callous grown
Hinge fracture of cranium caused by blunt force trauma, tell tale sign of fresh injuries
Greenstick infraction
Traumatic comminuted fibula fracture; white arrow shows piece of lead; person never went to dr.
1 shows sword wound, 2 shows secondary fracture associated with action of sword being pulled out; no signs of healing so it killed individual
Radiating fractures: red arrows are secondary fracture lines from battle axe; some healing occured
Bullet hole exit wound causing hoop fracture; red arrow shows hinge, chipped fracture associated with bullet exiting skull creating concentric ring around exit wound
Fatigue or stress fractures, result from too much force applied to body over fairly long period of timeTrauma was a cumulative force, not distinct force
Depression fractures can be caused by breakdown of body over very long period of time, or dynamic compressive forceIf knees are brought up to face from result of fall, some of vertebral bodies can collapse
Stress fractures associated with occupation slay shovelers; white arrows show where spinus process broke off of back of vertebrae , in lower neck region, damage associated with that sort of occupational activity.
Fracture from result of practicing archery in European populations; act of pulling back strong draw string
Incredibly important to determine when the trauma occurred (before, close to, after time of death)
Characteristic of Forces Causing Trauma1. Direction of Force
a. Direction of force applied causes characteristic fracture types and patternsb. Relationship between body and outside force
2. Speed of force: 2 different classesa. Dynamic sudden stress, clearly defined most common, sharp force, blunt
force, GSW, most common for for. Anth.b. Static slow application of force rare strangulation, can result in fracture
of hyoid bone
3. Focus of Forcea. Size of area of primary force: area of impact on body
i. Narrow single point or thin line pointed or sharp instrument (sharp force trauma)
ii. Wide large bone area covered, large blunt object (blunt force trauma)
Timing of Bone Injury
• Antemortem injury happened before deatho Types of injuries you can link to medical records to make identification
• Perimortem injury happened near time of deatho More interesting in for. Anth, can speak to cause and manner of deatho Reconstruct death
• Postmortem there is no injury, the bone breakage occurred after deatho Force imparted on body is taphonomic caused in burial environment, or
something perp did to bodyo Doesn’t contribute to forensic analysis, just don’t want to mistake
postmortem broken bone for ante/perimortem
1. Tension: bone segments pulled apart result in fracture typical of accidents, lots of force pulling bones apart to cause them to break6. Compression: when bone segments are pushed together; blunt force trauma2&3. Torsion or spiral fracture: one half of bone stays still while other turns; typical of car accidents in particular7. Bending: similar to tension, but relationship
between direction is different
Colles Fracture of Distal Radius: typical of fallsWhen you fall, natural tendency to put arm out to brace yourselfGround acts as outside force that impacts body (though you are the one moving towards the ground)Can understand relation between ground and position while falling
Primary Fractures of Distal Ulna: defensive wounds (on left side of picture)Normal response to put arm in front of face to protect yourselfResults in fractures of distal ulna (exposed to attack)
Antemortem Trauma and Bone Fractures• Requires knowledge of bone healing process• 3 Phases of fracture healing
1. Hematoma forms bruising, blood pools over surface internal scab to help stabilize break, initial response
2. Callus formation woven bone deposited, poor evolutionarily not very advanced type of bone for stabilization
3. Remodeling woven bone replaced by mature bone
Fractured humerus; picture on left shows callus (darker area of bone); white arrow points to fracture line
Area around fracture (xray) is white= dense Dark= not dense
Fracture that is well healed, woven bone replaced by mature bone; textured of fractured area on top portion is pretty similar, happened long ago
How to Identify Antemortem Trauma• Process of bone healing should be present
o Increased porosity (holes) of bone near break while actively healing/remodeling
o Rounding of broken edges (<1 week)o Callus presence (6 weeks+)
• Remodeling (years, can sometimes never fully heal, never set by dr, callus may never go away)
Well healed femur fracture Well healed femur fracture, but never set; considerably displaced, will never fully heal
Cranial vault from someone who was scalped and lived; active signs of healing; holes are porosity of healing
Showing scalping line, lived for fairly long “antemortem” because they still never died
Perimortem Trauma and Bone Fractures• No signs of healing• Green bone (very fresh, alive) response 5 characteristics
1. Sharp edges of fracture and lines, no porosity2. Hinging on infractions not seen in postmortem fractures, lots of
collagen in bones3. Fracture Lines4. Angled broken ends5. Hematoma staining
Gun shot wound clean and crisp edges
Hinging, most likely caused by machete
Fracture Lines, probably due to brunt force traima
Angled fracture ends, look sort of like lightening bolts, irregularly shaped, no signs of healingprobably from car crash
Scalped but did NOT live, cut marks indicated by white arrows, no signs of healing; person died pretty quickly after
Also has fracture lines on side, piece missing on right probably killed from blunt object
Postmortem Bone Fracture• Not related to death, occurs after death• “Dry stick” type breaking• Features:
o Do not have fracture lineso Green stick and hinge fractures absent (bone drier, loses elasticity)o Breaks occur at right angles to long axis bone shaft
Blunt Force Trauma:
• Occurs any time a force impacts tissue over a relatively wide area• Includes some basic types of injury
o Blunt instruments (crowbars, baseball bats, bricks, pieces of lumber)o Car/train/airplane crashes (ground is source of trauma for plane crashes)o Abrasions of all kinds (including “road rash”)o Biteso Falls
Types of objects Characteristics of instruments: if can infer, may be able to generate profile of murder
weapon• Size of weapon
o Width of area between the contusions generally corresponds with width of weapon
Long axis (length): can sometimes estimate from dimensions of injury
Short axis (width): an object with small width needs less force to cause injury than broader one
o Easier to see in soft tissue, not so much in skeletonized remains Length is almost impossible to ID in skeletonized individual Width perhaps but also unlikely More likely to state whether force was focused or diffused Small width less force to cause serious damage, therefore some
estimate of size is necessaryo Pooling of blood and contusions, can make inference of size of object
can get width
• Shape of weapono Want to asses the cross sectional and longitudinal dimensions of weapon
Round: clubs, baseball bats, glass bottles Angular: some crowbars (hexagonal in cross section), lumber, etc.
• More likely to leave distinct makeso Act like blunt and sharp force object b/c of sharp
edge• Distinct edges• Fewer fracture lines• Most likely to leave imprint of shape on bone
• two impact sites, both angled• hit at maximum curvature site
• driven into skull• lack of porosity, no clean edges, lack of rounding, hinging
on impact site= perimortem with no signs of healing• Weight of weapon
o Heavier it is, greater force that can be imparted on body Obv, 12 oz can of coup cause less damage than 4lb baseball bat Heavy instruments can cause catastrophic features resulting in
large wounds with extensive crushing and fragmentation That 12 oz soup can could still cause injury just as fatal if hurled
with sufficient force Force of impact more important than weight of object used
o impact site near front of head, lots of damage probably heavy object like brick or piece of wood
Laceration, contusion, abrasion: soft tissue damage
• Laceration tear in skin caused by blunt instrument. NOT the same thing as a cuto Ex bleeding from being punched in MMAo Rip or tear, can be distinguished from a sharpforce injury with some ease,
although on gross examination will appear similaro Lacerations often have contusions (bruises); cuts not typically seen in cuts,
strings of flesho
• Contusion bruiseo Almost always blunt forceo Bruise color changes over time
Light bluish to dark purple then green, then yellow, then brown Can help tell difference between ante and perimortem May not be immediately apparent on initial examination, may
become readily observable some hours or days later
• Abrasion superficial scraping and/or stretching beyond its elastic capabilitieso Scraping or removal of superficial/top layers of skin
o Road rash body dragged along paved areao Stretching abrasion caused by stretching of skin beyond elastic tolerance,
often seen in road accidentso
Effects of Blunt Instruments on the Skull• Youthful, elastic bone deforms inwardly at point of impact
o Outer table is under compression while inner table under tension (being pulled apart)
• Bone more susceptible to tensiono Blunt force trauma causing breaks on inside of skull, more severe than
outside of skull esp in young individuals (elastic)• Bone breaks from inner surface out• Most trauma to skull because its easier to kill someone by smashing their head• Relationship between hitting rounded shape of skull and force applied to body•
o bone breaks more easily on inside under tension
•
o problem with diploe (inner spongey bone) can get simply crushed in, special case
o weak inner table special case• Buttressing and Force
o Four main buttresses (strong points) of cranial fault Midoccipital (back) Posterior temporal (behind ear) Anterior temporal (above eye) Midfrontal (middle of forehead) Force from blow to vault will cause fractures between these
buttresses
• Blunt Trauma to the Face
o Bones of face actually have regions of buttressing that guide the dissipation of force
o Bone areas surrounding buttresses are weaker and thus more prone to fracture
o Face breaks often conform to wellknown patterns called LeFort Fractures. There are 3 classical varieties
Will break in predictable ways Lefort 1 (gray band)
• Force applied to lower portion of face• Paired maxilla shatters straight across, separation from rest
of cranium• Separates upper teeth and alveolar bone from rest of skull
Lefort II• Midface separates from rest of cranium (teeth, nose, inner
portion of eyes break)• Caused by anterior blow to midface
• Lefort III
• Separates face from cranial vault• Caused by a centrally focused blow to upper face, middle
of eyes top of nose
••
calvaria from inferior direction, looking up into eyes and nose
• Ring Fracture of Cranial Base
o Results form either tension or compression at the craniumvertebra interface
o Body pushed into or pulled away from brain caseo Can ID tension or compression by beveling of the fracture lineo Ring shaped fragment of bone that will break off into skullo Ex. Falling and landing on top of head
o• CoupCountrecoup
o Injuries result from same blow, but cause two different wounds opposite of one another
o Force of impact has counterforceo In case of someone hitting their head in fall, one injury is from the impact
and other from corresponding negative pressure exerted opposite to that point
Summary
What affects damage caused by blunt force trauma?
GSW: Projective TraumaMost common in USFirearms involved in 2/3 of all homicides in USNeed to know relationship between firearms, types of bullets, and damageBallistics is study of all this
Bullet what actually flies through airCase holds powderFiring pin strikes primer, creates flash that ignites case with powder in it to provide force to fire bullet
Bullet basics such as gauge, caliber, jacketing, point types. • Caliber: measure of size and refers to diameter of a bullet and/or the barrel of a
handguno Generally measures in hundredths of an inch, although today man are
measured in mmo Common calibers: .22, .357, .45, 9mm etc: larger the bullet, larger the
caliber• Shotgun measured in terms of GAUGE
o Measures the maximum weight of a lead ball that would fit down the barrel of a shotgun
o Measured in tenths of a poundo 10 gauge shotgun would allow a ball weighing a 1/10 of a pound, 12
gauge is a 1/12 of a pound 10 gauge is larger than a 12 gauge opposite relationship as described for caliber
• Bullets themselves are described on theiro Profile
Shape of the bullet tip Most rifle bullets are SHARP point BLUNT bullets (used to describe round AND flattipped) are
usually found in handguns HOLLOW POINTS have an indentation in their tips. Can cause
enormous exit wounds, expand on impacto Internal composition
Solid lead: heavy and deforms easily Fragmenting: designed to explode on contact; encase pellets that
scatter throughout target on impact as casing ruptures; blunt tipped; produce more damage as soon as they impact body
o Jacketing: metal casing that is mean to reduce bullet deformation Full metal jacket: means whole bullet is encased in usually copper,
rifles Semijacketed: bullets are only covered partially Nonjacketed: “soft tipped” deform to a great extent while passing
though tissue• Bullet Aerodynamics: lots of variables, hard to say much with great confidence
o Amount of energy, bullet characteristicso Rifling, or cutting of spiral grooves into the internal barrel surface imparts
spino As a bullet continues its path (trajectory), it loses nice spin and begins to
tumble Damage to skin
• When gun shot, explosion of gases and powder out of end of barrel• Can make some assessment of distance to target (perp and decedent)• Suicide vs homicide• CONTACT VS DISTANCE
o Very important to distinguish between a wound caused by someone standing close or far, can corroborate or invalidate someone’s story
o Wounds on soft tissue show various patterns that can help you distinguish between the two
o Fired bullet discharge soot and gunpowder and produced soot and gases that can show up on body, determine range
If fired more than 2ft away (distant wound), not going to see much distinctive characteristics
Analyzing close contact bullet holes• Gases can cause tears in the skin near the bullet hole• Burning heat from barrel can burn the skin (if touching), cannot be washed away• Soot burned gunpowder, can be washed away, lighter than unburned
gunpowder doesn’t travel as far• Stippling powder tattooing, unburned gunpowder (travels farther) strikes the skin
causing abrasions, cannot be washed awaySoot and minor stippling: soot is black stuff, red arrows point to punctuae points where unburned powder hits with high velocity
Stippling or Powder Tattooing
Contact Gunshot: pushed directly against body or very close• When gun fires, resultant heat and pressure is great• Usually great deal of soot and gunpowder would cause stippling or superficial
burns on skin near entrance wound• In case of tight contact (direct contact of body and barrel) almost all gunpowder
is driven into body. Wound often star shaped or stellate due to expanding gas, no evidence of soot around edges
Hard contact wound: muzzle of gun jammed into skin, leaves seared blackened area that can’t be removed from skinSmall circle is bullet hole, large circle is searing; not soot because soot can be removed from skin
Stellate tearing due to buildup of gases and pressure under the skin, tearing of skin
Don’t see stellate development in some hard contact wounds, but do see muzzle burnsWhite arrow points to rim around primary entrance of bullet that reflects gases entered skin, but inflates it instead of tearingSkin puffed up and touched against sides of barrel
Can have stellate scaring in both entrance and exit wounds: difference is soot, presence of burned areasBlack arrows are burned areas from firing
Direct contact suggests suicide or execution, clear indications of burning on inside of skull, gas build up, muzzle burns
Loose contact gunshots: barrel held very close to body but not toughing it• There is some burnt tissue from hot gunpowder around wound and a little soot• Diameter of gunpowder burn quite small
o Some of powder escaped as weapon was discharged• A stellate wound is seldom observed, no pressure of gases being pushed directly
into bullet entry wound
• Muzzle held tightly against skin• Gas preceding bullet indents skin, allows some space for burned gunpowder to
escape• Leaves seared area (no removal)• As well as soot around the seared area, which
can be removed
Muzzle burns seen in loose contact gunshotNot the soot around the edgesImprints from shape of
muzzleProvides info on murder weapon
Close Range gunshot• can be distinguished from loose contact (has muzzle burn) because never bear
mark of gun barrel, are often accompanied by a ring of soon and burned skin
• less than 2 ft away, be wary of clothing• if gun is more than 7” away, stippling but little soot observed
o soot is lighter than unfired gunpowder, will fall away after traveling only a few inches from barrel end
Blue area larger because father away from body, allowing unburned and burned gunpowder to travel further and spread out more Area of soot deposited around seared area of skin usually much larger than in loose contact wounds
about an inch in diameterstippling apparent
stipplingdark bullet hole
close rangeless than 2ft
Odd bullet holes, such as keyhole wounds • Incomplete contact would, oblique relationship between body and gun, only
portion of muzzle in contact with bodyo Allows gas to escape and gun powder to escape but in only one direction
• Angled near contact woundo Not direct, not perpendicular o Hybrid type of bullet woundo Asymmetrical expression of burning or stipplingo Angled nearcontact wound show seared area on same side as muzzle of
weapono Bullet hole in red circles, box shows soot and burning, arrow shows
direction gun facing
Graze bullet Wounds: bullet impacts body at very shallow angle, bullet may not go into body
• Can allow you to tell which direction bullet came from• Skin TAGS point toward muzzle of gun
• Skin TEARS point in direction bullet had traveled
Black arrow shows direction bullet was going
Triangular pieces of skin (tags) point toward gun, bullet moving in same direction as tears
Shotgun Injury• shotguns are most destructive of all projectile weapons• propel numerous tiny pellets (bird or bucketshot) instead of single bullet,
extremely high velocity• can gauge decedent’s distance from shotgun via diameter of shotgun pellet spread
in their body (some general relationship)
Effects of Bullets on Bone• Will cause entrance and exit would if projectile has enough energy, not hindered
in passage through passage of bodyo Easy to tell which is which. Will tell you where perpetrator was
standing when gun fired
• Bullets create primary fracture at sight of impact, can cause significant secondary fractures in surrounding tissues if enough power
Direct/close contact wound showing bone burning and fracture
When bullet impacts bone, it knocks a piece out and creates hole: Plug and spall red arrow shows direction, plug and smaller pieces destroyedGives bullet wound its shape Two exit wound fragments
ID soft tissue wounds in terms of distance
Inward and outward beveling
• Link entrance and exit wounds to determine how many gunshots there were based on beveling
• Inward beveling refers to bevel on inside of bone at site of impacto Tiny hole on outside of skull, perhaps, with a beveling on the brain side
(larger on brain side): indicates entrance woundo Size of hole gets larger as you go from outside skullà in to brain side
• Outward beveling indicates exit wound, beveling on outside of skullo Size of hole gets larger as you go from inside brain sideà outside of skull
Entrance wound on Skull: turn bone over and look from inside see larger portion of bone is gone, plug and spall
(looking from inside of skull)
Exit wound: beveled margin in upper left, lower right of outside of skull
Wound Shape
• Shape of wound bullet produces depends on number of factors, may be hard to differentiate factors in some cases
o Its construction material, jacketing, etco Angle of trajectory in relation to boneo Angle of axis tumbling or straighto Type of wound that it forms (entrance, exit)
Entrance= cleaner, more likely to be round b/c less tumbling and loss of velocity
Exit= less clean, larger, postdeformation (after entrance of body) Could have just entrance and no exit
• Types of woundso Round angle of bullet acis and trajectory are perpendicular to bone
surface Entrance wound most common, exit wounds less so but not with
jacketingo Oval angle of bullet axis and trajectory no perpendicular to bone surgaceo Keyhole grazing shot, acute angleo Irregular more common with unusual bullet types, hollow and soft tip,
more common in exit woundsKeyhole: when bullet enters at very shallow angle, not perpendicular, creates entrance and exit wound in same areaOn right side, very clean looking round entrance wound, bone knocked off on left size making crescent
Tells you about where the person was standing who shot, portion that looks like exit (outward beveling) indicates direction bullet was moving(rightà left in picture)
Wound Size• Affected by wound type
o Exit larger than entrance in general• And bullet characteristics
o Caliber In general, smaller caliber= smaller wound Many exceptions and much overlap between caliber size wounds
have to be careful LARGER than expected bone thickness ^ deformation SMALLER than expected age of victim, deflection, sutural
o Construction affects rate of deformation, less deformation= smaller wound
o Velocity high velocity has greater energy and ability to massively destroy bone, very large wound
Wound analysis and how this relates to bullet characteristics, distance of shot, etc. • Description of wounds number, location, link entrance and exit wounds• Estimation of caliber rough guide to size• Bullet construction based on wound properties• Velocity low vs high as related to damage can help identify, get some sense of
murder weapon• Direction of fire easy with entrance/ exit
• Estimation of sequence for multipleso Can be trickyo ID all woundso ID as entrance/exit, link togethero Use radiating fractures to determine which shot came firsto Fractures stop at other fracture lines or sutures, provide information on
which came first
•o has outward beveling (exit wound)o red arrow= radiating fracture from bullet hole on other side of skull
(entrance)o white arrow= radiation fracture from exit woundo since the fracture on the white arrow stops at the fracture on the red arrow,
indicates that occurred second (which makes sense since it’s from the exit wound)
o Shot with so much power that the radiating fracture from entrance wound made it all the way around the head before the bullet exited, forming second radiating fracture (exit) that stops at first one
Examples
•o no signs of healingo very clean, round no tumbling on entranceo might be able to say something about caliber
•
o skull was burned, probably with some excellerant o burned outside of skull very badly but went out before it could reach
insideo identified series of matched bullet holes, second series of matched bullet
holes
•o linking of entrance and exit wounds for multiple GSWs, 3 bullet holes
•o Right os coxa, see similar patterns as you would see in head woundso Outward beveling see direction since flat like cranial vault
•o round, clean entrance woundo entrance and exit wounds similar in sizeo exit wound also has radiating fractureo bullet did not deform significantly since similar size entrance/exito high velocity to cause radiating fractures upon entrance AND exito may be associated with solid point jacketed rifle
Fracture lines and what they say about velocity. • Secondary fractures caused by intracranial pressure increases introduced by bullet
and accompanying gases• Production of secondary fractures depends on range from the target and the
kinetic energy of the bullet at impact• TYPES OF FRACTURE LINES
o Radiating Originate from site of impact, move outward in any direction esp
in entrance wounds Usually end abruptly at suture lines as the force dissipates, energy
runs along sutures
(exit wound, see outward beveling shot with powerful weapon)
o Concentric fractures Most common with very high speed projectile Result of massive force rippling outward from the site of impact
and intracranial pressure, concentric circle from impact site, can break bone as seen in pic
Occur around wound due to heaving of bone outward from initial impact
red arrow is concentric fracture, bullet hole on white arrow; high power firearm created concentric fracture ring
o
• Ricocheto Can occur usually with smaller caliber bullets or lead bulletso Internal ricochets occur in 1025% of cranial GSWs
oo can cause massive amounts of damage in brain, tricky to link entrance to
exit woundso can have lots of damage on inside of skull unseen from outside of skull.
May leave no exit wound
o
Sharp Force Trauma: • Narrow, focused application of compressive forces to the body• Injury by means of knife, ax, icepick, or similar instrument• Second only to gunfire as cause of homicidal death in US
Incision, puncture cleft, incision vs laceration, how to tell the difference • A CUT or INCISION is longer than it is deep• A STAB or PUNCTURE is deeper than it is long• A CLEFT or NOTCH is formed when the instrument is extremely heavy and
force is applied vertically, such as in case of axeo Sharp force trauma , combines some element of blunt force trauma (iaxe
has cleft but is also very heavy and causes other damage)• LACERATION: ex someone is punched and a cut opens up
o A sharp instrument CUTS and divides as it penetrates, usually no abrasions
o A blunt instrument abrades, crushed, and tears, often sparing small nerves, blood vessels and connective tissue which may be viewed as thin, delicate bridges within the wound
o Cut vs Laceration (swollen, pieces of skin)
• Sharp Force
Considerationso Hilt mark: may be an abrasion accompanying a sharp force injury hilt of
knife hits bodyo Presence of Fingernail scratcheso Contusion may form as a result of perp’s hand striking the victim as the
instrument penetrates deeply
ID blunt, sharp, projectile trauma and taphonomic changes
ID single vs double bladed weapons, ID puncture vs GSW • Assessing distinctive sharp force characters
o Single or double edged (dagger)?o Serrated?o Knife or scissors?o How many blows per injury?
• SingleBladed Stab Woundso Often cause on edge of the wound to appear angular when pinched
together Asymmetrical Top portion is rounded, bottom portion is pointed or angled
o When not pinched, elasticity of skin obscures this trait
o• DoubleBladed Stab Wounds
o Will have two angular surfaces at either endo Wound was stitched closed before the individual died:
• Scissor Stab Woundso Made with open scissors: see multiple stab wounds that may be confused
with multiple stabs from knife Two wounds are constantly along SAME PLANE if not equidistant All but ensures perp will injure himself, as well
o Stabs with closed scissors produce square punctures in both skin/soft tissue and bone
o• How many blows per injury?
o Like blunt force, single sharp force blow can produce multiple injurieso Always check angle of impact to see if a single blow could have been
responsibleo Straight skips in pattern of a cut along a single line may be caused by bony
ridges, loose skin or a dull blade (blade dragged against skin not multiple attacks)
• take knife and line it up with both wounds on eyeso Sharp force trauma and bone
Results in discontinuities in bone• Fracture lines secondary, result from force of blow• Hinge fractures chips of bone that adhere to primary
trauma site, indicative of perimortem injury• Wastage chips of bone that break away from primary
trauma site
Discuss wound characteristics of: punctures, incisions and clefts • Eight characteristics of sharp trauma
o The instrument1. Cross sectional shape weapon shape
• Puncture/Stab wound ice pick• Incision/Cut knife• Cleft axe, heavy object
2. Width weapon shape, direction of blow3. Depth force and weapon shape4. Length shape and direction of blow5. Striations line sin cross section of wound that indicate direction of
force,• Metal itself not going to be entirely smooth, little bits and
fragments• Causes striations and lines, can reconstruct direction• Differentiate puncture would from incision
6. fracture lines level of force, weapon7. hinge fractures level of force, weapon8. Wastage level of force, weapon
• If large person used heavy axe, may expect to see lots of secondary fractures and wastage
1. Puncture wounds in bonea. Cone shape cross section (i.e. ice pick has conical tip)b. Can be all widths, depths, and lengths depending on force and objectc. Striations are vertical (as if stabbing in and pulling out, lack of totally smooth
object causes striations)d. Fracture lines may be presente. Hinge fracture may be presentf. Wastage is minimalg. Cranial vault with multiple wounds: B is best example of puncture, can see
cross section
young (cranial sutures), very clear weapon shape diamond suggest double edge knife
can see beveling2. Incisions on Bone
a. Defects longer than wideb. V shaped cross section (knife shape is V shaped)c. Can be narrow or wide, shallow or deep, and short or long depending on force
and object
d. Striations are horizontal, knife being dragged along bone, run in same direction of cut
e. Usually no fracture lines force is parallel to bonef. Usually no hinge fracturesg. Wastage is minimal
This person was beheaded or had their throat slit, multiple cut marks
3. Cleft Wounds on Bone: heavy object with sharp blade, like ax, applied in perpendicular fashion
a. V shaped cross sectionb. Wide wounds that are deepc. Can be short or long depending on objectd. Striations are verticale. Fracture lines may be present secondary like a blunt force traumaf. Hinge fracture may be presentg. Wastage can be significant h. Multiple attacjs
i.
j. axe or machete, bone “filleted” off at very shallow angle, shows striation very well (parallel lines, best seen in top)
k.
l. asymmetrical appearance of cleft wounds, probs from axe
What are striations, wastage.
Force and the blow
Signs of beheading • massive cleft type injury• spongey area of bone shouldn’t look like that, should have piece of bone sticking
up (what your head moves around)
Taphonomy:
Dismemberment, saws and how to tell saw type • Dismemberment
o Generally leaves identifiable toolmark on bone
o Evidence of dismemberment is pretty clear indication of homicide, foul
playo Why dismember?
Cover crime scene Make identification of victim more difficult, can hide medical
things Disgrace the victim (psychological profile)
o Manner of dismemberment can provide information on assailant’s state of mind
If too precise: indicates skill with butchery• Localized cutmakrs joints
If too brutal: indicated disregard for victim rather than convenience (move body, hide body easier)
• Suggests person who killed victim and victim knew each other
• Generalized cutmarks everywhereo (If dismembering body, make sure it isn’t found. Doing so generally
provides more information on assailant, adds lots of blood to crime scene, may result in assailant’s injury, adds another implement to hide which can be linked back to crime scene not easy to do in general!)
o Analysis is based on properties of saws: cross cut, rip saws, hand held saws, power saws, chain saws
Important characteristics:• Number, size of teeth• Power source• These determine cut characteristics
Three Types of dismemberment cuts• 1) Superficial False Start Scratches made during pull
stroke, skipping along bone, before primary kerf is madeo typical of hand sawso ferk is groove in bone caused by saw action
probs chain saw
• 2) False Start Kerfs bouncing of saw on bone before primary kerf established
o Generally made during push strokeo Common with handsaws
o
• 3) Sections Bone Cuts very deep kerfs that don’t completely go through bone (no 2 new pieces made)
o Most useful type of dismemberment cut for forensics:
Tells a lot about the saw used Examine walls, floor of kerf Can provide information on position of body
o Analysis of Saw Marks: 5 Features1. Direction of Cut assess body position, handedness
a. Direction of progress e.g. from anterior of bone to posterior
b. Inferred based on location of false start kerfs and breakaway spur (tendency for last little bit to break off) (picture, red)
i. No false start scratched of kerfs on there (white, where bone cut started)
ii.2. Number of Teeth0 accuracy depends on type of cut present, crude
estimate a. Rough kerf walls= fewer teeth/square inchb. Smooth kerf walls= more teeth/sq inc.
3. Blade Width only for intact kerfsa. Blade width not equal to kerf width bc teeth are angled on
all saw blades, not up and down
b. Kerf width generally wider than actual saw bladec.
4. Shape of Blade striae in cross section of kerf follow shape of blade
a. Fixed radius= circular saws (chain saws= oval, hand saw depends on person’s cutting)
i. Same shape throughout kerf wall, homogenous in orientation and size
b. None fixed radius chain saws and hand sawsi. Changes in size and orientation of striae indicate a
change in direction of attack during cutc.
i. break away spur not clean; change in striae direction; uneven walls; spur and kerf show direction of cut
ii. consistent with hand saw5. Energy source hand or power saw
a. Hand saws produce rougher sides to kerf wall, changes in striae direction
b. Power saws produce smoother sides to kerf wall
c.
d. cut completely in two, number of kerf walls (red), wastage and cut marks, hand saw
i.
o Dismemberment: Cannibalism Rarely about hunger Ancestor worship, enemy violation, power and spirit consumption For law enforcement, often seen in context of sociopathic serial
killer Cannibalism Signs
• Often difficult to say for sure if bones were consumed• Look for signs of butcher, not just dismemberment,
controversial o Similar as to what is seen on (hunted, consumed)
animalso Cutmarks not near joints, on long bone shafts can
indicate removal of meanto Pot polish is found on bone surfaces that were
cooked Bones hit sides of pots from cooking, getting
polished and soft (like shells and rocks)o Red: joints, dismemberment purple: pieces of flesh
removed
o
• Animal scavenging dead bodies attract other animals (and insects)!o Alter bone surfaces, scatter crime scenes, completely destroy some boneso Carnivores do most damage can be confused with sharp force trauma
and other trauma to body Punctures tooth penetrates bone Pitting tooth fails to penetrate bone Scoring (shallow) and furrows (deep) groove
o West Memphis Three knife or animal damage?o Rodent damage on dry bone specimens
Have incisors that continue to erupt if they don’t wear them down need to chew, bones get chewed upon
o Process of Animal Scavenging1) Soft tissue of head and neck eaten2) Thorax opened and guts eaten3) Upper limbs separated from thorax4) Lower limbs separated from thorax
• Pitting, punctures, and furrows occur often near articular ends which are eaten first
• Envision a dog chewing on a bone•
ulna, ends chewed on• Fire Damage
o Used to cover crime sceneo Bone goes through color changed with temperature of fire
Yellowbrownàdarker yellowàblackàdark graylight bueàwhite Black= oils burned away and organics are carbonized White= calcium salts all that is left, very brittle Gives idea of how fire was made, accelerants, etc
o Shrinkage Fire is less than 700C: minimal shrinkage
700800C: 12% shrinkage 800C+: 1015% shrinkage has obvious effects on measurements of stature and sexual
dimorphism • Weathering
o Left on surface, buried will be weatherso Exposure to the elements, primarily sunlight
Sunlight causes both shrinkage and cortical sloughing. Latter eventually leads to complete deterioration of bone
Warping can also occuro Stages of weathering
o• Burial Damage
o Staining of bone due to soilo Cracking of exterior cortical surfaces similar to weathering and burningo Root can infiltrate bone, root etchingo Erosion of cortical bone surfaces due to acidity of soilo Burial recovery damage shovel and trowel markso Skull from marshy burial
o Root damage, infiltrating bone
o Gash caused from out of ground vs in ground? Gash lighter in color if placed there after removal
Signs of animal scavenging, water transport • Water transport and disarticulation
o Results depend on degree of articulation of bodyo Whole bodies float, then sink, then float again as gases develop as part of
process of putrifaction Will explode and sink again…
o Disarticulation follows somewhat standard pattern Head and hands Feet, lower limbs, remainder of arms
o Isolation Elements are Affected by Water According to weight, shape, and density of elements Some elements float away and have fluvial properties (transport
group) lighter, less dense, rounder elements Lag groups tend not to move as far heavier, denser, flatter Can be useful for crime scene recovery and definition of extent of
crime scene
General taphonomy, what is it? Science or study of burial environments, or what happens to a body after death and before recoveryGoal: reconstruct forces that impacted/affected body from time of death until time of recovery
“necrokinetics”
Dismemberments, animal scavenging, fire damage, weathering, burial damage, water transport and damage
Burning changes, weathering
Please be prepared to view images and make an assessment of trauma.