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Ch 8 Spatter, Study notes of History

History

surrounding a shooting, stabbing, or beating. Blood Spatter Analysis. Analysis of a spatter pattern can aid in determining the: • direction ...

Typology: Study notes

2022/2023

Uploaded on 02/28/2023

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ilyastrab 🇺🇸

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Ch8Spatter
1
BloodSpatterHistory
•
1894Pitoroskiwroteearliestreferenceto
bloodspatteranalysis
•
In1939,Balthazardwasfirsttoanalyzethe
meaningofthespatterpattern.
•
In1971,Dr.HerbertMacDonnellusedblood
spatterasatoolinmodernforensicexamination
BloodSpatterAnalysis
•
Whenawoundisinflicted,abloodspatter
patternmaybecreated.
•
Ittakesagroupingofbloodstainstomakea
bloodsplatterpattern.
•
Thepatterncanhelptoreconstructtheevents
surroundingashooting,stabbing,orbeating.
Blood Spatter Analysis
Analysisofaspatterpatterncanaidin
determiningthe:
•
directionbloodtraveled.
•
angleofimpact.
•
pointoforiginoftheblood.
•
velocityoftheblood.
•
mannerofdeath.
BloodSpatterAnalysis
•
Bloodisathickmixtureofcellsandplasma.
•
gravity,cohesion,adhesionandsurface
tensionactontheblooddroplets.
•
gravitypullsblooddownandthedroplet
elongates.
•
becausebloodiscohesiveitisattractedto
itselfandtendstosticktogetherinsteadof
separating.
BloodSpatterAnalysis
•
Ifbloodfallsonaflatsurface,itscohesiveness
causingthebloodtopulltogetherandresist
flatteningout,sothetophasaspherical
appearancesimilartowaterdroplets.
Blood Spatter
Analysis
•
Whenbloodfallsfromaheightoratahigh
velocity,itcanovercomeitsnaturalcohesiveness
andform satellitedroplets .
Texturedsurfacesproducesmoresatellites
•
Whenitfallsontoalessthansmoothsurface,it
canform spikingpatterns aroundthedrops.
•
Noticethatspikesarestillconnectedtothemain
dropwhilesatellitesarecompletelyseparated
pf3

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Blood Spatter History

  • 1894 Pitoroski wrote earliest reference to bloodspatter analysis
  • In^ 1939,^ Balthazard^ was^ first^ to^ analyze^ the meaning of the spatter pattern.
  • In 1971, Dr. Herbert MacDonnell used blood spatter as a tool in modern forensic examination

Blood Spatter Analysis

  • When a wound is inflicted, a blood spatter pattern may be created.
  • It^ takes^ a^ grouping^ of^ blood^ stains^ to^ make^ a blood splatter pattern.
  • The pattern can help to reconstruct the events surrounding a shooting, stabbing, or beating.

Blood Spatter Analysis

Analysis of a spatter pattern can aid in determining the:

  • direction^ blood^ traveled.
  • angle^ of^ impact.
  • point of origin of the blood.
  • velocity of the blood.
  • manner of death.

Blood Spatter Analysis

  • Blood^ is^ a^ thick^ mixture^ of^ cells^ and^ plasma.
  • gravity,^ cohesion,^ adhesion^ and^ surface tension act on the blood droplets.
  • gravity pulls blood down and the droplet elongates.
  • because^ blood^ is^ cohesive^ it^ is^ attracted^ to itself and tends to stick together instead of separating.

Blood Spatter Analysis

  • If blood falls on a flat surface, its cohesiveness causing the blood to pull together and resist flattening out, so the top has a spherical appearance similar to water droplets.

Blood Spatter

Analysis

  • When^ blood^ falls^ from^ a^ height^ or^ at^ a^ high velocity, it can overcome its natural cohesiveness and form satellite droplets. Textured surfaces produces more satellites
  • When it falls onto a lessthansmooth surface, it can form spiking patterns around the drops.
  • Notice that spikes are still connected to the main drop while satellites are completely separated

Blood Spatter Analysis— Six Patterns

1902, Dr. John Glaister described 6 patterns: a. passive drops falling straight down (90 o) produces circular drops b. arterial gushes walls or ceilings produced by pumping action of the heart c. splashes shaped like exclamation points; used to determine position of the victim d. smears left when victim or suspect touches surface e. trails left when person moves; drops, gushes or smears f. pools person remains in one place bleeding heavily

Blood Spatter Analysis— Impact

Patterns can help investigators determine the type of weapon used.

  • Gunshot^ or^ other^ high^ velocity^ impacts^ produce^ a finemist pattern
  • Beating with a weapon produces a lowervelocity pattern with castoffs
  • Voids^ (empty^ spaces)^ in^ the^ pattern^ help^ determine the presence of a person or object moved after the attack

Blood Spatter Analysis— origin

  • Using the pattern, examiner can determine the angle of impact or convergence, a two dimensional representation of the location of the victim at the time of the injury
  • Point of origin three dimensional view formed using lines of convergence and angles of impact of at least two different drops of blood to identify the source and location of blood spatter determined by the mathematical relationship between the length and width of the drops

Blood Splatter Analysis— Directionality

  • As^ moving^ blood^ strikes^ a^ surface,^ cohesion, adhesion and surface tension affect its shape adhesion is the force between two unlike things such as the blood and the wall. surface tension is an elastic characteristic along the outer edge of a liquid caused by cohesion the attraction of like molecules
  • blood tends to adhere to the surface so the point of impact of the drop is darker and wider than the rest of the drop

Blood Splatter Analysis— Directionality

  • Momentum keeps blood moving in the same direction it was traveling
  • As^ drops^ move,^ they^ elongate^ and^ may^ produce^ a^ thin taillike appearance which points in the direction of movement
  • Satellites^ may^ break^ off^ and^ will^ appear^ in^ front^ of^ the moving drop. direction of movement

Blood Splatter Analysis— Location

of the Origin of the Blood

Lines of convergence

  • Draw straight lines down the axis of the blood splatters.
  • The^ blood^ originated^ where^ the^ lines^ converge.