blood pattern analysis(droplet dynamics)
TRANSCRIPT
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BLOODSTAIN PATTERN
ANALYSISNiranjana.S.Karandikar
Msc-1
Roll No.12
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CONTENTS
History
Significance Of Bloodstain Pattern Analysis
Factors affecting Bloodstain Pattern formation
Formation Of Bloodstain patterns Droplet Dynamics In Flight
Droplet Dynamics on Impact
Determination Of Point of Origin
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HISTORY
1894 - Pitorowski wrote earliest reference tobloodstain pattern analysis
1939 - Balthazard was first to use physicalinterpretations of stains
1955 - Dr. Paul Kirk used bloodstain patterninterpretation as a defense witness in the SamShepherd case
1971 - Professor Herbert MacDonnell promoted
bloodstain pattern interpretation as a tool formodern Criminalistics. He is also known asFather of modern Bloodstain Pattern Analysis
1983The International Association ofBloodstain Pattern Analysis was formed
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SIGNIFICANCE
Origin(s) of bloodstain Distance of bloodstain from target
Direction from which blood impacted
Speed with which blood left its source
Position of victim & assailant Movement of victim & assailant
Number of blows/shots
The angle at which a blood droplet struck a
surface
DNA
Crime Scene Reconstruction
Handedness of assailant
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http://upload.wikimedia.org/wikipedia/en/0/0d/BPA_ellipse_example.jpg -
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FACTORS AFFECTING FORMATION OF
PATTERNS
Gravity
Surface Tension
Nature Of Surface
Force Height
Angle Of Impact
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As Height increases, the diameter of the stain also
increases(Angle of impact kept constant at 90degree)
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Droplet shape at different Angles of Impact(Height kept constant)
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DROPLET DYNAMICSIN FLIGHT
Factors:
Size
Air Resistance
Viscosity
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OSCILLATORYMOTIONOFDROPINFLIGHT
oblate
prolate
Direction Of Motion
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DROPLET DYNAMICSON IMPACT
Contact/Collapse
Displacement
Dispersion
Retraction
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DETERMINATION OF POINTOF ORIGIN
Convergence of lines drawn through the longer
axis of the stain in opposite direction of travel
Angle Of Impact
Sin = widthLength
(=angle of impact)
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Area of Convergence
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CONTD.
3D methods
Manual
Strings,lasers
Softwares Trajectories, developed by Dr.Alfred Carter,1987
Backtrack, Dr.Alfred Carter
No More Strings developed by Miller Forensic
Software of San Jose,CA in the year 1990
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Determination of Point of Origin using softwares
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REFERENCES
Bevel, T., Gardner, M. R., Bloodstain Pattern Analysis with an
Introduction to Crime Scene Reconstruction, Third Edition. , CRC Press,New York.
Genge,N.E., The science of Crime Scene Investigation The Forensic
Casebook., Ballantine Books, New York.
James, S.H and Nordby, J.J.. (2003) Forensic Science : An introduction to
scientific and investigative techniques., CRC Press, USA.
Segel,J.A., Saukko,P.J., Encyclopedia Of Forensic Sciences., AcademiaImprint
MacDonell, Herbert L.,Bloodstain Pattern Interpretation,Laboratory of
Forensic Sciences,Corning NY,1982,pg.4.
McDonald,J.E.,The shape of Raindrops,Scientic
american,Vol.190,No.2,February 1954
Slemko J (2005). Bloodstain pattern Analysis Tutorial. -Internet
Available on : http://www.bloodspatter.com/bloodstain-tutorial-page-3
Image Courtesy:How Stuff Works-Internet
Available on : http://science.howstuffworks.com/bloodstain-pattern-
analysis1.htm
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THANKYOU
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