blood pattern analysis(droplet dynamics)

7/27/2019 blood pattern analysis(droplet dynamics)

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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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blood pattern analysis(droplet dynamics)

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