Download Free Medical Forensic Investigations-Bloodstain pattern analysis PowerPoint Presentation

Forensic Investigations-Bloodstain pattern analysis PowerPoint Presentation

DOWNLOAD MEDICAL POWERPOINT PRESENTATION

About This Presentation

Description : Check out this medical presentation on Pathology, which is titled "Forensic Investigations - Bloodstain pattern analysis", to know about bloodstain pattern analysis in Forensic Investigations.

Tags : Pathology, Forensic Investigations, Bloodstain pattern analysis

Published on : Aug 03, 2021 | Views : 2298 | Downloads : 9

Shareable Url :

Embed Code :

Comment

Transcript

Slide 1-

Forensic Investigations Bloodstain pattern analysis
Slide 2-

What is bloodstain pattern analysis? The bloodstain patterns left by falling, projected or smeared blood can be analysed by trained crime scene investigators. Careful observation and measurement of the position and shape of bloodstains can give lots of information about the direction of travel, angle of impact and the speed or velocity of the blood droplets.
Slide 3-

Definition “Through the examination of bloodstains and bloodstain patterns, in association with knowledge of the underpinning sciences, they provide a determination of the physical events responsible for their deposition.” RCMP - Royal Canadian Mounted Police
Slide 4-

Why is it importantin forensics? Bloodstain patterns can be used to prove or refute a suspect’s account of what happened. The information from the bloodstain patterns can possibly be used to reconstruct a crime. Bloodstain pattern analysis can tell us the “how” of a crime.
Slide 5-

Blood Blood is a fluid that makes up approximately 8% of the weight of a human body. Females have approximately 4-5 litres while males have between 5-6 litres. Blood is made up of cells (red blood cells and white blood cells) plus platelets in a yellowish liquid called plasma. Plasma contains gases (oxygen, carbon dioxide) and molecules such as proteins, fats and carbohydrates (sugars).
Slide 6-

Properties of blood Blood has certain properties that can be compared to water.
Slide 7-

Surface tension Surface tension is an upwards force that enables insects such as a water strider to “walk on water”. Image: Water strider: David Cappaert, www.insectimages.org
Slide 8-

Surface tension Surface tension enables blood droplets to maintain a sphere shape. Image courtesy UWA PhD research student Mark Reynolds.
Slide 9-

Traveling blood droplets When a force is applied to a mass of blood, the blood breaks into droplets. The droplets fly through the air as “perfect” spheres due to surface tension. Image used with permission from Tom Bevel & Ross Gardner, June 2006.
Slide 10-

Stages of impact
Slide 11-

Stage 1: contact & collapse Image used with permission from Tom Bevel & Ross Gardner, June 2006.
Slide 12-

Stage 2: displacement Image used with permission from Tom Bevel & Ross Gardner, June 2006.
Slide 13-

Stage 3: dispersion Image used with permission from Tom Bevel & Ross Gardner, June 2006.
Slide 14-

Stage 4: retraction Image used with permission from Tom Bevel & Ross Gardner, June 2006.
Slide 15-

Height and size of blood drops A blood droplet released from a 1m height will be smaller than a blood droplet released from a 1.5m height. This is because the velocity of the blood droplet released from a higher height is greater.
Slide 16-

Surface and shape of blood drops Images courtesy DUIT Multimedia: Paul Ricketts.
Slide 17-

Low impact Low impact is really blood under the influence of gravity - it just falls. Image courtesy UWA PhD research student Mark Reynolds.
Slide 18-

Medium impact Medium impact occurs when a force such as a bat is applied. Image courtesy UWA PhD research student Mark Reynolds.
Slide 19-

High impact - fine mist of droplets Image courtesy Stuart James, February 2007
Slide 20-

Angle of impact Image used with permission from Stuart James, February 2007.
Slide 21-

Origin of blood Image used with permission from Tom Bevel & Ross Gardner, June 2006.
Slide 22-

Reconstructing the crime With the evidence that is collected, the crime scene investigator attempts to reconstruct the crime. This involves trying to work out what events happened and the order that they happened. Image courtesy UWA PhD research student Mark Reynolds.
Slide 23-

What other things you may need to know to reconstruct a crime Forensic pathology results - post mortem information Forensic biology results - eg, DNA Witness statements Impressions - fingerprints, shoeprints Ballistics Entomology evidence if appropriate
Slide 24-

References Bevel, T. & Gardner, R.M. 1997 Bloodstain Pattern Analysis. With an introduction to crime scene reconstruction. Boca Raton CRC Press LLC. James S.H., Kish, P.E. & Sutton, T.P. 2005 Principles of bloodstain pattern analysis : theory and practice. Boca Raton, CRC Press LLC. Mark Reynolds, PhD Research Student, Centre for Forensic Science The University of Western Australia. Paul Ricketts, Photographer, DUIT Multimedia, The University of Western Australia.