Serology - Blood Spatter Analysis

Goal: Determine the sequence of events and the approximate position of the victim when blood exited the body

Objective:

·        Understand the laws of physics concerning liquids such as surface tension and cohesive force.
·        Apply mathematical concepts into directional analysis of blood spatter.
·        Design the blood flight paths with strings or CAD.
·        Experience various problem solving strategies.

Equipments

Intro to Blood Spatter Analysis Kit

Advanced Tech in Blood Spatter Analysis Kit

Measurement tools (rulers, measuring tape, protractor, etc)

CAD software or BackTrack™

Strings

Procedures

This is the general procedure for blood spatter analysis.  Please follow any specific procedures that might have come with your ordered kits.

Introduction to Blood Spatter Analysis - Student Study Guide
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Take a close look how Englewood Academies trimed down the full activity sets for 9th graders!!!

1.      Instructor must go over “Safety Biohazard” in case the instructor has not done it in the previous activity.

2.      The teacher reviews theories and background information: mathematical and physical concepts in blood spatter analysis.

3.      Instructor must enforce the students to wear safety equipments before they touch any instruments and evidence, especially blood spatter samples.

4.      First, students will distinguish if stains are blood.  Then, they may perform serology as optional experiment if time permits.  Confirm if the spatter is from the victim’s blood.

5.      Students will determine what the position and shape of the blood spatter indicates.

6.      Students will investigate the relationship between the height that blood was dropped from and the diameter of the blood drop on impact.

7.      Students will analyze the surface where bloodstain is present.  By then, students should have some knowledge about the relationship between blood spatter type and surface texture.

8.      Student will design a visual model with blood flight path data they have collected.  The visual model can be made either with CAD software or old conventional way by using strings.

Analysis and Conclusion

·        State several reasons why wet blood would be more valuable than dried blood in a crime scene.
·        You probably have figured this out before the activity; however, use your best research skills and list several types of test that is available to confirm blood against dye or ink.  List pros and cons for each test you are listing.
·        In the serology section of Background & Theory page, it was stated that “Gravitational force acting on blood must exceed its surface tension before a drop of blood can fall.” Why must this be true? What would be the consequence if this statement is wrong?

Activity Length

·        2-3 class period for theory and background
·        Internet research time – collect information
·        2-3 lab periods for experimentation and data collection
·        1 class period for analyzing and group discussion.
·        Research assignment time – presentation and conclusion