Applying Logic and the Scientific Method to Bloodstain Pattern Analysis

1. Applying Logic and the Scientific Method to Bloodstain Pattern Analysis

2. Looking past the pipettes and white poster board • Basic courses show patterns created in a controlled environment (i.e. impacts on white poster board) • “Real life” often involves complex and dynamic events • This requires the analyst to expand their thinking – they must be able to take all kinds of variables into consideration when determining what mechanisms could have created patterns observed in the scene • Variable examples: • Multiple injuries • Activities of victim and perpetrator • Surface effects

3. Methodology • In BPA we need to rely upon methodology that allows us to keep an open mind, considers all (viable) possibilities in a non-biased manner and allows us to reach accurate conclusions. • Most analysts know that in BPA we follow the scientific method, but what does that mean? • Many analysts reach accurate conclusions but cannot articulate the process behind how they got there.

4. Methodology • What does it mean to have a methodology?

5. Scientific Method Experiment for Reconstruction

6. Scientific Method • Establishing and utilizing a methodology to reach the most accurate, tested, and unbiased conclusion should be of utmost importance to the bloodstain analyst. This can be done by applying the scientific method to bloodstain pattern analysis.

7. Scientific Method • No one universal scientific method • Most of us use some form of scientific method without consciously being aware of it • Experts may very well reach accurate conclusions, but not be able to explain how they arrived at it.

8. Scientific Method Organize- gathering, collecting data that is specific and relevant (objective) Analyze- identify individual patterns and find correlations among data Generalize- hypothesis formation, extend the relationship of the data beyond the given information Experimentation- test outcomes, collect supporting and questioned samples/data Conclusions

9. Scientific Method • Statements made by suspects, victims, and witnesses should not automatically be treated as facts, but rather as theories that should be tested against the physical evidence.

10. Scientific Method Step 1: Organize - gathering, collecting data that is specific and relevant (objective). This information should be observable and measureable. • Medical Examiner • EMT – Firefighters • Notes, Sketches, Photographs • Observing and identifying areas of blood

11. Scientific Method Step 2: Analyze- identify individual patterns and find correlations among data • Note those stains that make a pattern • Do the patterns have a relationship to those around them • Identify potential patterns, note the size, shape, and appearance of the stains

12. Scientific Method Step 3: Generalize- hypothesis formation, extend the relationship of the data beyond the given information • What is a hypothesis? • Educated guess • Form ideas of potential mechanisms causing the patterns.

13. Scientific Method Step 4: Experimentation- test outcomes, collect supporting and questioned samples/data • Evaluation of data collected at the crime scene • Based on physical characteristics of patterns • Further forensic testing and autopsy outcomes • Experimentation • Based on past experience and experiments • Based on an attempt to recreate patterns • Research and other bloodstain specific references

14. Scientific Method Step 4: Experimentation • Experimentation and testing of the theory should also include acquiring appropriate reports, such as autopsy reports, medical reports, lab reports, and so forth. • Test this theory against the evidence to see if it validates or contradicts the theory • If it contradicts the theory you must reformulate or consider additional events

15. Scientific Method Step 5: Conclusion • Conclusions should only be written when all of the facts are gathered and is generally the last step in the analysis of bloodstain patterns. • If analysts correctly apply the scientific method, they will have an awareness of other possibilities and will be able to explain why their conclusion is the best explanation or why other opinions may be flawed.

16. Scientific Method • Do not go into a scene with a preconceived notion of what happened and allow bias to occur • Do not make the scene fit the theory, make the theory fit the scene. • Multiple scenarios or theories should be formed and tested to prevent bias from occurring.

17. Scientific Method • Reproducibility • Validation • Peer or Technical Review

18. Methodology • Pattern Classification • Organize • Analyze • Reconstruction • Generalize • Experiment • Conclusions

19. Methodology • Pattern Classification • Locate areas of blood • Evaluate the stains size, shape, distribution, and appearance • Determine what stains may make a “pattern” or be from an event • Classify the stains or patterns

20. Methodology • Reconstruction • Gather contextual information • Injuries/autopsy • DNA reports • Officer/ first responder reports • Eliminate pattern classifications based on contextual information • Test victim/suspect/witness statements against pattern classifications