Blood Type Identification Chart
Researching Blood-Spatter Patterns
Objectives
At the end of this activity, you will be able to:
Outline to Complete the Activity
Background Information
Crime-scene investigators use blood-spatter patterns to help them understand what happened at a crime scene. Is a person’ s description of the crime consistent with the blood-spatter analysis?
Procedure
At the end of this activity, you will be able to:
- Recognize and describe different blood-spatter patterns.
- Design a technique to simulate and model various blood-spatter patterns.
- Prepare expert witness testimony analyzing a blood-spatter pattern. Include in the testimony a possible scenario of how that blood-spatter pattern resulted, as well as evidence to support the scenario.
- Working with one other team, conduct a peer review of each other’s models and presentations.
- Summarize any revisions or improvements that resulted from the peer reviews.
Outline to Complete the Activity
- Brainstorm ideas and gather materials.
- Produce the model and create the simulated blood-spatter pattern.
- Present models and expert witness testimony.
- Prepare a list of suggested improvements from the peer review.
Background Information
Crime-scene investigators use blood-spatter patterns to help them understand what happened at a crime scene. Is a person’ s description of the crime consistent with the blood-spatter analysis?
Procedure
- Each group selects one type of blood-spatter pattern from Blood-Spatter Patterns.
- Each team should research bloodstains patterns.
- View slow-motion videos of blood-spatter. Google “Bloodstain Pattern Video Collection (Ames Lab)” or www.ameslab.gov/mfrc/bpa_videos.
- Brainstorm ideas of how to create your blood-spatter model.
- You will be given artificial blood to create your models.
- What type of surface will be your target surface?
- What instruments will you need to produce the blood spatter?
- What calculations might be needed for your blood spatter pattern?
- What procedure will you use to produce the blood-spatter stain?
- Your model should represent the blood-spatter pattern selected by your team.
- Upon completion, each team will present its model to another team. The presentation should model the expert witness testimony that might be given at a trial. Include the following in your presentation:
- Your description and analysis of the blood-spatter pattern. Including identification of the different parts of the blood spatter pattern.
- Relate this particular blood-spatter pattern to events at the crime scene that could have produced this type of pattern.
- Support your claims using evidence from scientific sources.
- Listen to another team’s presentation, and view its model of a blood-spatter pattern. Prepare a list of suggestions or modifications of the team’s testimony that would enhance its model and presentation.
- Modify your presentation and design incorporating the changes suggested during peer review.
- Write a crime-scene scenario that could be applied to your team’s blood-spatter pattern.
- Present your revised model and presentation to another team and then to the class.
Labs
Prepare for the Test
Things you should know:
- Explain what type of evidence are blood and bloodstain patterns.
- Explain and identify the different types of blood stain patterns and how they are formed.
- How to identify blood types.
- How to calculate the angle of impact of a blood spatter.
- How to determine the area of convergence.
- How to determine the height of origin.
- The relationship between height and blood spatter patterns.
- How velocity impacts blood spatter patterns and how to identify the high, med and low velocity impact patterns.