Name:______

Blood Spatter Analysis Labs

Part A: Vertical Drip Pattern Recognition

Materials:
Simulated Blood Meterstick5x8 NotecardsRuler with mm10 mL graduated cylinder

Part 1: Single Blood Drop Patterns

  1. Hold the bottle of simulated blood upside down in a vertical position so that the dropper end is 15 cm (use the meter stick) from the note card.
  2. Gently squeeze the bottle so that only ONE drop is released from the bottle at the 15 cm height and lands on the card
  3. Mark this specimen as vertical drop at 15 cm.
  4. Reposition the blood bottle so that the tip is 30 cm from the target surface. Repeat steps 2 and 3, labeling for the correct height.
  5. Follow this same procedure for all heights listed on Data Table A. While allowing blood drops to dry, sketch all drops in Data Table A.
  6. When the blood dries, measure the diameter of the CIRCULAR parts of the drop in millimeters. If there are spines or protrusions on the drop, disregard them as part of the measurement. Record these measurements in Data Table A.

Part 2: Multiple Blood Drips Pattern Recognition

  1. Using the simulated blood, drip ONE drop of blood onto a target surface from a height of 30 cm. Do not move your hand from the 30 cm position. Drop a second drop of blood onto the first. Note any change in the blood drop pattern after dropping the second drop into the first. Record your observation in Data Table B.
  2. Drop a 3rd blood drop from the 30 cm position so that it lands on the stain from the first two drops. Record your observations.
  3. Drop a 4th blood drop from the 30 cm position so that it lands on the stain from the first three drops. Record your observations.
  4. Obtains a clean target surface. Place approximately 2-3 mL of simulated blood into the graduated cylinder. Position the cylinder 30 cm above the target surface, and pour the entire volume of blood all at once at the target. Observe the pattern and record your observations.

Data Table AData Table B

Height of Blood Drop / Sketch of Blood Drop / Diameter of Blood Drop (mm) / Blood Drips / Description and Sketch of Blood
15 cm / One
30 cm / Two
45 cm / Three
60 cm / Four
75 cm / Large Volume
100 cm
150 cm

Part B: Relationship Between Shape and Impact Angle for Bloodstains

Materials:
Simulated Blood5x8 CardMeter StickClip BoardProtractorTape

Instructions

  1. Assemble an Impact Angel Apparatus:
  2. Table the crease of the clip board to the edge table. The tape should act as a hinge for the board.
  3. Hold the protractor to the edge of the clip board so that the protractor is perpendicular to the table top and aligned so that the center of the protractor is at the hinge of the clip board on the edge of the table. See Figure 1 on the board.
  4. Select an impact angle to study. Data Table C includes angles of 10° to 90°. Once you have selected an impact angle, indicate the angle on the card and then attach the card to the board. Set the angle of the board using the protractor so that the board will have the correct impact angle. To obtain the desired impact angle, set the board to the protractor at the desired angle.
  5. Using the simulated blood, place the dropper at approximately 30 cm above the board.
  6. Let ONE drop come out at the dropper. You may do additional tests on the same card if necessary, just move your hand to the side. Don’t let drops over lap. Leave the card is position from 2-3 minutes before removing it.
  7. Allow the drops to dry. Record Observations on Data Table C.
  8. Repeat steps 2-5 for all the remaining impact angles.

Data Table C

Impact Angle / 10° / 20° / 30° / 40° / 50°
Sketch
Description
Impact Angle / 60° / 70° / 80° / 90°
Sketch
Description

Part C: Blood Stain Patterns and Impact Force

Your teacher will demonstrate a variety of blood stain patterns for you. Please draw the pictures below in the appropriate boxes.

Walking Drip Pattern / Wipe / Swipe
Other Transfer Stains / Arterial Spurts-Vertical / Arterial Spurts-Horizontal
Cast off Spatter / Medium Velocity- 90° / Medium Velocity- non-90°
High Velocity- 90° / High Velocity- non-90°

Questions

  1. How are blood drops at different heights alike? How are they different?
  1. How do the large volume and dripped volume blood patterns compare
  1. Using a computer or on graph paper, create a graph that illustrates the Drop Height vs Diameter for the blood drops in Part A. Attach the graph and describe the pattern below.
  1. Given the following diameters of blood drops, from what height (approximately) did they fall?
  2. 8mm= ______
  1. 14 mm=______
  1. 18 mm=______
  1. Research a case where blood spatter analysis played a key role in solving the case. Write a brief description of how the evidence was analyzed and used in the case.
  1. Do you agree or disagree with the following statement, “Blood evidence can be used long after the crime.” Explain.
  1. Draw and describe the approximate size and shape of a droplet of blood that:
  2. Has fallen straight down from a height of four feet
  1. Has fallen from a running person from a height of four feet
  1. Describe how you tell the different between medium velocity and high velocity blood spatter.