1. First of the Day….

6. Blood spatter from a sneeze from a bloody nose
Blood Spatter Lab
Blood spatter from a sneeze from a bloody nose

7. “Remember… it’s blood ‘Spatter’ not blood SpLatter.”

9. Blood Drop
blood spatter animations

10. Eccentricity: of an ellipse is the ratio of the distance between the foci to the length of the major axis; this is necessarily between 0 and 1. If the ellipse has the Cartesian equation

11. Basically “eccentricity” is how “oval” and ellipse is…
Basically “eccentricity” is how “oval” and ellipse is…. Which one is most “eccentric?”

13. Measuring the shape of the blood drops

14. Impact angle = sin-1(arcsin) width (d) length (D)

15. Impact angle = sin-1 (arcsin) width length
drop on left: W = 1.8 cm L = 2.8 cm
Impact angle = sin-1 (arcsin) width length
= sin-1 (arcsin) cm cm
= sin-1 (arcsin) (0.643) = 40 degrees
Do first ….

18. ….

19. drop on right: W = 1.2 cm L = 5.23 cm
Impact angle = sin-1 (arcsin) width length
= sin-1 (arcsin) cm cm
= sin-1 (arcsin) (0.229) = 13 degrees

21. Formula for Table 1 Angle of Impact Lab
Impact angle = sin-1(arcsin) width length
¼” = one foot on diagram on your answer sheet
Formula for Table 2 Height above point of target
XY = tan(i) x XJ,
angle i being the angle of impact from the previous data table

22. Blood Spatter Alteration of bloodstain over time
Blood dries and clots over time.
Difficult to estimate the time the blood exited the body.
Clotted smears can indicate time of movement

24. Blood Spatter Determining Direction of Blood
The angle can be determined mathematically.
Width/Length, then take the inverse sin (sin-1).
This number is the impact angle (90 = perpendicular to surface; <10 at a sharp angle)