1. Forensic Implications of Circulatory System

2. Blood at scene – used to ID victim or perpetrator
Blood type can exclude
Nuclear DNA – individual evidence – can ID
(RBCs – no nucleus or DNA; WBCs – have it)

3. Presumptive Tests Hemastix – if red stain is blood
- plastic strip treated w/ reagent, moistened w/ dH2O
- if turns green – blood
Luminol – mixed w/ H2O2 – is oxidized
- to test large area for blood
- emits light

4. Presumptive Tests Leucomalachite green – similar rxn
- in presence of iron, turns blue-green
Kastle-Meyer test –
- phenolphthalen turns pink

5. Scene Photograph & document scene
Collect samples of blood separately from others
If on object, collect whole object
If on large object, collect only blood

6. Scene To collect dried blood – - use wet swab
- use fingerprint tape to lift stain
- scrape blood into paper bag
If wet blood, need to dry first

7. Collect evidence from suspect
Samples = control or known sample for comparison
Used to make a DNA profile to ID

8. Lividity = pooling of blood in the direction of gravity
Livor mortis = postmortem change in color caused by lividity
Appears 30 min – 2 hours after death
Not fixed yet – pooled blood can shift if pressed
Fixed after 12 hours – irreversible and permanent

9. Lividity
B/c fixed – can be used to determine if body was moved after death
Patches of lividity in different areas of body indicate body was moved
After fixed, check position of body with lividity pattern

10. Lividity Bluish-purple to reddish-purple near ground
Becomes darker over time
b/c oxygen separates from hemoglobin -> purple pigment (deoxyhemoglobin)
Areas away from ground - pink

11. Clues from Lividity Bright red - CO poisoning
Bright pink – hypothermia, body refrigerated shortly after death, cyanide poisoning
Dark brown – lethal doses of nitrates, aniline, & potassium chlorate (forms meth-hemoglobin)

12. If arm or leg hanging when person dies, petechiae (= small red dots underneath surface of skin) may show

13. Blood Spatter Position of victim & perpetrator Use laws of physics
Blood – high viscosity (= liquid’s resistance to flow)
Blood – high surface tension – allows blood to retain its shape when contacts other object

14. Blood Spatter
Velocity blood travels as it leaves body combines with gravity producing a certain path
Low-velocity spatter
- if person moves after losing blood from stab wound, blood falls down  large droplets

15. Blood Spatter Medium-velocity spatter - from blunt force trauma
- blood spurts out from body

16. Blood Spatter High - velocity spatter - from gunshot wounds
- tiny droplets, like a fine spray

17. Blood Spatter
Arterial spray
- based on heartbeat pattern

18. Blood Spatter Useful in determining: - position of victim
- type of weapon or tool used
- # of times victim was hit, shot, or stabbed
- if victim moved after assault

19. Blood Spatter After evaluation, may determine: Events of crime
Sequence of events
Who was or was not present

20. Lin