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.  Hemastix – if red stain is blood - plastic strip treated w/ reagent, moistened w/ dH 2 O - if turns green – blood  Luminol – mixed w/ H 2 O 2 – is oxidized - to test large area for blood - emits light

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

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

6.  To collect dried blood – - use wet swab - use fingertip 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.  = 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.  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.  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.  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.  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.  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.  Medium-velocity spatter - from blunt force trauma - blood spurts out from body

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

17.  Arterial spray - based on heartbeat pattern

18.  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. After evaluation, may determine:  Events of crime  Sequence of events  Who was or was not present