Footwear and Bloodstain Evidence Flashcards
What is footwear referred to as?
“forgotten evidence” often overlooked.
what might footwear evidence provide?
- type and make of shoe
- approximate size,
- number of suspects,
- pathway in,
- possible sequence of events in crime scene
Why is footwear evidence overlooked?
- lack of training in proper search techniques, photography, and preservation of evidence
- value of this evidence is not understood
- lack of education in the comparison of footwear and report writing
What impressions were found at the Lloyd homicide investigation?
- footwear impressions from both Williams and Lloyd
- tire track impressions
how did the impressions found at the scene aid in Williams arrest (Lloyd homicide)?
- Williams went through a police checkpoint driving that make of vehicle
- he was wearing the same boots he wore at the scene
What was the key piece of evidence in the OJ Simpson case?
his Bruno Magli shoes that were found at the case
why did OJ’s shoes give him away?
he lied about having the Bruno Magli shoes but was clearly documented to own a pair in multiple images
Where must a scale be placed in a shoe impression?
on plane with bottom of the impression
How do you take impression photos?
oblique lighting must be used to make shadows showing depth
What are class characteristics?give an example.
manufactured characteristics where they are intentional or unavoidable characteristics repeating through process
- ie. logos and patterns
What are accidental characteristics? give an example.
random characteristics that are dependent on chance.
- ie. evidence shoes being worn like nicks or damage
explain the process of a gelatin lifter. what is it for?
- sheet of rubber with low adhesive gelatin layer that can lift prints from almost any surface
- used with fingerprint powders on 2D surfaces
- for footwear impressions or fingerprints
explain the process of a electrostatic lifter. what is it for?
- charging a plastic film placed over dust print creating electrostatic adhesions and draws the film onto the surface
- for footwear impressions or fingerprints
explain the process of casting. what is it for?
- dental stone or other setting liquid placed on a print
- used for recording 3D footwear impressions found in snow, sand, or soil.
where are 3D impressions typically found?
outside bc dirt
Where should the camera be relative to the impression?
on plane with the impression and the scale should be level with the bottom of the impression
what depth of field should be used for 3D impressions?
high depth of field (F18-F22)
What should also be included in impression photography?
an identifier usually number data (case number, date etc.) and initials.
what can be used to enhance impressions usually in snow?
coating the print with snow wax to give contrast
What do you include in notes on footwear?
- where found
- direction of travel
- detail in impression
- substrate
- how preserved (photos, casting)
- development enhancement technique
- how many
- how many different types
- any footwear for elimination from witnesses, victims, or suspects
If a shoe is taken from a suspect 6 months after a crime what might happen?
accidental patterns many emerge due to wearing
how might you compare an impression to the hypothesized match?
superimposing it over the real print with clear acetate copy
What is Leucocrystal Violet? when is it used in relation to other enhancement techniques?
visualized blood turning deep purple in contact with blood
- used after luminol
What is the purpose of Blood pattern analysis?
drawing conclusions about the nature, timing and other details of the crime
What can you gain from BPA?
- direction which blood originated
- angle at which blood struck a surface
- location or position of victim at time of wound
- movement
- number of blows
approximate location/position of an individual delivering blows
How can you tell directionality of blood?
the tail indicates direction blood is flowing to.
what is the equation for determining angle of impact?
Sin A = width of blood stain/length of blood stain
what is forward spatter?
when blood travels away from the source in the same direction as the force that caused the spatter
What is back spatter?
when blood travels backward from a source that caused the spatter
What would the diameter of blood droplets be if they were travelling at 5ft per second?
greater than 4mm
If droplets of 1-4 mm in size are created approximately how much force in ft/s
about 5-25
what type of crime is medium velocity of spatter associated with?
blunt force trauma
What kind of spatter produces droplets of 1mm?
high velocity spatter
What kind of effect is created by high velocity spatter?
misting effect
define the area of convergence
where lines traced through the long axis of a 2D plane of several individual bloodstains.
define the area of origin?
location in a 3D plane where blood originated
what do you use to find area of origin?
area of convergence and angle of impact
What is gunshot spatter?
possible blowback on weapons muzzle caused by firing at close proximity
what is cast off spatter?
blood is flung from an object that has blood on it
what is arterial spray spatter?
bloodstain caused by spurts of blood resulting from blood exiting under pressure from arterial injury
When blood spatter is lighter what kind of pattern is it?
usually expirated blood diluted due to saliva
define a void pattern
area free from spatter where an object or person blocked the deposition of blood onto a surface or object
what is a transfer pattern
when an object with blood on it touches another object that did not have blood on it
skeletonization happens when?
when the edges of a stain is dry to the surface usually with a wiped away middle (cause its wet)
harder and less porous surfaces cause what kind of spatter?
less spatter with round edges
rough surfaces cause what kind of spatter?
irregularly shaped stains with serrated edges or satellite spatter
what are the methods of documenting bloodstain pattern evidence?
- notes, photos, and sketches
- grid method: grid over entire patter
- perimeter ruler method: rectangular border of rulers around pattern
what is luminol?
reacts with iron in hemoglobin and releases blue light
T/F: luminol is specific to blood.
false
what should you have in tire impression photos?
as much as possible of one complete tire rotation.
what should be measured of a tire track impression
- tire track width
- turning diameter
- wheel base
T/F: tire track notes are the exact same for footwear?
true just with exemplar tires
what is SICAR?
shoeprint image capture retrieval.
who maintains SICAR?
RCMP
who created the tire track database?
Cpl. Jim Giczi RCMP
who maintains the tire track database?
the RCMP
