Chapter 5 and 7 Powerpoint Flashcards
Reconstruction Patterns
generally cannot be collected; documented only
Identification patterns
can generally be collected and preserved; documented and collected; involves comparison between Q vs K samples
Questioned Specimen
Q, unknown crime scene sample; unknown origin
Known specimen
k, control comparison sample; known origin
K vs. Q = not a match
Exclusion; K is excluded an the origin of Q
K vs. Q = not enough information to determine
inconclusive; no conclusion can be drawn either way
K vs. Q = match
inclusion, K is included as the origin of Q
Inclusions
known sample is included as your source; can be a person or an item associated with a person (finger, shoe, tire, weapon)
exclusions
a known and questioned specimen do not match and could have had a common origin; absolute; just as important as inclusions and identification; DO NOT CONFUSE WITH inconclusive
inconclusive
if there are a few details present that do match, but not enough for an id, the examiner cannot exclude that Q and K are from the same source
individualization pattern comparisons
- physical match
- comparison of impression marks (footwear/tire mark; fingerprints; firearms and tool marks)
- shape and form comparison (handwriting comparison / questioned document examination)
Make sure same specimens are being compared.
General orientation of impressions is being compared (left v right shoe)
Compare class characteristics (category)
Compare individual characteristics (what is different)
Class Characteristics
defines class or category that objects belong to; not sufficient to define individuality alone; two categories - general and limited; result of manufacturing (rips in jeans, pattern on the bottom of shoe. etc.)
General class characteristics
characteristics intentionally produced by the manufacturing process; standard for every make and model of the item
limited class characteristic
characteristics unintentionally produced by the manufacturing process; unique to a certain mold, imperfections in the mold used
individual characteristics
accidental/ unintentional; random marks from wear; sufficient number of these will allow an examiner to make an indentification
physical match
matches between or among pieces of randomly fractured, torn, or cut object that might show that the pieces were originally part of the same item (find the origin)
Direct match: primary/first order
Indirect match: secondary/second order
direct physical match can occur if:
- the fractured or torn pieces are from a solid object
- the solid object is expected to fracture randomly
- the pieces can be matched back together
(capable of being realigned, cannot be forced back together, all of the pieces are available for a direct match. If there are pieces missing, it is an indirect match)
Examples of motors vehicle physical matches
paint chips; headlights; grill; exterior mirrors; lights; trim pieces
Examples of burglary physical matches
paint chips; wood; tools; glass; doors/trims
Examples of bicycle physical matches
reflectors; lights; tires; spokes
Examples of miscellaneous physical matches
buttons; fingerprints; knives; bones; stones
Indirect physical match can occur if
some portions of the item are missing; the item is not solid (fabric); the item has distorted or poorly define edges
An indirect match is often the result of
a complex pattern that reaches across the boundaries of each piece.
Examples of indirect matches
matches; paper documents; money; checks; stamps; sheet plastic; etc.
Impression
encompasses imprints and indentations
Imprints
2D representation of an object in some kind of medium on a hard surface
Indentations
3D representation of an object left in a soft, impressionable surface.
Striation
a number of parallel or nearly parallel lines or scratches on a surface inscribed by another object passing over that surface
Usually tool marks made by a tool passing over a hard surface; can be a tool or object; can be striation marks on bullet surfaces from rifling on barrels of firearms
After recognition of the impression marks, what is the next step?
Documentation
Photographs should show:
location of the impression in the scene (overall and mid range photos)
impression with an evidence marker next to it (close up photos)
comparison quality photographs may replace/ supplement cast
Comparison Quality Photographs
- film plane parallel
- scale at same depth as impression
- side light technique for indentations
- bracket exposure
What is the best way to collect an impression?
Take the entire item when possible
If taking the entire item is not possible or necessary
lifts and casts are used for impression evidence
Collection and Preservation of Impressions
- tape lifts
- gel lifts
- accutrans
- mikrosil
- electrostatic dust lifter
- casts (plaster of paris, dental stone)
Comparison Specimens: Footwear
Some has to wear the suspected shoe, somewhere
Comparison Specimens: Tire marks
The suspected tire should be on the suspected care, somewhere
Comparison Specimens: Friction Ridge Impressions
- rolled ten print card
- major case record
- barefoot impression
Comparison Specimens: Fire arms
test fire with suspected weapon and ammunition
Patterns may be difficult to analyze or compare because of:
poor visibility; lack of medium; interference between pattern evidence and complex background
Photographic Techniques
Side lighting
UV light
ALS
Filters
Physical and Chemical development techniques
luminol/ blue star
amido black
leucocrystal violet
digital imaging
photo shop
image pro
Questioned document
any means of communication that is suspect, entirely or in part, as to authenticity of its origin
With questioned document, it can examine and compare:
handwriting, typewriting, copier output, looking for erasures, looking for alterations, sequence of writing and printing
alteration
a change in the physical appearance or meaning of something, often only slightly
authenticate
to prove that something is real, true, or what it is purported to be
forgery
to make an illegal copy of something in order to deceive
examination and comparison of handwriting is
scientific and technical
Questioned document examination
starts with basic handwriting style; handwriting style and major characteristics are set by the time formal education is finished
Question document examination class characteristics
may see similarities in people from the same countries
Question documentation examination individual characteristics
normal variations
Three basic parts associated with a document that can yield useful information
- the writing surface
- the writing instrument
- the transfer medium
Writing Surface
paper - most common
expensive or cheap?
high content of cotton fibers
surface treatment (coating or sizing)
mechanically pulped or chemically pulped wood
Writing Instrument
Ball point pens (different mechanics of pens; ball point INK)
ink delivery varies from pen to pen
ink compositions
Evidence (questioned) and control (known) samples must be:
in a sufficient amount = lots of control samples
pristine condition
original writings
not copies
Known standards for a questioned document
collected writing; requested ordered writings
Collected writings
must useful knowns; most difficult to obtain; samples of subjects life experience and history; original writing preferred; must be authenticated
Requested (ordered) writings
voluntary; court order; direct from the subject; carefully controlled conditions (sample writing must be dictated to subject; no spelling grammar corrections; should take upwards 20-30 samples of the sam dictation
Writing mechanics
how a letter is written; letter shapes; connections between letters; where pressure was applied; word and letter spacing; other subtle characteristics of the writing
Handprinting
non cursive writing; letters are individually formed; not normally connected
Daubert Issues w/ Questioned Documenti Examination
Handwriting comparison and identification has been accepted in the legal system for about 100 years
Questioned whether or not is it actually scientific or technical
may be accepted or may be challenged
FBI
Footwear and Tire tread Database (manufacture information, previously submitted case information)
NIJ
TreadMark; SoleMate; TreadMate
