FRNSC410 Midterm #1

trace

the track made by the passage of any person or thing

fracture

separation of object or material into pieces under action of stress

direct physical fit

Separated pieces juxtaposed and associated (jigsaw fit); separation process random and material malleable to production of random characteristics

indirect physical fit

separated pieces cannot be juxtaposed, with the separation process not random and relies on surface/internal characteristics of pieces

identification

classification of object into groups sharing common features and properties

individualization

illustration of uniqueness of objects, different from others, due to unique features

# loci CODIS uses

20

secondary transfer

fragments transferred from A to B to C

unrelated transfer

fragments may transfer before and after event that are unrelated to event

associated

an inference of contact between objects, the source of the trace, and the substrate on which it was found

physical record

totality (assemblage) of traces created during event

artifacts

something observed in a specific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure

event reconstruction

ordering of actions in relative space and time based upon analysis of physical record

pareidolia

tendency to perceive a specific, often meaningful image in a random or ambiguous visual pattern

science

intellectual and practical activity encompassing systematic study of structure and behavior of physical and natural world thru observation and experiment

scientist

person who is studying or has expert knowledge of one or more natural or physical sciences

experimental science

creation of hypothesis testable in controlled laboratory conditions

historical science

explanation of unobserved cause of past event based upon observation of persistent traces

pseudoscience

collection of beliefs or practices mistakenly regarded as based on scientific method

enthusiasm

intense and eager enjoyment, interest, or approval

enthusiast

person highly interested in particular activity or subject

pseudoscientist hallmarks

impenetrability, ulterior motives, lack of formal education and training

confirmation bias

preference toward information that supports hypothesis, selectively collection addition evidence, and interpreting evidence in biased manner

congruence bias

testing of hypothesis without considering alternate hypotheses

education

theory, general concepts, learning to learn, preparation for unknown problems

training

skills, specific tasks, learning to perform, preparation for known functions

fabrication

invention of data or results

falsification

willful distortion of data or results

Brady v Maryland

requires prosecutors to disclose materially exculpatory evidence in government's possession to defense

curtilage

are immediately surrounding dwelling; counts as part of home for many legal purposes including searches and self-defense laws

consent to search

must be given voluntarily by someone with authority

third party consent

someone with unrestricted access to property

apparent consent

investigators believe person has proper authority

implied consent

person "gives" consent through reporting of crime

exclusionary rule

evidence obtained in violation of 4th amendment will be suppresssed

initial response of first responders

safety, emergency care, scene boundaries, transfer scene control, document all actions

scene boundaries

establish boundaries from focal point extending outward to include location of event, potential points/paths of exit/entry, and locations of victim and traces

investigator in charge

varies depending on jurisdiction, but is the case/investigating detective or other LEO, or the crime scene investigator

1st step of scene assessment

debrief first responders, evaluate safety issues, search warrant is in hand, evaluate path of entry/exit and initial boundaries, determine # and size of scenes and prioritize, and establish secure area for equipment/consulation

2nd step of scene assessment

establish secure area for storage of evidence, request any additional resources, ensure continued scene integrity, identify potential witnessess/gather IDs, canvas surrounding area, prelim documentation/photography of scene

contamination control

limit access to people directly involved in scene investigation tasks

prioritize collection of evidence

systematic search pattern based upon size and location of scenes

QA (quality assurance)

written guidelines that cover all aspects of lab from safety to personnel requirements; establishes a minimum standard of operation

QC (quality control)

specific methods of implementation of QA guidelines

CSI unit accreditation standard

17020:2012 gives requirements for the operation of various types of bodies performing inspection

crime lab accreditation standard

17025:2017 gives general requirements for the competence of testing and calibration laboratories

certification organizations

IAI, ABC

moistened swabs

useful for dry blood and other biological stains

dry swabs

useful for liquid/wet blood and other biological stains

swab packaging

in paper then sealed with tape, I&D

scraping usage

good for large specimens or those that are dry/flaking

scraping packaging

stored in a paper fold, then labeled, sealed, and I&D

reference sample

representative samples from objects/locations used for comparison to questioned specimens/samples

evidence authentication

identification of object offered that establishes that it is purported as such and the condition of the object

zone search

appropriate for scene with discernible zones, with each zone searches at least 2x with 2 people/search; best for indoor areas

point to point search

Move in order of appearance of evidence (from #1 to #2, #2 to #3, etc)
Often disorganized, trace evidence may be overlooked

circular search

one criminalist searches clockwise from waist-level to ceiling, while the other searches counterclockwise from waist-level to floor then they switch

outdoor search techniques

circle, point-to-point, wheel, line, and grid

wheel/ray search

from focal point, radiate outward in straight lines; not useful for large areas

line search

start at one end and finish at opposite end, maintain equal distance between searchers

strip search

search in one direction, then at the end move over and double back to start and continue until finished

grid search

A search method employed by two or more people overlapping separate line searches forming a grid.

reconstruction

identification and sequencing of actions to assist in reconstruction of an event under investigation and MUST be done by generalists

action

interaction of 2+ objects

event

totality of actions

passive documentation

before significance of the evidence is known

active documentation

significance is recognized

generalist

broad schooling of crime, criminals, and science

specialist

trained in a specific specialty

holistic crime reconstruction

development of actions and circumstances based on the system of evidence discovered and examined in relation to a particular crime

scientific fact

determined through careful examination using scientific method

legal truth

determined by the trier of fact based on their understanding of the law

forensic scientist

educated and trained to examine and determine the meaning of physical evidence with the expectation of presenting their findings in court

criminalistics

the recognition, classification, examination, and interpretation of physical evidence using the natural sciences, logic, and critical thinking

accuracy

the agreement between a measurement and its true value

precision

the reproducibility of several measurements

systematic errors

result from defects in and improper use of measurement devices; usually produces inaccurate but precise results

random errors

vary widely and are not reproducible, typically the result of alignment and parallax issues when reading scales; usually produce inaccurate and imprecise results

traceable tools

tools whose graduations have been calibrated against a traceable standard done by an entity accredited by NIST

UV light

10-400 nm

visible light

400-700 nm

IR light

700-10^6 nm

red light

647-700nm

orange light

585-647 nm

yellow light

575-585 nm

green light

491-575 nm

blue light

424-491 nm

violet light

400-424 nm

luminescence

emission of light at low temperatures

blood

doesn't luminesce under any wavelength; absorbs UV, VUS and IR with Amax= 415 nm

UVA

315-400 nm; smallest energy

UVB

280-315 nm

UVC

180-280 nm; largest energy

near (long-wave) UV light

300-400 nm

mid (short-wave) UV light

200-300 nm

long-wavelength lamp

central wavelength is 365 nm

short-wavelength lamp

central wavelength is 254nm

NIR (near IR)

700-1400 nm

SWIR (short wavelength IR)

1400-3000 nm

MWIR (mid wavelength IR)

3000-8000 nm