physical methods in forensic science final

physical evidence (from chapter 1)

any and all relevant material/objects associated with a crime scene, victim, or witness

crime scene management

securement, protection, and documentation of scene

evidence management

correct sampling and storing process

1st responders at the scene are required to offer BLANK to any injured persons

assistance

crime investigators are responsible for

preserving the crime scene and minimize access to the scene to avoid contamination

things 1st responders need to document

state of scene and existing conditions upon arrival

identity of all personnel at scene

statements/actions of everyone there

any items that may have been moved and who did it

to preserve the scene there must be

an initial boundary larger than the scene

a single path in and out

log of who enters and exits

PPE that should be worn

nitrile gloves (two pairs & change often)

safety glasses and face shield

dust mask, air purifying respirator or self-contained breathing apparatus

disposable synthetic coveralls and show covers

note taking begins with 1st responders and must be BLANK

recorded in chronological order

note taking errors CANNOT be

erased or torn out

notes should include (part1)

day, date, & time

name of people present at time of arrival

detailed description of location of items of physical evidence recovered

time and location of recovery of item and by whom

who reported incident, time and date of reporting, and exact location of scene

notes should include (part 2)

weather conditions

what the incident was

activity at scene since the main incident occurred

lighting conditions at night

officer in charge

log of people going in and out

photographs must be BLANK

unaltered and nothing should be moved

3 shot rule

overall shot

mid-range shot

close-up shot

photographing a dead body

mid-range shot to show body’s position and location

close-up shot to show injuries on body and weapons lying near

things needed in photo log

date and time

camera setting (F-stop, shutter speed, special lighting, etc)

camera make, model and serial number

file name and exposure number

type of shot

distance of the subject

brief description of subject

sketching documents BLANK

give perspective and distance

rough sketches are done at the scene and are BLANK

not drawn to scale

rough sketches contain

all essential info and measurements at the scene

finalized sketches are precise and computer designed diagrams of the crime scene that is BLANK

suitable for courtroom use

measurement techniques for measuring tape

triangulation method

baseline method

polar coordinate method

triangulation method and baseline method are best used in a

closed space

polar coordinate method is best used in a

open space

videography uses same principles of photography BUT

videos do not replace photos, they compliment them

good search method for open crime scene

spiral, strip or line, & grid

good search method for indoor crime scene

quadrant or zone

evidence you look for in a homicide case

weapons, bullets, cartridges, & cross-transfer evidence

evidence you look for in an arson case

accelerant & ignition device

evidence to look for in a burglary case

toolmarks, broken glass, blood, fingerprints, & shoe prints

evidence to look for in pedestrian hit-and-run

cross transfer on both the vehicle and pedestrian

questioned sample (unknown)

collected at scene

trace evidence

normally extremely small

known sample (reference/standard)

collected from a known object

substrate control

uncontaminated surface material

proper order to collect evidence with value and fragility in mind

1. non-fixed trace evidence

2. sequence chosen to avoid contamination

3. development of latent prints

the goal when packaging evidence is to BLANK

protect and preserve evidence

tips for packaging

package each item separately

completely seal package

trace evidence shouldn’t be removed from anythig

paper envelopes are used for

trace evidence

air-tight jars sealed with tape are used for

small liquid samples

new paint cans with air tight seals are used for

large liquid samples & charred debris

wet blood must be BLANK before collected in paper envelop

dried

chain of custody is written on each piece of evidence and it holds a BLANK

chronological record of each person who handled/examined the evidence

removal of evidence must comply with the

4th amendment

search warrants

legal court orders which, upon establishment of probable cause, permit an exception to the 4th amendment

arrest warrants

legal court orders declaring there is probable cause to believe that the person to be arrested has committed a crime

exceptions to 4th amendment

border searches

consent searches

search incident to arrest

plain view

emergency/exigent circumstances

open fields

stop and frisk

vehicle inventories

steps that labs must follow

1. accreditation by profession organizations

2. credentials established as forensic laboratories

3. findings widely accepted (GOAL)

3 distinct phases of the role of forensic science in the investigation of a crime

1. recovery of evidence from crime scene

2. forensic examination of the recovered evidence

3. presentation of scientific test results in court

types of evidence

physical evidence

documentary evidence

demonstrative evidence

testimony

physical evidence

tangible objects; items that are real, direct, and not circumstantial

examples of physical evidence

weapons, trace evidence

documentary evidence

any kind of writing, sound, or video recording, its validity is usually authenticated by expert testimony

examples of documentary evidence

transcript of recorded telephone convo

demonstrative evidence

real evidence used to illustrate, demonstrate, or recreate a prior event

example of demonstrative evidence

cardboard model of the crime scene

testimony

evidence in the form of witnesses speaking under oath in court

examples of testimony

eyewitnesses, hearsay, and character witness

characteristics of physical evidence

identification

comparison

identifications

1. adopts testing procedures to give characteristic results for specific standard materials

2. one identity has been established they may be permanently recorded and used repeatedly to prove identity

comparison

1. suspect specimen and standard/reference specimen go through same tests and examination

2. determine whether or not specimens have common origin

individual characteristics

evidence that can be associated with a common source with a high degree of probability (can narrow down to a single origin)

class characteristics

evidence that can be associated only with a certain group and NEVER with a single source (broad characteristics)

toolmarks happen when BLANK

a tool creates an impression, cut, scratch, or abrasion on another surface

toolmark identification is done by BLANK

casting

photos needed to be taken of impressions

overall shot

mid-range shot

close up shot

2D impressions are lifted by

clear tape

electrostatic lifting

3D impression are casted using

silicon rubber

dental stone

active bloodstains BLANK

travels because of force

examples of active bloodstains

impact stains

arterial breach

cast-off

tail of bloodstains indicates BLANK

the bloods’ direction of travel

transfer bloodstains are on surface and are a result of BLANK

direct contact with an object that has wet blood on it

examples of transfer bloodstains

bloody foot prints

point of convergence

a line drawn down the middle of the long axis of multiple spatters may result in identifying the place from where the blood originated

point of origin

when multiple bloodstains appear to have originated in the same place, investigators can find its origin

passive bloodstains form as a result of BLANK

gravity

examples of passive bloodstains

drops

blood pool

blood flow

the higher the blood drops =

larger diameter of blood drops

through analysis and interpretation of evidence, we gain the following

corpus delicti

modus operandi

link suspect with victim/scene

disproving or supporting

identification or elimination

providing investigative leads

evidence must be

1. probative

2. material

probative

actually proves something

material

addresses an issue that is relevant to the particular crime

distinction between BLANK and BLANK determines its admissibility and its probative value

relevant and irrelevant

Daubert Ruling (1993) is the BLANK

worldwide standard

admissibility is determined by

scientific evidence/technique can be, or has been tested

theory/technique has been subjected to peer review

potential rate of error is known

standards can verify the theory/technique

technique has been accepted by scientific community

5 main stakeholders in courtroom

prosecutor

defense

forensic scientist

judge

police officer/detective

layperson’s testimony

factual & never contain personal opinions

expert testimony

states opinion

no absolute certainty

based on reasonable scientific certainty

advocate for truth, not one part

the court qualifies the expert through voir dire which includes

counsel emphasizes expert’s ability & expertise

opposing side cross-examines expert, to try and emphasize any weakness

to have a case there must be an MMO, which is

motive

means

opportunity

motive

reason to do the crime

means

ability to do the crime

opportunity

can be placed at crime scene

properties of glass

hard, amorphous, brittle

transparent

made by fusing silica (sand) with other oxides

types of glass

soda lime glass

pyrex glass

leaded glass

tempered glass

laminated glass

soda lime glass

most common type of class

fused silica with sodium carbonate & either calcium carbonate or lime

pyrex glass

shock & heat resistant

vehicle headlights

adds boron oxide

leaded glass

lead (II) oxide included

sparkles

used in fine glassware & glass art

called crystal

tempered glass

rapid heating & cooling

stronger than ordinary window glass

forms “dices”

used for side & rear car windows

laminated glass

high strength vinyl plastic sheet between 2 sheets of ordinary glass

windshields

multiple layers for bullet proof glass

glass is encountered in these crime scenes

breaking & entering

hit-and-run

assault