Crime Scene/Crime Lab (Chapters 9 & 10)

Crime Scene

Contains the most evidence in conducting a criminal investigation

Responding Officer

Controls crime scene & doesn’t allow contamination

Contain

No bodies or objects can be removed unless absolutely necessary

Plastic

Imprinted into and onto other material (gum, putty, new paint – concrete)

Latent

Oil, dust, blood, other contaminants on fingers, palms, etc that leave behind print on clean surface – do to ridges on your skin

Cold Hands

Means less chance of print

Methods to Identify a Print

Dusting, iodine, fuming, laser technology

40%

Percent of crime scenes that have fingerprints

Blood Stains & Spatters

Reconstruct crime scene, tells direction, velocity, angles, Gunshot wounds

Footprints and Tire Treads

Where appropriate, photographs and casts should be made

Etching

Serial numbers, VINs, part/model numbers

Documentation

Handwriting/Printers/Paper/Photos/Photo Geolocating

Crime Labs

Used to analyze physical evidence through biology, chemistry, physics, Discover, collect and preserve physical evidence, chain of custody, security

Miranda (1966)

Basis for increased need for crime labs

Forensic Science

Application of science to criminal & civil laws that are enforced by law enforcement

Criminalists

Physical evidence analysis, Provides answers to how, when, where and how many people committed crimes

First Crime Lab

Los Angeles Police department in 1923, FBI in 1932, popular in ‘70s

Investigators

Need to understand what (and which) labs can do for them

Direct

Testimony

Indirect

Physical or circumstantial

Testimonial

Witness account

Documentary

Written

Physical

Proof

Physical Science Unit

Technical & diverse

Biology Unit

Fluids/blood/hair/DNA

Firearms Unit

Guns & ammo

Documentation Unit

High tech analysis of all documents, handwriting

Photography Unit

Photos, infrared, ultraviolet , Xray photos, infrared, ultraviolet , Xray

Toxicology Unit

Presence of drugs or alcohol in blood, breath

Voice Analysis Unit

Cases involving telephone threats or tape-recorded messages

Evidence Unit

Incorporating crime scene evidence collection into the total forensic science service

Latent Fingerprint Unit

Responsibility for processing and examining evidence for latent fingerprints

Polygraph Unit

Its functions are handled by people trained in the techniques of criminal investigation and interrogation

DNA

1980s game changer and typically used in murder and/or rape cases

Combined DNA Index System

CODIS

Baseline

Coordinate sketches used to pinpoint the location or objects or evidence

Body Fluids

Bloodstains, semen, vaginal fluids, saliva, urine, perspiration, pus, and human milk

Cross-Projection Sketches

Provides a three-dimensional view of a scene from above with the walls folded down

Latent Descriptor Index

Searches the division’s automated files based on latent fingerprint pattern types, physical description information, and case information

Photo Log

Date, photographer’s name, type of camera, lens, film, case number, and a list of every photograph taken

Scene Investigator

Key person involved in conducting the preliminary examination of the crime scene and then decides whether to continue the investigation

Secretors

80% who have in their other body fluids detectable amounts of the same ABO group characteristics as are found in their blood

Triangulation

Uses two or more reference points to establish the position of an object

Witness Photos

Overall pictures showing the crime scene as observed by a witness

Spiral Method

Starting on the outside and moving toward the center

Radial Method

Searches begin at the center of the wheel and proceed outward

Grid Method

Search is repeated from side to side

Zone Method

Divides the crime scene and assigns different investigators to each

Forensic Science Information Resource System

Started in 1985 to offer information services to personnel in the FBI laboratory division and to state and local crime lab personnel throughout the United States

Comparison Microscopy

Allows two objects to be viewed side-by-side simultaneously through a single eyepiece

Stereoscopic Microscopy

Allows users to view three-dimensional objects at low magnification levels

Thin-Layer Chromatography

Technique used to separate the components of a mixture

Spectrophotometry

Method to measure how much a chemical substance absorbs light

Mass Spectrometry

Analytical technique that is used to measure the mass-to-charge ratio of ions

Low-Tech Equipment

Shoot tank, Trigger pull determination instrument, Bore light, Vacuum sweeper, Balances, Assorted tools

Central Laboratory

Concentrates its services in a specific location convenient to the majority of its users

Regional Laboratory

Serve areas that are geographically large and have small populations

Accreditation

A third-party assessment that an organization meets certain standards