Forensic Science Review

Flashcards covering the definition, scope, crime labs, services, functions, and other services in Forensic Science.

Forensic Science

The application of science to criminal and civil laws enforced by police agencies in a criminal justice system.

Criminalistics

A section of forensic science dealing with the analysis of physical evidence from crime scenes.

Federal Crime Labs

FBI maintains the largest crime laboratory; DEA analyzes drugs; ATF analyzes alcohol, firearms, and explosives; US Postal Inspection Service handles postal-related crimes.

Regional or Satellite Labs

Labs operating under a central facility, providing services to nearly the entire state.

Physical Science Unit

Applies chemistry, physics, and geology principles to identify and compare crime-scene evidence.

Biology Unit

Staffed with biologists and biochemists, identifies DNA profiles on bodily fluids, compares hair/fibers, and identifies botanical materials.

Firearms Unit

Examines firearms, bullets, cartridge cases, shotgun shells, and ammunition.

Document Examination Unit

Studies handwriting and typewriting on documents to ascertain authenticity and source; analyzes paper, ink, and other alterations.

Photography Unit

Examines and records physical evidence using digital imaging, infrared, ultraviolet, and x-ray photography.

Toxicology Unit

Examines body fluids and organs to determine the presence/absence of drugs and poisons.

Latent Fingerprint Unit

Processes and examines evidence for latent fingerprints.

Polygraph Unit

Also known as lie detectors, used by criminal investigators.

Voiceprint Analysis Unit

Transforms speech into a visual display called a voiceprint to tie a voice to a suspect.

Crime Scene Investigation Unit

Dispatches personnel to crime scenes to collect and preserve physical evidence.

Functions of the Forensic Scientist

Using the scientific method to test a hypothesis; evidence is free from bias.

Forensic Psychiatry

Area where the relationship between human behavior and legal proceedings are examined.

Forensic Odontology

Helps identify victims by analyzing teeth; also analyzes bitemarks to identify perpetrators.

Forensic Engineering

Failure analysis, accident reconstruction, and determining the causes/origins of fires or explosions.

Forensic Computer and Digital Analysis

Identification, collection, preservation, and examination of information from computers/digital devices.

2.1: Processing the Crime Scene

Securing and Isolating the Crime Scene

First officer arriving is responsible for preserving and protecting the area as much as possible

Keep note of people or vehicles leaving the scene

First priority given to obtaining medical assistance for those in need

Then, extensive efforts to exclude all unauthorized personnel

Once additional officers arrive, boundaries should be put into place, starting with center of scene and covering any entry/exit paths, anywhere that evidence could be discarded or discovered

Seal off area with ropes, barricades, tape, and officers on the scene

Keep logs of who enters and exits scene, family not permitted

Once secured, lead in investigator starts evaluating the area

First determines boundaries of the scene and establishes perpetrators path of entry and exit

Obvious items of evidence must be documented and photographed

Investigator then proceeds with an initial walkthrough of the scene to gain overview of situation and develop a systemic strategy for examining and documenting crime scene

Personnel should leave the crime scene completely as is, not eating, smoking, opening or closing windows or doors, touching the thermostat, leave any water running, do not touch the body, etc

Recording the Crime Scene

The three biggests ways to record the crime scene is note-taking, sketching, and photography

Ideally all three should be done, but cost restrictions leads to photography not always happening

Follow bullets are about notes and note-taking

Notes begins with the call to the scene, starting with identifying the preston who contacted the investigator, time of contact, and any preliminary information including case number

Upon arrival, record the date and time of arrival, who is present, and identities of any other personnel who are being contacted (name, title, and time of arrival)

Musat interview first responding officer to track movements throughout the scene, as well as record the tasks assigned to each member

Prior to sketching, photography, or searching, lead investigator must dfo an initial walk through

Take notes on many aspects of crime scene in original condition

Once a search for evidence has taken place, team members mark the location of all evidence and fully describe in notes

Also, body must be examined before medical examiner or coroners move it

Audio-recordings is another good option as it leaves hands open for more tasks and speaking is faster than writing

Can record the scene with a camera, but video needs to be transcribed later

Following bullets are about photography

Crime scene must be unaltered for photographs, unless injured people are involved

Objects cannot be moved or touched until they have been photographed from all angles

If moved, position changed, or items added, it may not be admissible in court

If an item has been moved or removed before photography, it must be noted and can not reenter the crime scene for photographs

Can not be used as standalone evidence, they’re complementary to notes and sketches

Photography also important for documenting biological evidence in its original condition

Digital photography has advantage of:

Ability to observe images immediately after taking them, ensuring they show best possible detail

Photographs should record the area in which the crime took place and all adjacent areas

Most Important for it to be unaltered

Should be photographed in logical succession, starting from overall scene and working down to individual pieces of evidence the jurors in the trial use

CSI’s usually use a digital single-lens reflex camera (DSLR)

4 minimum photos required at a crime scene are:

Overview photograph

Medium-range photograph

Close-up photograph

Close-up photograph measurement scale, such as a ruler

Overview photos of the entire scene (including entry and exit) are taken first

Taken from outside the borders of the scene and from various angles

If there is a body, they must show the body's position and location relative to entire scene

Medium-range photographs show the layout of smaller significant areas of the crime scene

Taken with evidence markers in place to show spatial relationships

Include at least one photograph of the ‘center” of the scene

If there is a body, it usually includes the site where the victim was found and the surrounding area

Close-up photographs are taken last and show greater detail of individual objects or evidence

Taken ata 90 degree angle at first, with scales and markers (getting as close as possible without affecting anything)

Videotaping Crime Scenes

Must include overview, medium-range, and close-up images

Sketching the Crime Scene

Clearly show the layout of the crime scene and illustrate the relationship in space of all significant items and features

Clarify objects in photos or in notes

They show measurements over long distances and topography of outdoor scenes

Topography: the arrangement of natural and artificial physical features of an area

Highlight possible points of interest, movement, entry, and exits

The rough sketch should include accurate depiction of the dimensions of the scene and location of objects

Includes:

Title block with information on the case, crime scene, and person creating the sketch

Length with identity and dimensions of objects in the sketch

Compass showing the north direction

Body containing the sketch itself

Finish sketch is drawn to scale with care and concern

Most use CAD software to help draw them out

Searching the Crime Scene

First walkthrough pinpoints entry and exit points and perpetrators possible path

Obvious items of evidence are located and documented

The conditions of the scene are observed and recorded

Many different search patterns and the one chosen depends on the details of the specific case

Search patterns:

Line/Strip Search Pattern

One or two investigators start at the boundary of the crime scene and search in straight lines across to the other side of the crime scene

Grid Search Pattern

Two or more investigators form a grid by searching in line patterns that overlap and are perpendicular to each other