What is forensics

What is Forensics?

What is Forensics?

• a special discipline that is used to discover the facts about what happened during a crime.

• A dictionary calls it “science in the service of law”.

Disciplines in Forensics

• Anthropology – examine bones to identify remains and determine other information such as age, race, and gender

• Art – identify missing children, victims, or suspects through reconstructive techniques based on age progressions, composite imagery and knowledge of human anatomy.


• Crime Scene Investigation – gathering information at a crime scene, collect and preserve evidence

• Criminalistics – collect, identify, and analyze physical evidence from a crime scene


• Engineering – determine material or structural failures and reconstruct events such as accidents or collapse of buildings

• Entomology – study insects found on a decomposing body to determine time of death

• Jurisprudence – study philosophy of law


• Medicine (Pathology) – study injuries and disease to determine cause and manner of death through an autopsy

• Odontology – dentists that identify human remains by matching dental records, and identify bite marks


• Psychology & Psychiatry – study human or criminal psychology and behavior, and profile criminals and victims

• Toxicology – identify and analyze poisons, drugs, and chemicals and study their effects.

Evidence

• any tangible material that can be used to prove the facts of a matter in a court of law.

• Expert witness: someone who testifies in court as a qualified expert in a particular subject area

Criminalistics

Criminalistics involves analyzing all of the evidence that is collected at a crime scene. There are many subtopics that can all be considered under the heading of Criminalistics.

Forensic Techniques

DNA Analysis

use molecular biology to extract and analyze DNA from blood, semen,

bones, body tissue, hair roots, saliva, fecal matter, and any other

material

Forensic Techniques

Firearms Examination

analyze firearms, discharged bullets, cartridge cases, shotgun shells, unusual or homemade weapons,

and ammunition components. They determine what kind of weapon fired

a bullet, match bullets to specific weapons, and determine the

trajectory and distance of a shot

Forensic Techniques

Forensic Chemistry

identify and analyze toxic substances, fire accelerants, gunpowder residue,

explosives and other chemical substances

Forensic Techniques

Forensic Drug Analysis

analytical chemistry is used to identify the presence and quantity of

controlled substances. A drug chemist analyzes unknown powders,

liquids, plants, pill, capsules, and other forms of drug

Forensic Techniques

Forensic Serology

identify blood and other body fluids

Forensic Techniques

Impression evidence

study various types of markings on evidence, such as footwear impressions, tire impressions, and footprints

Forensic Techniques

Latent Fingerprints

latent fingerprints are invisible to the human eye. Fingerprints are detected, developed, and processed in order to compare them to known fingerprints for identification

Forensic Techniques

Questioned Document Examination

scientific examination of handwriting, typewriting, printing, photocopying, or other mechanical production of written material. Identify ink, paper, or other document components for authenticity, forgery, or alteration

Forensic Techniques

Trace Evidence

examine hair, fibers, glass, soil, plants, minerals, and many other different types of materials. Substances are studied under a microscope and chemical techniques can be used to identify and individualize evidence even when found in very small quantities

Forensic Techniques

Voice Analysis

ties unknown voices in recorded messages to particular speakers based on speech patterns that are unique to every individual

What happens at a crime scene?• The first responding officer must secure

and protect the integrity of the crime scene. This is a very important task! Sometimes crimes cannot be solved and criminals are set free because the crime scene was not properly processed.

• The first responding police officers will then state their findings to the criminal investigators, the CSI team.

Things that the CSI team does:• Gather information• Search for evidence• Document evidence• Collect evidence• Preserve evidence so it remains exactly

as it was when found at the scene• Conduct field tests• Reconstruct the sequence of events

Investigators cannot make up theories or guess about what happened at a crime scene.

They must use logical reasoning to form a testable hypothesis that they will either prove or disprove based on evidence.

Chain of Custody

• the collection, labeling, and testing of evidence. There must be a documented trail of exactly who has handled the evidence from crime scene to court. If the chain of custody is broken because of improper handling or labeling of evidence, then the evidence may not be admissible in court.

Primary vs. Secondary Crime Scenes:The primary crime scene is the location where the crime was committed such as a homicide or a robbery. A secondary crime scene could be the location where a murder victim was buried, the victim’s home where evidence of the assailant is found, or a suspect’s home where fibers from the victim’s clothing or hair were found. In order for a location to become a crime scene, there must be evidence found at that site.

Walk-through

• scan the entire area and make some observations in order to get the big picture.

Things they look for during the walk-through• Type of crime scene

(primary/secondary, indoor/outdoor, etc)

• Physical boundaries• Types of evidence present• Points of entry and exit• Damage

Documenting a crime scene:• Take notes – description of scene,

victim, investigators, and observations such as weather conditions, windows broken, stains, etc.)

• Videotape and Photograph• Draw a Scale Diagram

Education

What is forensics