Forensics uses various scientific disciplines to gather and analyze evidence from crime scenes. These include anthropology, crime scene investigation, criminalistics, engineering, entomology, medicine, odontology, psychology, and toxicology. Forensic techniques analyze evidence like DNA, fingerprints, firearms, documents, trace evidence, and voice/sound recordings to help solve crimes. Proper collection, documentation, and chain of custody of evidence at crime scenes is important to preserve its admissibility in court.

1. What is Forensics?

2. 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”.

3. 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.

4. Disciplines in Forensics
• Crime Scene Investigation –
gathering information at a crime
scene, collect and preserve
evidence
• Criminalistics – collect, identify, and
analyze physical evidence from a
crime scene

5. Disciplines in Forensics
• 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

6. Disciplines in Forensics
• 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

7. Disciplines in Forensics
• 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.

8. 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

9. 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.

10. 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

11. 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

12. Forensic Techniques
Forensic Chemistry
identify and analyze toxic substances,
fire accelerants, gunpowder residue,
explosives and other chemical
substances

13. 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

14. Forensic Techniques
Forensic Serology
identify blood and other body fluids

15. Forensic Techniques
Impression evidence
study various types of markings on
evidence, such as footwear
impressions, tire impressions, and
footprints

16. 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

17. 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

18. 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

19. Forensic Techniques
Voice Analysis
ties unknown voices in recorded
messages to particular speakers
based on speech patterns that are
unique to every individual

20. 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.

21. 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

22. 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.

23. 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.

24. 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.

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

26. 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

27. 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