Forensic science is the application of science to address legal questions. It involves using scientific methods and techniques to investigate and establish facts in criminal or civil cases. Forensic science assists in criminal investigations by analyzing evidence scientifically to help identify individuals, reconstruct events, and determine causes of injuries or death. Some key branches of forensic science include forensic pathology, anthropology, odontology, serology, toxicology, and questioned documents.

1. INTRODUCTION TO FORENSIC
SCIENCE

2. DEFINTION
 Forensic science describes the science of associating
people, places, and things involved in criminal
activities; these scientific disciplines assist in
investigating and adjudicating criminal and civil
cases.
 “Science” is the collection of systematic
methodologies used to increasingly understand the
physical world.
 The word “forensic” is derived from the Latin forum
for “public”.

3.  More technically, “forensic” means “as applied to
public or legal concerns.”
 Together, “forensic science” is an apt term for the
profession of scientists whose work answers
questions for the courts through reports and
testimony.
 Important terms: mens rea, actus reus, modus operandi.

4. BRANCHES
 Forensic Pathology
 Forensic Anthropology
 Forensic Odontology
 Forensic Serology
 Toxicology
 Behavioral Sciences
 Questioned Documents
 Other Specialties (Forensic Microbiology, Forensic
Engineering, Wildlife Forensics, Cyber Forensics)

5. How does forensic science work?
 Criminal Case occurs
 Lawyers: “This is what happened . . .”
 “How do they know?” = Forensic Science
 Forensic science finds and analyzes the evidence based
upon scientific principles.
 Scientists interpret the evidence – prosecution vs defense.
 How reliable is the evidence?
 To what extent can the evidence be trusted?
 How common is procedure used to analyze evidence.
 Is procedure widely accepted by scientific community?

6.  Is procedure accepted by “common” person in jury –
must convince jury of validity of the science when
they do not have a science background.
 DNA is considered very reliable.
 Prosecution and Defense each present their evidence
to “make their case”.
 Evidence presented in court Experts Eyewitnesses
Police.
 Judge or jury gives a verdict based on information
presented.
 Presumption of innocence until proven guilty
beyond a reasonable doubt.

7. What does forensic science do?
 1. Reconstruct past events Reconstruct sequence of
events to build a “story” about what happened.
 2. Link suspect with crime scene.
 3. Decide charge in a case Murder or accident.

8. Question
 Forensic science means:
 A) Knowledge of medicine and crime
 B) Application of medicine knowledge to law
 C) Application of basic sciences to judiciary
 D) Court of law

9. Question
 Which branch of Forensic Science deals with
spurious contaminated viscera samples?
 A) Serology
 B) Toxicology
 C) Pathology
 D) Anthropology

10. Principles and Laws of Forensic Science
 Locard’s Principle of Mutual Exchange.
When two entities come in contact there is mutual
exchange of matter.
 Principle of Individuality
Individuality implies that every entity, whether person or
object, can only be identical to itself and so is unique. No
two objects whether natural or artificial can be exactly
the same.
 Law of Analysis
The quality of any analysis is determined by the quality of
the sample under analysis, the chain of custody, and the
expertise of the individual who analyses it.

12.  Law of Circumstantial Facts
This is concerned with eyewitness testimony, victim
statements, and so forth. Anytime that people are
called upon to provide evidence there is a chance
that the evidence they supply is not accurate. This
can be unintentional e.g. through mistaken
observations, making assumptions or deliberate e.g.
lying or exaggerating. On the contrary, evidence
which gives a factual account e.g. based on
investigation and evidence has a higher chance of
being accurate and is more reliable.
 Law of Comparison
At all times, likes should always be compared with
likes.

13.  Law of Progressive Change
Different objects change, although they may change across
different time spans. For example, blood samples will
eventually degrade. Some objects are more durable than
others and may be relatively permanent, remaining
mostly unchanged during identification.
 Law of Probability
Conclusions drawn from forensic analysis are dependent
on the method used and its advantages and
disadvantages. All this has to be taken into consideration.