This presentation is a study material for the forensic aptitude and caliber test (fact and fact plus examination). This contains the topics Principles of forensic science and disciplines of forensic science. For the educational video please go to the link https://youtu.be/VBpgshoOQR4

1. PRINCIPLES OF
FORENSIC SCIENCE

2. FORENSIC SCIENCE
“Scientific discipline which is directed to the
recognition, identification, individualization and
evaluation of physical evidence by the application
of all principles and methods of natural sciences
for the purpose of administration”

3. FORENSIC SCIENCE
Term forensics is derived from the latin word
‘forensis’ which means ‘the forum’

4. PRINCIPLES OF FORENSIC SCIENCE
7 basic principles and laws
1. Law of Individuality
2. Principle of Exchange
3. Law of Progressive Change
4. Principle of Comparison
5. Principle of Analysis
6. Law of Probability
7. Law of Circumstantial Facts

5. 1. Law of Individuality
• Every object – natural or man made- has an
individuality
• Not duplicated in any other object
• Unique
• Neither by nature nor artificial
• eg, Currency notes, typewriters, seeds of plants,
laptops etc

6. 2. Principle of Exchange/
Locard’s Principle
When a criminal or his instrument of crime come in
contact with the victim or the objects surrounding him,
they leave traces, and the criminal or his instrument
picks up traces from the same contact
Eg., shoeprints, blood, fingerprints etc

7. 3. Law of Progressive change
“Everything changes with the passage of time”
Eg., the scene of crime undergoes rapid change

8. 4. Principle of Comparison
Only like can be compared
Emphasizes the necessity of providing like samples and
specimen for comparison with the questioned sample
Eg., if the blood found on the crime scene is A+ve,
then it cannot be compared with the person having
other blood group

9. 5. Principle of Analysis
Emphasizes the necessity of correct sampling and correct
packing for the effective use of expert
Eg., blood drops found in two sites at the same
scene may not belong to one person

10. 6. Law of Probability
All the identifications definite or indefinite are made
consciously or unconsciously on the basis of probability

11. 7. Law of Circumstantial facts
Facts do not lie, men can and do
Importance of circumstantial evidence is as good as oral
evidence
Oral evidence depends on many factors such as power of
observation, assimilation, auto suggestion

12. DISCIPLINES OF
FORENSIC SCIENCE

13. 1. Criminalists
The area of expertise to apply the techniques of the
physical and natural sciences to examine physical
evidence
Examines and identifies hair, fibers, blood, seminal and
body fluid stains, drugs, alcohol, paint, gas etc
Restores smeared or smudged markings

14. 2. Toxicology
Analyses the effect of foreign substances on human body
and behaviour
For this purpose, biological materials are subjected to a
chemical body
Exclusively focuses on the presence of chemical
substances

15. 3. Forensic Engineer
Field that applies the art and science of engineering to the purpose of
law
Assist in the prosecution or defence of criminal or regulatory matters
Typical subjects include failure analysis, accident reconstruction,
causes and origins of fires or explosions, design review, quality
evaluation of construction or manufacturing, maintenance procedures
and environment definition

16. 4. Jurisprudence
Main players of the court room
Must be knowledgeable of the law that governs the
admissibility of forensic evidence, present and challenge
forensic evidence in depositions and court proceedings

17. 5. Odontology/Forensic Dentistry
Branch that involves the application of dental science to
the identification of unknown human remains and bite
marks using both physical and biological dental evidence
Identification of human remains of natural disasters,
terrorist activities and missing and unknown persons

18. 6. Pathology
Study of disease by performing a surgery called autopsy
and examining the tissues removed and by observing
surgically removed specimens under the microscope
Analysis of fluids taken from the body such as blood or
urine also provides information about disease to the
pathologist