Forensic chemistry and toxicology are discussed. Key points include defining forensic science as the application of scientific techniques to solve crimes, providing knowledge of physical evidence. The history of the fields is reviewed, noting figures like Orfila and Marsh who advanced techniques like toxicology. Crime laboratories are introduced as the place where physical and chemical analysis is conducted to study evidence like drugs, fingerprints, firearms. The roles of forensic chemists are outlined in collecting, examining, and communicating results of samples to help solve legal cases.

1. FORENSIC
CHEMISTRY
AND
TOXICOLOGY
By: LOTHES J. SAMANTE

2. GOALS and OBJECTIVES:
 Define and discuss the meaning of criminalistics or forensic
science.
 To have knowledge on Physical Evidence.
 To know the Importance of Forensic Science.

3. CRIMINALISTICS or FORENSIC SCIENCE
 Defined as the study of criminal things.

4.  It involves the application of scientific techniques to
the solution of crime.

5. It provides a basic
knowledge of physical
evidence.

6. Physical Evidence
 is any object that can
establish that a crime has
been committed or can
provide a link between a
crime and its victim or
between a crime and its
perpetrator.

7. Examples of Physical Evidence
photography, fingerprints and other impression, ballistics, glass,
hair, fiber, paint, handwriting and document examination, drugs
and instrumental method of analysis.

8.  It also provides technique of comparing an item discovered at
the scene of the crime with an item associated with or found on
the suspect.

9.  It is also defined as the forging of many scientific disciplines
into one relevant, concerted effort, under the rules of evidence,
to establish circumstantially the innocence or guilt of the
accused.

10. IMPORTANCE OF FORENSIC
SCIENCE
Forensic science is the marriage of natural science principles and
the law. In this union, forensic professionals use their scientific
backgrounds to help law enforcement personnel solve crimes.

11. FORENSIC CHEMISTRY
 Is the branch of chemistry which deals with the application of
chemical principles in the solution of problems arising from the
administration of justice.
 It is chemistry applied in the elucidation of legal problems.
 It is chemistry used in courts of law.
 It is chemistry that belongs to the courts of law.

12. THE HISTORY OF FORENSIC CHEMISTRY
AND TOXICOLOGY
“Forensic Chemistry is the application of chemical science or
chemistry in solving or proving the crime in the court of law.
Chemical science is being used for the analysis of pieces of
evidence found at the scene of a crime.”
The history of forensic chemistry is holding the facts of
methods developed by a scientist for the identification and
analysis of poisons, which were used for the commission of
murders. The pieces of evidence of the use of poisons come from
the early Egyptians, Romans, and Greeks.

13. THE HISTORY OF FORENSIC CHEMISTRY
AND TOXICOLOGY
(1813) Mathieu Orfila
- is considered the father of modern
toxicology. He also made significant
contributions to the development of tests for
the presence of blood in a forensic context and
is credited as the first to attempt the use of a
microscope in the assessment of blood and
semen stains. a Spaniard who became professor of
medicinal/forensic chemistry at
University of Paris, published Traite des
Poisons Tires des Regnes Mineral,
Vegetal et Animal, ou Toxicologie
(General Toxicology).

14. THE HISTORY OF FORENSIC CHEMISTRY
AND TOXICOLOGY
 Democritus - was probably the first chemist to study poisons, and he communicated
some of his findings to Hippocrates .
 (1836) James Marsh - an Scottish chemist, was the first to use toxicology (arsenic
detection) in a jury trial.
 (1851) Jean Servais Stas - a chemistry professor from Brussels, Belgium, was the first
to successfully identify vegetable poisons in body tissue.
 (1910) Edmund Locard - professor of forensic medicine at the University of Lyons,
France, established the first police crime laboratory.
 (1960) Lucas - in Canada, described the application of gas chromatography to the
identification of petroleum products in the forensic laboratory and discussed potential
limitations in the brand identity of gasoline.
 (1976) Zoro and Hadley - in the United Kingdom first evaluated chromatograph-mass
spectrometry for forensic purposes.

15. THE HISTORY OF FORENSIC CHEMISTRY
AND TOXICOLOGY
 1918-(New York City)appointed the first trained medical
 Charles Norris was the first appointed chief medical examiner and
Alexander Gettler (chemist and partner of Norris) rewrote the rules of
crime detection in America.

16. THE ANCIENT ISSUES IN FORENSIC
CHEMISTRY AND TOXICOLOGY
 Poisons were employed by early Egyptians and ancient Greeks and Romans.
 Poisons were used both for murder and as a means of execution; the
philosopher Socrates was condemned to death by drinking hemlock .
 In Ancient Roman civilization had laws against poisoning in 82 B.C.E. Before the development
of systematic, scientific criminal investigation, guilt was determined largely by circumstantial
evidence and hearsay.
 Arsenic was a popular poison in Roman times. It was referred to as inheritance powder in
early France.
 The Blandy trial of 1752 was the first instance of an actual chemical test for poison.
 the Marsh test, developed in 1836, was the first reliable analysis that could show
scientifically that arsenic was present in the body of a victim.

17. IMPORTANCE OF FORENSIC CHEMISTRY
AND TOXICOLOGY
 Forensic science can solve mysteries surrounding deaths, whether the
cause is natural or foul play.
 It involves the examination of the specimens found in the crime scene like
blood, hair, and other types of fluid found that has connection to the
perpetrator.
 It can allow the authorities to do positively identify the suspect in a crime
to determine exactly when and how a crime occurred.
IN OTHER WORDS;
The goal of forensic chemistry is to determine the
provenance of a sample and link it to a person or thing.

18. What is a crime laboratory?
 It is where the physical and chemical examination conducted.

19. Edmond Locard
 Considered as the father of the crime laboratory.

20. Walker Mc Crone
 Considered as the father of microscopic
forensics.

21. Different Units in the Crime Laboratory:
1. Physical Science Unit – identification and comparison of
drugs, glass, paint, explosives and soil using chemical tests
and modern analytical instruments.
2. Biology Unit – identification and grouping of dried bloodstains
and other body fluids, comparison of hairs and fibers and the
identification and comparison of botanical materials such as
woods and plants.

22. 3. Firearms Unit – examination of firearms, discharged bullets,
cartridge cases, shotgun shells and all types of ammunition. Garments
and other objects are also examined in this unit to determine the
presence of discharge residues and to approximate target distance.
4. Document Examination Unit- examination of handwriting and
typewriting on questioned documents to ascertain authenticity and/or
source. It includes also the analysis of paper and ink and examination
of indented writings, obliterations, erasures and burned or charred
documents.

23. 5. Photography Unit – aids in the preparation photographic
exhibits for courtroom presentation using highly specialized
photographic technique of infrared, ultraviolet and x-rays.
6. Toxicology Unit – examination of body fluids and organs for the
presence or absence of drugs and poisons.

24. 7. Latent Fingerprint Unit – processing and examination of
evidence for invisible or latent fingerprints.
8. Polygraph Unit – applies the techniques of criminal
investigation and interrogation.

25. 9. Voiceprint Analysis Unit – where telephoned threats and tape-
recorded messages are examined using an instrument, the
sound spectrograph, that transforms speech into a visual graphic
display called voiceprint.
10. Evidence Collection Unit – dispatches specially trained
personnel ( civilian/ police) to the crime scene to collect and
preserve physical evidence.

26. WHO ARE EXPERT WITNESS?
 Expert witness are person who testifies his personal
knowledge on certain issues in court provided he is not
disqualified by law.

27. Qualifications of an Expert Witness:
 He must be competent (cite educational degrees, participation
in special courses, published books and articles, membership
in professional societies).
 He must be experienced ( state number of years on
occupational experience).

28. FORENSIC CHEMIST
Is one who practices Forensic Chemistry.

29. Scope of Forensic Chemistry:
1. It includes the chemical side of criminal investigation.
2. It includes the analysis of any material the quality of which
may give rise to legal proceedings.
3. It is not limited to purely chemical questions involved in legal
proceedings.
4. It has invaded other branches of forensic sciences notably
legal medicine, ballistics, questioned documents,
dactyloscopy and photography.

30. Role of Forensic Chemist in the Scientific
Criminal Investigation:
 Determining whether or not a place or location is a clandestine
laboratory ( a secret location utilized for the purpose of producing
illicit drugs or illicitly producing licit drugs.
 Examining suspect’s hand and marked bills for the presence of
fluorescent powder and invisible markings during extortion cases.
 Taking of paraffin cast.

31. Practice of Forensic Chemistry
The work of forensic chemist is divided into four stages, namely:
1. Collection or reception of the specimen.
2. The actual examination.
3. The communication of the results of the examination.
4. Court appearance.

32. Collection of the specimen to be examined
The proper collection, preservation and transportation of
specimens are essential in the investigation of crime. Hence,
whenever possible, the chemist should personally collect all the
specimens necessary for the examination. This particular stage
of a forensic chemist’s work is essential as questions regarding
the collection, preservation and transportation of the specimen
are raised during trial.

33. Factors That Must Considered When
Collecting Specimen For Examinations:
1. Sufficiency of Samples
2. Standard for Comparison
3. Maintenance of Individuality
4. Labelling and Sealing

34. Sufficiency of Samples
 As much as possible, the investigator should collect sufficient
amount of specimen for examination. This will make the
chemist confident that in case of doubtful result, he or she can
still have enough samples to repeat or to proceed to the
succeeding examinations.

35. Standard for Comparison
 When the evidence in question is located in or added with
foreign substance, a sample of such foreign substance must
be submitted for analysis. For instance, if blood is found on
linoleum, a sample of the unstained linoleum must be
submitted together with the stained portion. In cases of
adulteration or unfair trade competition, a genuine sample
must be submitted for comparison. In the examination of hair,
textile fiber, soil, etc., standard samples must be submitted for
comparison.

36. GOLDEN RULES IN THE PRACTICE OF
FORENSIC CHEMISTRY
The six golden rules in the practice of forensic chemistry
are;
1. Go slow
2. Be thorough
3. Take notes
4. Consult others
5. Use Imagination
6. Avoid complicated theory

37. GOLDEN RULES IN THE PRACTICE OF
FORENSIC CHEMISTRY
1. Go slowly: good work cannot be hurried, therefore take all the time
necessary to make the case complete, no matter how urgent it may
appear or how pressing others may be for the result; it is generally
possible to adjourn a case if work cannot be finish in time.
2. Be thorough; make a careful and minute examination of everything and
do not be satisfied with a qualitative analysis if a quantitative one be
possible; it always pays to do too much rather than too little and it is
difficult to foresee what will or will not be required in court.
3. Take notes; keep a full, neat and clear record of everything seen and
done.

38. GOLDEN RULES IN THE PRACTICE OF
FORENSIC CHEMISTRY
4. Consult others; many cases will lead the expert into paths with which he is not
familiar, and when this happen he should consult those who are most likely to
know.
5. Use imagination; this is somewhat hazardous advice, since an expert with a vivid
and uncontrolled imagination is a most dangerous person; a discipline imagination,
how ever, which enables inferences and deductions to be made from slender and
incomplete premises is often very useful. In writing the report the imagination must
be kept well in hand and the expert should remember that what to him may be
merely a helpful working hypothesis is liable to be taken by others for more than its
true worth and to be adopted by them as a final explanation.
6. Avoid complicated theories; the simplest explanation is the most likely to be the
right one.

39. END
THANK YOU…..
NOTE: GET READY FOR A SHORT QUIZ, AND HAVE A NICE DAY
EVERYONE….

40. References:
 https://forensicchemistrykrystalbryant.weebly.com/history.html
 https://sciencemonk.com/forensic-chemistry-applications-of-forensic-
chemistry/
 https://seak.com/blog/expert-witness/expert-witness-requirements/
 https://pressbooks.bccampus.ca/criminalinvestigation/chapter/chapter-3-
what-you-need-to-know-about-evidence/
 https://seak.com/blog/expert-witness/expert-witness-requirements/