1
Q
The application of scientific principles to matters involving the law.
A
Forensic Science
Forensic science integrates various scientific disciplines to assist in legal investigations.
2
Q
A French criminologist known as the father of modern forensics who established the world’s first crime laboratory in Lyons, France (1910).
A
Dr. Edmund Locard
Dr. Locard’s work laid the foundation for modern forensic science.
3
Q
What is the Locard Exchange Principle?
A
Every contact leaves a trace.
This principle asserts that criminals will leave evidence at a crime scene and take evidence away with them.
4
Q
What does the Locard Exchange Principle state about criminal contact?
A
Every criminal can be connected to a crime by particles carried from the crime scene.
This principle emphasizes the importance of trace evidence in forensic investigations.
5
Q
Fill in the blank: Whenever a criminal comes into contact with a victim, an object, or a crime scene, he/she will leave behind evidence, and will also take away _______.
A
evidence
This highlights the reciprocal nature of evidence transfer during criminal acts.
6
Q
What is the origin of the term ‘forensic’?
A
It comes from the Latin word ‘forum’, meaning marketplace or public gathering.
The term reflects the historical connection between law and public discourse.
7
Q
A branch of chemistry that deals with the application of chemical principles in the solution of problems related to the law.
A
Forensic Chemistry.
Forensic chemistry includes analyzing substances found at crime scenes.
8
Q
What is the primary focus of forensic chemistry?
A
The application of chemical principles to solve legal problems.
This can involve analyzing drugs, toxic substances, and other materials relevant to legal cases.
9
Q
What kinds of specialists are included in forensic science?
A
DNA Examiner, Ballistician, Forensic photographer, etc.
These specialists apply their expertise to various aspects of forensic investigations.
10
Q
True or False: Forensic science only involves the study of physical evidence.
A
False
Forensic science encompasses a wide range of scientific disciplines, including biology, chemistry, and physics.
11
Q
What does forensic chemistry analyze?
A
Substances found at crime scenes and their chemical properties.
This analysis can provide critical evidence in criminal investigations.
12
Q
It is the branch of science that defines the nature, effects, and detection of substances present in specific matters.
A
Toxicology
13
Q
A branch of chemistry that deals with the application of chemical principles in solving problems related to the administration of justice.
A
Forensic Chemistry
14
Q
A person who practices Forensic Chemistry to aid in investigations and solve legal problems.
A
A Forensic Chemist
15
Q
It is the use of toxicology principles to aid medico-legal investigations of deaths and poisonings.
A
Forensic Toxicology
16
Q
Who is Prof. Mathieu Orfila?
A
Prof. Mathieu Orfila was a Spanish toxicologist, chemist, and medical professor in France, known as the Father of Modern Forensic Toxicology.
17
Q
What significant case did Prof. Mathieu Orfila testify in?
A
He testified as an expert witness against Madam Marie Lafarge, who poisoned her husband, Charles Lafarge, with arsenic.
18
Q
What chemical technique did Orfila use to identify arsenic?
A
Orfila used the Marsch test to identify arsenic from the body of Charles Lafarge.
19
Q
Refers to an area or vicinity of occurrence that contains evidence related to a crime.
A
Crime Scene
20
Q
Is the means sanctioned by the Revised Rules of Court to ascertain the truth regarding a matter of fact.
A
Evidence (legal definition)
21
Q
These are articles and materials found in connection with an investigation that aid in establishing the identity of the perpetrator or circumstances of the crime.
A
Physical Evidence
22
Q
These are known specimens used to compare with questioned items to establish a suspect’s relationship to the crime under investigation.
A
Standard Specimens
23
Q
What is the value of physical evidence compared to testimonial evidence?
A
Physical evidence is much more reliable than testimonial evidence. It cannot change or be lost, while testimonial evidence may be subject to human factors such as lying or forgetting.
24
Q
What are the classifications of evidence in forensic chemistry?
A
Evidence is classified into three categories: Chemical, Biological, and Physical.
25
What types of evidence fall under the Chemical classification?
Chemical evidence includes drugs and toxic substances, pigments, solvents, explosives/ballistic materials, gunshot residue, resins, fibers, oils, and alcohol.
26
What types of evidence fall under the Biological classification?
Biological evidence includes blood, body fluids, tissue, plant-derived material, saliva, urine, and feathers.
27
A written record of all individuals who maintained unbroken control over items of evidence collected from a crime scene, establishing proof of their origin.
The Chain of Custody
28
What information is included in the chain of custody?
The chain of custody includes the date and time evidence was handled, standard for comparison, maintenance of individuality, and labeling and sealing.
29
What are the four stages in the practice of forensic chemistry?
1. Collection or reception of specimen to be examined;
2. Actual examination;
3. Communication of results of examination;
4. Court appearance
30
First guiding principle in the collection of physical evidence: sufficient weight, volume, or pieces of sample for analysis should be submitted.
Sufficiency of sample
31
Second guiding principle in the collection of physical evidence: a standard should be submitted for comparative analysis.
Standard for comparison
32
Third guiding principle in the collection of physical evidence: different specimens should be packed individually to prevent contamination.
Maintenance of individuality
33
Fourth guiding principle in the collection of physical evidence: individually packed specimens should be labeled and sealed properly.
Labeling and sealing
34
What is the scope of forensic chemistry?
It includes the chemical side of criminal investigation and analysis of materials that may lead to legal proceedings.
35
The first golden rule in the practice of chemistry: Take all time to make the test complete, regardless of urgency.
GO SLOWLY
36
The second golden rule in the practice of chemistry: Make careful observations and conduct all sufficient tests to prevent mistakes.
BE THOROUGH
37
The third golden rule in the practice of chemistry: Use laboratory notebooks, photographs, or voice recorders to record observations.
TAKE NOTES
38
The fourth golden rule in the practice of chemistry: Consulting others who handled similar cases can improve performance.
CONSULT OTHERS
39
The fifth golden rule in the practice of chemistry states: Be imaginative and think ahead about the outcome of the analysis.
USE IMAGINATION
40
The sixth golden rule in the practice of chemistry which states: Explain in layman's terms for better understanding.
AVOID COMPLICATED THEORIES
41
What contributes to the destruction of evidence/specimen?
- Failure to consider the golden rules,
- Improper packing of specimen,
- Failure of identification of specimen,
- Lack of precautions to prevent tampering, and
- Improper use in transmitting the specimen.
42
What is the role of the forensic chemist in criminal investigations?
The forensic chemist aids investigations by determining if a location is a clandestine laboratory, examining marked bills during entrapment, and taking paraffin tests.
43
What law governs the practice of forensic chemistry in the Philippines?
The practice is covered by Republic Act No 754, also known as the Chemistry Law, enacted on June 18, 1952.
44
What are the characteristics of a forensic chemist?
A forensic chemist must possess moral integrity, be able to rigorously apply analytical techniques to evidence, and clearly answer challenges to findings.
45
What are the functions of a forensic chemist?
Functions include conducting examinations of dangerous drugs, explosives, firearms, gunpowder residues, toxicological examinations, fake products, blood alcohol, and urine for drugs, as well as research, training, and court testimony.
46
What is the Comprehensive Dangerous Drugs Act of 2002?
It is R.A. 9165, which includes the examination of dangerous drugs and volatile substances.
47
What does Presidential Decree 1866 cover?
It covers the examination of explosives and explosive ingredients.
48
What is the purpose of conducting gunpowder examination?
To verify possible gunshot distance.
49
What types of substances are examined in **chemico-toxicological examinations**?
Human internal organs, gastric contents, blood, water, food samples, and other substances.
50
What is the role of a forensic chemist in unfair trade competition?
To conduct examinations of *fake products* such as bleach, cement, and liquor brands.
51
What does blood alcohol determination involve?
It involves testing blood for the presence of alcohol.
52
What is examined in urine and other bodily fluids?
The presence of dangerous drugs.
53
What additional roles does a forensic chemist have?
- Conducting research
- Delivering lectures
- Testifying in court, and
- Responding to queries from investigative units
54
What is involved in field laboratory work?
Conducting investigations in clandestine laboratories.
55
What is a witness?
One who personally sees or *perceives* a thing; one who testifies as to what he has seen, heard or otherwise observed.
56
What is an ordinary witness?
States facts and may not express conclusions. He may testify to impressions as opinions of common experiments such as the speed of a vehicle or whether a voice was that of a man, woman, or child.
57
One who possesses a special skill in art, trade, or science, or has special knowledge not generally known to men of ordinary education and experiments.
Expert witness
58
What qualifications must a forensic chemist have to be an expert witness in court?
1. **EDUCATION** - must be a licensed/registered chemist, preferably with a Master's or Ph.D. degree.
2. **TRAINING** - must have undergone training and seminars in forensics and be updated in forensic chemistry procedures.
3. **EXPERIENCE** - must have hands-on experience in laboratory procedures and know how to answer court inquiries about chemistry principles.
59
What is the difference between an ordinary witness and an expert witness?
An **ordinary witness** can only state what he has perceived, while an **expert witness** may also give opinions, deductions, or conclusions based on his perceptions.
60
What are the qualifications of an ordinary witness?
- He must have the organ and power to perceive
- the perception gathered can be imparted to others, and
- he does not fall under any exceptions provided for Sec. 26, Rule 123, Rules of Court.
61
Who is the ideal person to collect evidence?
The Forensic Chemist.
62
Known specimens used to compare with questioned items to aid in establishing a suspect's relationship to the crime under investigation.
Standard Specimens
63
In the collection of evidence, “partial person” to collect evidence are those who are capable of applying knowledge or theory to practice. They maybe referred to as ______________.
Person by Practice
64
What is blood referred to as in forensic chemistry?
Blood has been called the circulating tissue of the body.
65
What is blood composed of?
Blood is a highly complex mixture of cells, enzymes, proteins, and inorganic substances.
66
What is the normal pH range of blood?
The normal pH of blood is 7.35 - 7.45.
67
What happens to blood when treated with water or other reagents?
Blood becomes transparent lake color.
68
A mark or discoloration on a surface caused by blood.
A bloodstain
69
What does a lower pH indicate about blood?
The lower the pH, the blood is more acidic.
70
What does a higher pH indicate about blood?
The higher the pH, the blood is more basic.
71
What are some uses of blood in forensic investigations?
Blood can be used as circumstantial or corroborative evidence against or in favor of a perpetrator.
72
What can blood analysis determine in a forensic context?
It can determine:
- disputed parentage
- cause of death
- length of time victim survived attack
- direction of escape, origin of blood flow, and
- approximate time crime was committed
73
What are Red Blood Cells (erythrocytes)?
Red Blood Cells (RBC), or erythrocytes, are around 4-5 million per cc of blood and carry oxygen from our lungs to the rest of our bodies.
74
What is the function of White Blood Cells (leukocytes)?
White Blood Cells (WBC), or leukocytes, attack and destroy harmful microorganisms, serving as one of the body's defenses against infections.
75
What are Platelets (Thrombocytes)?
Platelets originate in bone marrow and circulate in our blood, primarily functioning to prevent and stop bleeding.
76
Is the fluid or liquid portion of blood where cells are suspended, comprising 55% of blood composition.
Plasma
77
What is the solid component of Plasma?
The solid component of plasma is 10% largely protein in nature, consisting of albumin, several globulins, and fibrinogen.
## Footnote
90% WATER
78
These are the most plentiful blood proteins, keeping fluid in the blood from leaking into tissues.
Albumins
79
These are a broad category of blood proteins that help transport fats throughout the body and assist in fighting infections.
Globulins
80
What is the role of Fibrinogens?
Fibrinogens help in the clotting of blood.
81
What are the elements of blood?
1. Plasma (55%)
2. Platelates (0.01%)
3. Red blood cells (41%)
4. White blood cells (4%)
- lymphocyte
- Basophil
- Eosinophil
- Monocyte
- Neutrophil
82
It is a straw – yellow liquid formed when clotted blood is allowed to stand for sometime and the clot contracts.
SERUM
83
Differentiate: Plasma vs. serum
Plasma is the liquid, *cell-free* part of blood, that has been treated with anti-coagulants. *Anticoagulated*
Serum is the *liquid part of blood* after coagulation, therefore devoid of clotting factors as fibrinogen. *Clotted*
84
Plasma — __________ = Serum
Fibrinogen
85
What are the PROBLEMS IN THE STUDY OF BLOOD?
- Blood is difficult to be searched, the collection, preservation, packing and transportation of specimen suspected to contain blood is another.
- Blood offers little resistance to decomposition.
## Footnote
It undergoes a rapid charge in its character with the passage of time as process of clotting and drying commences almost immediately on exposure to air.
86
____________ maybe added to blood to preserve it for a week at room temperature or Indefinitely in a refrigerator.
Sodium fluoride
87
What is the ideal preserving temperature for blood and other perishable specimens?
Between 40-50 degrees centigrade
88
Collection of blood stains should be done ____________, mere washing of garments/clotting removes the blood
as soon as possible
89
What are the two main types of blood samples collected in forensic chemistry?
Fluid blood and dried blood or blood stains.
90
How is fluid blood collected in forensic chemistry?
It is usually collected from victims or suspects using sterile syringes and stored in clean, dry, labeled containers with anticoagulants and preservatives.
91
How is dried blood or blood stains collected?
By scraping, cutting, or swabbing the stained area using sterile tools, then air-dried and stored in paper envelopes or bags.
92
What materials can contain dried blood or blood stains?
Floors, walls, weapons, clothing, and bed linens.
93
What tools are used for collecting blood samples?
Clean tissue, disposable pipette, or dropper.
94
What should be avoided when collecting blood samples?
Avoid contamination and mixing of samples.
95
How should blood samples be labeled?
With details such as case number, date, time, and collector’s name.
96
How should blood samples be stored after collection?
In a cool, dry place or refrigerated if necessary.
97
How is dried blood collected from non-absorbent surfaces?
By scraping the stain with a clean blade or scalpel onto paper, then sealing and labeling it.
98
How is dried blood collected from absorbent surfaces?
By cutting out the stained portion of the material and packaging it separately.
99
What should be done if the bloodstain is on a large object?
Submit the entire object to the laboratory if possible.
100
How should wet blood on clothing be handled?
Do not fold the clothing; air-dry it completely before packaging.
101
What type of packaging should be used for dried clothing with blood?
Use paper bags or envelopes, not plastic, to prevent mold growth.
102
Why should wet blood samples not be sealed in plastic?
Moisture can cause bacterial growth and destroy the sample.
103
What is the main precaution when collecting blood evidence?
Prevent contamination and ensure proper labeling and storage.
104
If the amount of blood is minimal, collection may best be made by placing the sample in a _____________.
normal Saline Solution
- 1 tablespoon salt in 1 quart of distilled water
105
What is the purpose of a Preliminary Test in blood examination?
To determine whether the stain contains blood or another substance and to demonstrate the presence of blood.
106
What does a Preliminary Test detect in forensic chemistry?
Whether visible stains do or do not contain blood.
107
What is the purpose of a Confirmatory Test in blood examination?
To determine whether bloodstain really contains blood and to positively identify blood.
108
What does a Confirmatory Test confirm?
The actual presence of blood in a sample.
109
What is the purpose of a Precipitin Test in blood examination?
To determine whether blood is of human or non-human origin.
110
What are the main types of tests used in blood examination?
1. Preliminary Test
2. Confirmatory Test
3. Precipitin Test
4. Blood Grouping Test.
111
What additional information can a Precipitin Test provide if the blood is non-human?
It can identify the specific animal family from which the blood originated.
112
What is the purpose of a Blood Grouping Test?
To determine the blood group of human blood.
113
What is another name for the Preliminary Test for blood?
Color Test or Chemical Examination.
114
What are the different types of Preliminary (Color) Tests for blood?
1. Benzidine Test
2. Phenolphthalein Test
3. Guaiacum Test
4. Leucomalachite Green Test
5. Luminol Test
115
What is another name for the Phenolphthalein Test?
Kastle-Meyer Test.
116
What are other names for the Guaiacum Test?
- Van Deen Test
- Day’s Test
- Schonbein’s Test
117
Who developed the Benzidine Test (Adler’s Test)?
Oskar and Rudolf Adler in 1904.
118
What is the Benzidine Test used for?
To detect minute traces of blood through an oxidation reaction that produces a intense blue color.
119
What is the reagent used in the Benzidine Test?
- Benzidine solution (small amount of powdered benzidine dissolved in glacial acetic acid)
- 3% hydrogen peroxide solution.
120
What is the procedure for the Benzidine Test?
- Place a small portion of the stained material on a white tile
- Add a drop of benzidine solution
- Then a drop of hydrogen peroxide solution.
121
What is the positive result for the Benzidine Test?
Intense blue color produced.
122
What is the limitation of the Benzidine Test?
It is not specific for blood; some oxidizing agents can also produce a blue color.
123
What is the sensitivity of the Benzidine Test?
It can detect blood up to 1:300,000 dilution.
124
What are the reagents used in the Phenolphthalein Test?
- Phenolphthalein solution ( 1–2 grams phenolphthalein to 100ml of a 25% KOH in water added with 1gram zinc powder heated until colorless)
- 3% hydrogen peroxide solution.
125
What is the procedure for the Phenolphthalein Test?
- Place a small portion of the stain on a white tile
- Add a drop of phenolphthalein solution
- Then a drop of hydrogen peroxide solution.
126
What is the positive result for the Phenolphthalein Test?
Rose color develops or deep pink color.
127
What is the limitation of the Phenolphthalein Test?
False positives may occur due to copper salts, potatoes, and horseradish.
128
What is the sensitivity of the Phenolphthalein Test (Kastle-Meyer Test) ?
It can detect blood in a dilution of 1:80,000,000 parts.
##Footnotes
- A positive results with this test is highly indicative of blood.
- The negative result is, conclusive as to the absence of blood.
129
What is the Guaiacum Test used for?
To delicate test for the presence of fresh blood in a stain. It may not react to very old stains.
## Footnotes
A solution of 1:50,000 dilution
130
What is the reagent used in the Guaiacum Test?
- Fresh tincture of gualac resin (Few lumps of this to 95% alcohol, then filter)
- 3% of hydrogen peroxide or few drops of turpentine.
131
What is the procedure for the Guaiacum Test?
- Place a small portion of the stain on a white tile
- Add a drop of tincture of guaiacum,
- Then a drop of hydrogen peroxide.
132
What is the positive result for the Guaiacum Test?
Beautiful blue color that appears immediately
133
What is the limitation of the Guaiacum Test?
The test also reacts with salvia, pus, bile, milk, rust, iron salts, cheese, gluten, potatoes, perspiration and other oxidizing substances.
134
What is the Leucomalachite Green Test used for?
To test for the presence of blood through oxidation of leucomalachite green to malachite green.
## Footnotes
This is a test not as sensitive as the benzidine test
135
What are the reagents used in the Leucomalachite Green Test?
- Leucomalachite Green solution (1gram leucomalachite green dissolved in 48 ml. glacial acetic acid and diluted to 250ml. water)
- 3% hydrogen peroxide.
136
What is the procedure for the Leucomalachite Green Test?
- A small piece of the stained fabric on a filter paper.
- Add a drop of *leucomalachite green solution*
- After a few seconds add drop of 3% *hydrogen peroxide*.
137
What is the positive result for the Leucomalachite Green Test?
Malachite green with bluish green or peacock-blue color
138
What is the Luminous (Luminol) Test used for?
To detect traces of blood that are not visible to the naked eye.
139
What is the procedure for the Luminous Test?
- By spraying luminol reagent onto a suspect item, large areas can be quickly screened for the presence of bloodstains.
- The sprayed object must be located in a *darkened area* while being viewed for the *emission of light*. (LUMINESCENCE).
140
What is the positive result for the Luminous Test?
Blue luminescence or glow in the dark
## Fotenotes
The reaction of luminol with blood results in the production of light rather than color
141
Luminol test is extremely sensitive test. It is capable of detecting bloodstains diluted up to ______________.
diluted up to 10,000X
142
It is known to destroy many important blood factors necessary for the forensic characterization of blood, so its use should be limited only to seeking out blood Invisible to the naked eye.
Luminol
143
What is the purpose of the Confirmatory Test for blood?
The actual proof that stain is blood consists of establishing the presence of the characteristic of the red blood cells of the blood.
144
What are the types of Confirmatory Tests for blood?
1. Microscopic Test
2. Microchemical Test (Microcrystalline Test)
3. Spectroscope Test
145
What is the Microscopic Test used for?
Useful for the demonstration of blood corpuscles for making the distinction between *mammallan, avian, piscine, and reptilian blood* and for the investigation of menstrual, lochial and nasal charges.
## Footnote
In short it differentiates mammalian, avian, piscine and reptilian blood.
146
Distinction of Red blood cells:
- Mammalian
- Birds, Fish and Reptiles
- Amphibians
*Mammalian*- red blood cells are circular, biconcave disc without nucleus.
*Birds, Fish and Reptiles*- red blood cells langer, oval and nucleated.
*Amphibians*- red blood cells are larger than mammals, oval and nucleated
147
What is another name for the Microchemical Test?
Microcrystalline Test
148
What is the purpose of the Microchemical (Microcrystalline) Test?
To confirm the presence of blood by forming characteristic crystals from hemoglobin derivatives.
149
What are the three main types of Microchemical Tests?
1. Hemochromogen Crystal Test (Takayama Test)
2. Hemin Crystal Test (Teichmann Test)
3. Acetone-Haemin of Wagenhaar test
150
What is the procedure of Hemochromogen Crystal Test / Takayama Test?
- Fragment of the suspected material is placed on a slide glass
- A drop of *hemochromogen reagent* is added
- A cover glass is placed on top and heated gradually for a time
- Then examined under the microscope.
151
Positive Result of Hemochromogen Crystal Test / Takayama Test.
Crystals varying from salmon color to dark brown and pink and which are Irregular rhomboids or in clusters, may be seen.
152
Procedure on TEICHMANN'S BLOOD CRYSTALS OR HEMIN CRYSTALS TEST
- On the microscopic slide is placed fragments of the stain
- A drop of water with trace of *sodium chloride* added
- Add *glacial acetic acid*
- Evaporate to dryness under a cover slip.
153
Positive Result of TEICHMANN'S BLOOD CRYSTALS OR HEMIN CRYSTALS TEST.
Dark Drown rhombic prisms of chioride of hematin are formed.
154
This Is considered as the best of the micro-chemical test.
TEICHMANN'S BLOOD CRYSTALS OR HEMIN CRYSTALS TEST
155
What is the Produre for ACETONE-HAEMIN OF WAGENHAAR TEST?
- A particle of dried stain or a fiber of the stained fabric is placed on a glass slide and covered with a cover slip with a *needle* interposed to prevent direct contact of the cover slip with the slide.
- A drop of *acetone* is run under the cover slip so that the material is surrounded and
- A drop of *diluted oxalic or acetic acid* is then added
156
This examination depends on the principle that *blood pigments* have the power to *absorb light* of certain wave length and produce certain characteristic absorption bands on the spectrum
SPECTROSCOPIC EXAMINATION
157
This is the almost delicate and reliable test for the determination of the presence of blood in both old recent stains.
Spectroscope Test
158
What optical instrument is used to perform Spectroscope Test?
SPECTROSCOPE
159
What are the three types of Physical Examinations of Blood?
1. Solubility Test
2. Heat Test
3. Microscopic Test
160
Recent blood shed is soluble in saline solution and imparts a bright red color. Stains which have been exposed to air become dry; hemoglobin is transformed to meth-hemoglobin or hematin. If the stain has been kept in damp places for a long time; hemoglobin is transformed to hematin.
SOLUBILITY TEST
161
In solubility test:
- Recent blood shed + _____________ = bright red color
saline solution
## Footnotes
Recent blood shed is soluble in *saline solution* and imparts a bright red color
162
In solubility test:
- Stains + air = __________.
Dry blood/stains
## Footnote
- Stains which have been exposed to air become dry;
- Hemoglobin is transformed to **meth-hemoglobin or hematin**.
163
In solubility test:
If the stain has been kept in damp places for a long time; hemoglobin is transformed to ___________.
Hematin
164
A test where solution of the blood stain is heated and impart a *muddy precipitate* as a result.
HEAT TEST
165
A test wherein stains on dark fabric mixed with mud, paint, etc. emit *bluish white luminescence* in a dark room
LUMINESCENCE TEST
166
What is the Biologic Examination of Blood used for?
To determine whether the blood is of human or animal origin.
167
What is the name of the test used in Biologic Examination of Blood used to determine whether the blood is of human or animal origin?
The Precipitin Test.
168
What is the reagent used in the Precipitin Test?
Antiserum/ Precipitin
169
What is the positive result for the Precipitin Test?
- Formation of a *white cloudy line or ring or band* at the contact points of the fluid
- Appears *immediately or within 1 or 2 minutes*.
170
What is the procedure for the Precipitin Test?
1. Scrape off blood stain if on hard material.
2. Powder the scrapings and exact with saline solution.
3. If the stain is cloth, paper or similar material, cut a small portion and then place in a *test tube* and add extract with saline solution. *NOTE*: Allow mixture to stand overnight.
4. Centrifuge to clean the solution.
5. Dilute with saline solution.
6. Layer an extract of the bloodstain on top of the human antiserum/precipitin in a *capillary tube*.
171
What is the limitation of the Precipitin Test?
The precipitin reacts not only with blood proteins but also with other body proteins as those as saliva, semen, mucus and other *body fluids*.
172
What are the four main human blood groups?
1. Group O
2. Group A
3. Group B
4. Group AB
173
These are characteristic chemical structures or "principles" that the found on the surface of each red blood cells which stimulates the production of agglutinins or antibodies.
AGGLUTINOGEN OR ANTIGEN
174
What are the two different classificatiom of agglutinogens or antigens?
1. AGGLUTINOGEN A OR ANTIGEN A
2. AGGLUTINOGEN B OR ANTIGEN B.
175
These are properties or "principles" contained in the serum which cause agglutination or clumping together of the red blood cells.
ANTIBODY OR AGGLUTININ
## Footnote
They are antitoxic substances within the body which reacts when confronted with a specific antigen to protect the system.
176
What are two different classifications of agglutinins?
1. Anti-A
2. Anti-B
## Footnotes
Agglutinins are demonstrable in about 50% of newly born infants.
177
This test determines blood type and compatibility
Blood Type Test
178
Which blood group is the universal donor?
Blood Group O
179
Which blood group is the universal recipient?
Blood Group AB
180
Which blood group can donate to all other blood groups?
Blood Group O
181
Which blood group can receive from all other groups?
Blood Group AB
182
Which blood group can receive only from the same group?
Blood Group O
183
Which blood group can donate only to the same group?
Blood Group AB
184
185
What is the function of the microscope in forensic blood analysis?
To observe the shape and structure of blood cells.
186
What are the main parts of a microscope?
1. Eyepiece lenses
2. Objective lenses
3. Stage with clips
4. Illuminator
5. Adjustment knobs
6. Tube, arm and base
7. Fine and coarse focus
8. Rackstop
9. Revolving nosepiese/ Turret
187
What can blood types provide in forensic chemistry?
Class evidence
188
What can DNA profiling from blood provide?
Individual evidence
189
What can blood spatter/ evidence provide information about?
1. Truthfulness of an account of witness/ suspect
2. Origin of the blood
3. Angle and velocity of impact
4. Type of weapon used
190
What can the analysis of blood spatter pattern determine?
- direction blood traveled
- angle of impact
- point of origin of the blood
- velocity of the blood
- manner of death
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What are the six main blood spatter patterns?
1. Passive drops
2. Arterial gushes
3. Splashes
4. Smears
5. Trails
6. Pools
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What does a circular or spherical blood drop indicate about the angle of impact?
It fell at a **90-degree** angle.
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What happens to a blood drop when it falls from a greater height?
It produces a larger diameter and may create *satellite spatter*.
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Small droplets of blood that break off from the main drop upon impact.
Satellite spatter
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What is the effect of surface texture on blood spatter?
- Smooth surfaces produce round drops, while
- Rough surfaces cause irregular edges (spiking patterns around the drop) and satellite spatter.
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How Bloodstain Pattern Analysis Works?
The higher the drop, the higher the velocity and the larger the diameter
## Footnote
The higher the fall, the larger the diameter of the drop until it reaches a limit.
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These are formed when blood falls directly onto a floor at a 90-degree angle. This produces circular drops, that may have more spikes or satellites depending on the type of surface it is landing on
PASSIVE DROPS
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Blood spatter patterns that are caused by blood spraying out of the wound due to the pumping action of the heart. These will only occur when a major artery has been cut (veins do not squirt)
ARTERIAL GUSHES
## Footnotes
These are typically found on walls and ceilings
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The shape and position of the spatter pattern can help locate the position of the victim at the time of the attack
SPLASHES
##Footnotes
- Splashes are usually shaped like exclamation points.
- The force of impact when blood hits a surface at an angle or speed.
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These are left when a victim is bleeding and deposits blood as he or she touches or brushes againts a wall or piece of furniture
SMEARS
##Footnotes
Patterns created when a bloody object or person comes into contact with another surface.
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These blood spatter patterns can be left if a bleeding victim is moving from one location to another or is being moved
TRAILS
##Footnotes
Trails can also be left If something is dragged through the blood
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These form around a victim who is bleeding heavily and remains in one place
POOLS
##Footnotes
If the victim moves or is moved there may appear to be droplets or smearin connecting the two location
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How can the shape of blood drops help identify the weapon?
The size and distribution of drops correspond to the force and type of weapon used.
##Footnotes
Blood from a *gunshot* wound sprays out in a fine mist, while a wound caused by being struck with a *pipe* will cause larger drops
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What are the three main categories of blood spatter velocity?
1. Low velocity
2. Medium velocity
3. High velocity
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What are the characteristics of a low velosity spatter?
- Consist of large separate or compounded drops with diameters of **3 mm or more**.
- Produced by minimal force and hits the surface with **less than 5 feet per second velocity** dripping blood from a wound
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What are the characteristics of a medium velocity spatter?
- Consists of small drops with diameters of **1- 3mm**.
- Travel at an average of **5 to 25 feet per second**
##Footnotes
They are commonly associated with blunt force trauma
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What are the characteristics of a high velocity spatter?
- Drops with diameter of less than **1 mm**.
- Hits at **more than 100 feet per second** Gunshot spray
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A pattern created when a blood-covered object fling blood in an arc onto a nearby surface.
CAST OFF PATTERNS
##Footnotes
A pattern created when blood is flung from a blood-covered object onto a nearby surface.
FORENSIC SCIENCE
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