Week 5

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Questions and Answers

What is the purpose of using the precipitin test in blood analysis?

To quantify the amount of blood present at a scene

To identify the presence of human or animal blood (correct)

To match DNA from the blood to a suspect

To determine the blood type of a sample

What can be inferred if there is no interaction during the precipitin test?

The sample is definitely human

The sample is contaminated

The sample is from an animal (correct)

The test results are inconclusive

Why is understanding animal blood important in crime scene investigations?

To eliminate the presence of any blood at the scene

To identify the specific animal species that may have contributed to the blood (correct)

To find matches to human suspect DNA

To determine the quantity of blood present from the suspect

What does the Kastle-Meyer test primarily determine?

The presence of hemoglobin in the sample Signup and view all the answers

How can blood spatter patterns assist in a criminal investigation?

They can reconstruct the events leading up to a violent crime Signup and view all the answers

What does the convergence point of blood droplets indicate?

The location of the blood source Signup and view all the answers

If blood droplets emanate from a single event, what can be inferred about their trajectory?

They create a backward trajectory towards the source Signup and view all the answers

Which test uses reduced Phenolphthalein as a reagent?

Kastle-Meyer Colour Test Signup and view all the answers

What can investigators determine from analyzing blood spatter patterns?

The height of the blood source above the ground Signup and view all the answers

How can investigators establish the distance between two walls in a blood spatter analysis?

By determining the angle of impact of the droplets Signup and view all the answers

What is the primary basis of the Luminol Test?

The peroxidase properties of blood Signup and view all the answers

Which of the following can lead to a false positive in the Kastle-Meyer Test?

Vegetable matter Signup and view all the answers

In blood spatter analysis, what is the significance of blood droplets converging at a point?

It helps in pinpointing the event's origin location Signup and view all the answers

What occurs when blood catalyzes the oxidation in the Kastle-Meyer Test?

Development of a pink color Signup and view all the answers

In the Precipitin Test, what is the role of injecting human blood into a rabbit?

To produce antibodies to human blood Signup and view all the answers

What is the sensitivity of the Luminol Test in detecting blood?

30 parts per million Signup and view all the answers

Which test is no longer used due to toxicity issues?

Benzidine Colour Test Signup and view all the answers

What compound does blood catalyze the breakdown of in the Luminol Test?

H2O2 Signup and view all the answers

What happens during the Luminol Test after blood catalyzes the reaction?

Blue light is emitted Signup and view all the answers

Which option correctly describes the chemical reaction in the Kastle-Meyer Test?

Blood oxidizes H2O2 to H2O Signup and view all the answers

Which component of blood is primarily responsible for oxygen transport?

Erythrocytes Signup and view all the answers

What type of blood would contain both A and B antigens on the cell surface?

Type AB Signup and view all the answers

In the ABO blood type system, which blood type has no A or B antigens present?

Type O Signup and view all the answers

What is the role of antibodies in blood serum?

To bind to foreign antigens Signup and view all the answers

Which of the following represents the most common blood type in Singapore?

Type O Signup and view all the answers

Which type of blood cells are primarily involved in the immune response?

Lymphocytes Signup and view all the answers

How many different antigens are commonly recognized in blood typing?

30 Signup and view all the answers

What percentage of blood plasma is made up of antibodies?

20% Signup and view all the answers

What property allows conducting blood spatter analysis for event reconstruction?

Pattern of blood spatter Signup and view all the answers

What mechanism primarily aids in the removal of carbon dioxide from the blood?

Conversion to bicarbonate Signup and view all the answers

What is the primary cause of arterial blood spatter?

Severed arteries Signup and view all the answers

Which type of blood spatter is likely to occur at high speeds?

High velocity spatter Signup and view all the answers

What can cause multiple spatter patterns to appear close together?

Multiple heartbeats Signup and view all the answers

What is an example of a medium velocity spatter source?

Baseball bat Signup and view all the answers

What effect does the pressure surge from the heart have on blood spatter patterns?

It influences the velocity of the blood Signup and view all the answers

What may happen during the transfer of blood from a hand to a wall?

Blood forms a splash pattern Signup and view all the answers

Which condition is indicative of low velocity blood spatter?

Free fall from 1.5 m/s Signup and view all the answers

What component contributes to the pattern created when blood dribbles down a surface?

The speed of the blood Signup and view all the answers

What did Lady Lucan shout when she ran into the pub?

Help me, help me, help me, I have just escaped from being murdered Signup and view all the answers

What was found at the crime scene that indicated a struggle had taken place?

A bloodstained lead pipe Signup and view all the answers

What was Lady Lucan's blood type as indicated in the evidence?

A Signup and view all the answers

How did Lord Lucan claim to have witnessed the incident involving Lady Lucan?

By walking past the house and observing a struggle Signup and view all the answers

What conclusion can be drawn about Lord Lucan's whereabouts after the incident?

He was legally presumed dead. Signup and view all the answers

What did blood spatter analysis indicate about the blood at the crime scene?

The blood types belonged to both Lady Lucan and the nanny. Signup and view all the answers

How did the nanny's presence at the crime scene alter the police investigation?

It helped confirm the timeline leading to the attack. Signup and view all the answers

What was the reason given for the nanny's visit to the basement?

To make tea Signup and view all the answers

Which principle states that no two fingers have the same prints, including identical twins?

First Principle Signup and view all the answers

What happens to fingerprints throughout a person's lifetime?

They do not change Signup and view all the answers

What can be stated about identical twins' fingerprints?

Their fingerprints are unique like any other person's Signup and view all the answers

What occurs if a person loses their fingerprints?

They regrow as the originals Signup and view all the answers

Why are fingerprints considered more reliable than DNA for individual identification?

No two fingerprints are ever the same Signup and view all the answers

Which statement is correct about the duration fingerprints last after death?

They last for several days Signup and view all the answers

What does the term 'friction ridges' refer to in the context of fingerprints?

The patterns formed by skin on fingers Signup and view all the answers

What are the implications of removing fingerprints?

They will grow back unchanged Signup and view all the answers

Who developed a classification system that is inspired by Japanese methods?

Henry Faulds Signup and view all the answers

What significant event in fingerprint history occurred in June 1892?

A bloody fingerprint helped solve a murder case Signup and view all the answers

Which of the following individuals added thumbprints to the Bertillon system?

Edward Henry Signup and view all the answers

What material did Henry Faulds find that demonstrated the potential of fingerprints for identification?

Glass and clay Signup and view all the answers

What was the outcome of Edward Henry’s investigation into the murder of Walter and Ann Farrow?

A thumbprint matched one of the alleged criminals Signup and view all the answers

Which of these authors depicted fingerprint evidence in their literary works?

Mark Twain Signup and view all the answers

What type of fingerprint is not visible to the naked eye?

Latent fingerprints Signup and view all the answers

What did the discovery of animal fingerprints by Locard contribute to forensics?

Emphasized the possibility of identifying criminals through non-human prints Signup and view all the answers

Which chemical method reacts with amino acids during fingerprint visualization?

Ninhydrin Signup and view all the answers

In the fingerprints, what term is used to refer to the lines that help grip objects?

Friction ridges Signup and view all the answers

What effect does damaging a finger have on a fingerprint?

The fingerprint cannot grow back if damaged deeply. Signup and view all the answers

Which of the following is a method used for dusting latent fingerprints?

Molybdenum Disulfide Signup and view all the answers

What identity change did Marc George undergo after his surgery?

His fingerprint was replaced with a footprint. Signup and view all the answers

What happens during fuming with cyanoacrylate in fingerprint analysis?

Vapors polymerize on the fingerprint. Signup and view all the answers

How did the investigation in Jalpaiguri tea garden identify Kangali Charan as a suspect?

A bloody thumbprint matched his record Signup and view all the answers

Infra-red microscopy is used in fingerprint analysis primarily to determine what?

The presence of explosive residues Signup and view all the answers

Which fingerprint pattern describes a spiral design?

Whirl Signup and view all the answers

What is the significance of ridge endings in fingerprint identification?

They represent points where a ridge terminates. Signup and view all the answers

Which option is commonly used to preserve a fingerprint after it has been lifted?

Lifting it onto tape Signup and view all the answers

In what year was Dr. Jose Covarrubias sentenced, according to the given content?

2008 Signup and view all the answers

Which of the following is NOT a component of fingerprints?

Vinegar compounds Signup and view all the answers

Electronic databases for fingerprint matching typically provide what types of matches?

Inexact but close matches Signup and view all the answers

What type of fingerprint pattern is categorized as a 'spur'?

A ridge ending that extends outward. Signup and view all the answers

Iodine spray is often used in fingerprint analysis to achieve what?

To provide a color indication Signup and view all the answers

What percentage of visible prints can ideally be seen with the naked eye?

2% Signup and view all the answers

Which of the following best describes the term 'bifurcation' in fingerprints?

A point where a single ridge divides into two. Signup and view all the answers

What is the first principle regarding the classification of fingerprint patterns?

They can be classified into different categories. Signup and view all the answers

What is the consequence of deeply damaging your finger according to the content?

Your fingerprint will eventually grow back. Signup and view all the answers

Which procedure was used to alter Marc George's identity?

Skin removal from his fingertips Signup and view all the answers

Which pattern classifications are included in fingerprint analysis?

Whirl and double loop Signup and view all the answers

How visible are fingerprint impressions to the naked eye?

Typically invisible without enhancement Signup and view all the answers

What is the relationship between identical twins' fingerprints?

Their fingerprints will show some similarities but are unique. Signup and view all the answers

What occurs when the ridges of a fingerprint sustain damage?

Ridges become indecipherable. Signup and view all the answers

What is mentioned as a method to 'fake' fingerprints?

Replacing skin from another body part Signup and view all the answers

What type of fingerprint pattern is characterized by two loops?

Double loop Signup and view all the answers

What principle states that no two fingers have the same fingerprints, including identical twins?

First Principle of Fingerprints Signup and view all the answers

Which statement about fingerprints is true?

Fingerprints remain unchanged throughout a person's lifetime. Signup and view all the answers

What happens to fingerprints if they are damaged?

They regrow in the same pattern. Signup and view all the answers

What statistical claim is made about DNA?

Identical twins have the same DNA. Signup and view all the answers

Why can fingerprints be used as a reliable form of identification?

Fingerprints can be unique to individuals. Signup and view all the answers

What is one characteristic that differentiates fingerprints from DNA?

Fingerprints do not change during a lifetime. Signup and view all the answers

Which of the following correctly describes the permanence of fingerprints?

They remain for a period after death. Signup and view all the answers

How do fingerprints contribute to the concept of individuality?

They leave unique patterns that cannot be replicated. Signup and view all the answers

Who was the first to introduce the use of fingerprints on contracts?

William Herschel Signup and view all the answers

What did Henry Faulds contribute to the field of fingerprinting?

The idea that finger impressions can identify criminals Signup and view all the answers

Which of the following individuals attempted to set up a national fingerprint database in Argentina?

Juan Vucetich Signup and view all the answers

In the case of the Stratton Brothers, how was the match to Alfred Stratton determined?

A bloody fingerprint found at the crime scene Signup and view all the answers

What term describes the lines on fingerprints?

Friction ridges Signup and view all the answers

What is the primary component responsible for the visibility of latent fingerprints?

Chemical visualisation Signup and view all the answers

Which literary work references fingerprints in relation to identification?

Pudd’nhead Wilson Signup and view all the answers

Which method utilizes ninhydrin to make fingerprints visible?

Chemical visualisation Signup and view all the answers

What was the outcome of the fingerprint evidence found at the murder scene involving Francesca Rojas?

Her own confession Signup and view all the answers

Which significant contribution did Edward Henry make to fingerprint systems?

Developing a classification system that included thumbprints Signup and view all the answers

What substance is used in laser fluorescence to enhance the visualisation of fingerprints?

Dye Signup and view all the answers

What was one of the main criticisms faced by Juan Vucetich when trying to establish a fingerprint database?

Public opposition Signup and view all the answers

Which chemical is released during fuming cyanoacrylate to visualise fingerprints?

Superglue vapour Signup and view all the answers

How are fingerprints primarily visualized at a crime scene?

With dusting powders or chemicals Signup and view all the answers

Which principle describes the uniqueness of fingerprint patterns?

Third Principle Signup and view all the answers

What is a common use of electronic databases in relation to fingerprints?

To provide close matches Signup and view all the answers

Which of the following visualisation methods reacts with fats and proteins in fingerprints?

Ninhydrin Signup and view all the answers

What role does the background contrast play in fingerprint dusting?

It influences the visibility of the print Signup and view all the answers

What does infrared microscopy help to identify in a fingerprint?

Chemical residuals Signup and view all the answers

Which component is NOT typically found in secretions that form fingerprints?

Carbon Black Signup and view all the answers

Study Notes

Forensic Serology: Blood

Blood Biochemistry and Blood Type: Blood biochemistry is explained in terms of blood type.
Blood Stain Analysis: Methods for analyzing suspected bloodstains are described.
Blood Spatter Interpretation: Techniques for interpreting blood spatter patterns are explained.

Blood on the Suspect

Blood Identification: Methods for determining if a substance is blood are explained.
Human vs. Animal Blood: Tests to differentiate human and animal blood are detailed.
Blood Source Identification: Determining whose blood is present is a key forensic objective.
Crime Scene Reconstruction: Blood spatter patterns can help reconstruct events at the crime scene.

Blood Composition

Blood Percentage: Blood constitutes about 8% of body weight.
Blood Plasma: The fluid portion (55% by weight) is mostly water, proteins, waste products of metabolism, and nutrients for cells.
Blood Cells (45% by weight): Includes various types, mainly red blood cells (erythrocytes) for oxygen transport, white blood cells (lymphocytes, phagocytes) for immune response, and platelets for blood clotting.
Blood Serum: Serum is the liquid that separates from blood when a clot is formed.

Erythrocytes

Size and Shape: Erythrocytes (red blood cells) are approximately 7.8 microns in diameter, with a biconcave shape and lack a nucleus.
Principal Function: Oxygen transport via haemoglobin proteins, which bind 4 oxygen molecules per protein.
Carbon Dioxide Transport: Carbonic anhydrase efficiently transports CO2 in the blood for removal from lungs.

Blood Typing

Antigens: Red blood cells have surface proteins (antigens).
Common Antigens: 30 commonly occurring antigens, with additional rarer ones.
A-B-O System: A fundamental blood typing system.

ABO Blood Types

Four Blood Types: A, B, AB, and O.
Antigen Locations: A antigens are on type A cells, B antigens are on type B cells, both on type AB, and neither on type O.
Population Distribution (Singapore): Approximate percentages for each blood type.

Blood Types and Love

Blood Type-Based Love: The notion that blood type determines love is incorrect and disproven.

Antibodies

Structure and Function: Antibodies (immunoglobulins) constitute about 20% of blood plasma. They bind to foreign objects (antigens) recognized as "alien".

Serum Antibodies

Specificity: Serum contains antibodies targeted at specific surface antigens.
Immune Response Basis: The antigen-antibody interaction underpinning the immune response.
Antibody-Antigen Matching: Anti-A antibodies react to A antigens, and Anti-B antibodies react to B antigens.

Agglutination

Blood Mixing: Mixing blood types A and B causes agglutination (clumping) due to Antibody-Antigen interactions.
Blood Transfusions: Blood transfusions have strict blood type matching requirement to prevent agglutination, leading to blood clotting.

Agglutination - Specific Example

A Blood Type Reactions: Blood cells with type A antigens do not clump or react with Anti-B antibodies.
B Blood Type Reactions: Blood cells with type B antigens do clump or react with Anti-B antibodies.

Blood Type Distribution (Singapore)

Rh Factors: Presence/absence of D antigen defines Rh positive (Rh+) or Rh negative (Rh-) status.
Prevalence: Rh+ prevalence in Singapore is ~85%.

Bio-Identification

ABO Not Unique: ABO blood type is not a unique identifier.
More Complex Typing: Additional blood typing methods (e.g., O Rh negative typing) exist to improve identification accuracy.
Reduced Probability: These techniques are less reliable than DNA fingerprinting and can establish innocence but not guilt.

Presumptive Tests for Blood

Benzidine Test: A presumptive blood test (now outdated) used for identifying the presence of blood.
Kastle-Meyer Test: A chemical test for blood, based on the peroxidase property of blood.
Phenolphthalein: A reagent in the Kastle-Meyer test.
Luminol Test: A sensitive test for blood using the peroxidase reaction. Used at crime scenes.

Luminol Test - Methodology

Crime Scene Use: Used to identify possible blood traces at crime scenes.
Sensitivity: Highly sensitive, detecting minute quantities of blood.

Chemical basis of the Kastle-Meyer Test

Chemical Principles: The test is based on the peroxidase activity of blood to catalyze the oxidation of a chemical, causing a color change.
False Positives: Other substances can also cause positive results for the test.

Kastle-Meyer Test Example

Results: Shows a visible positive result indicating the presence of a blood stain.

Precipitin Test

Rabbit-Based Antibody Production: Injecting human blood into rabbits produces anti-human antibodies (anti-sera).
Commercial Availability: Human anti-sera are available commercially.
Eliminating Animal Blood: Anti-sera can eliminate animal blood from an investigation.

Precipitin Reaction

Antigen-Antibody Interaction: When anti-sera (antibodies to human blood) meets human blood components (antigens), a precipitin line forms in the medium where both are mixed.

Why do we want to know about animal blood?: Case Example

Real World Application: Blood type and blood pattern analysis helped in an actual court case.
Differentiation Crucial: The test established a DNA match instead of blood type.

Blood Spatter Analysis Techniques

Is it Blood?: Presumptive tests (luminol, Kastle-Meyer) determine if a substance is blood.
Blood Type: Blood typing gives an overview of blood types.
Species Identification: Precipitin tests identify the species of blood.
DNA Identification: DNA analysis identifies the person who shed the blood.

Blood Patterns in Forensics

Blood Pattern Analysis: Examine patterns to reconstruct the sequence of events.
Blood Velocity Impact: Analyzing patterns to determine the velocity (low, medium, or high) at which the blood hit a surface.
Directionality: Determine the impact location and angle by examining blood spatter.

Blood Droplet Patterns: Examples

Impact Angle Calculation: The shape of the blood impact (e.g., circular or elongated) assists in calculating impact angles at the crime scene.
Convergence Point: Locating blood's point of origin by tracing back lines of blood droplets.

Lord Lucan Case (1974)

Case Summary: A high-profile homicide case, where the suspect vanished.
Crime Scene Details: Bloodstain evidence, suspect's actions, and the circumstances surrounding the event, were crucial elements of the investigation.
Timeline: Lord Lucan's whereabouts on the night of the murder are vital for reconstructing the incident.

Her Story (Nanny)

Timeline: The nanny's activities leading up to and following the murder are important for reconstructing the incident.

Blood and the Case of Lord Lucan

Blood Type Evidence: Blood type analysis revealed that the victims and suspects had the following blood types.

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Description

Explore the critical aspects of forensic serology related to blood. This quiz covers blood biochemistry, stain analysis, spatter interpretation, and identification techniques crucial for crime scene investigations. Delve into the composition and significance of blood in forensic science.