Forensic Analysis of Broken Windows

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Questions and Answers

What is a critical factor in determining the method of entrance in robbery cases related to window fragments?

The type of glass used

The color of the glass

The origin of the breakage (correct)

The size of the fragments

What characteristic of a bullet hole indicates that the shot was fired from the opposite direction?

A smooth hole with no damage

A large and jagged hole

Even flake distribution around the hole

Numerous small flakes of glass blown away (correct)

How can one determine if a shot was fired at an angle from the left side of a windowpane?

Excessive flaking on the right side of the pane (correct)

Excessive flaking on the left side of the pane

No flaking observed

Equal flaking around the hole

What type of damage does a bullet fired from a long distance typically cause?

Similar to damage caused by a stone Signup and view all the answers

In analyzing broken windows for criminal cases, what should be done with the glass fragments?

Collect and piece them together Signup and view all the answers

What is the result of a shot fired perpendicular to the windowpane?

Evenly distributed flake marks around the hole Signup and view all the answers

What kind of impression traces may be studied in cases like theft or robbery?

Foot, tool, and tire impressions Signup and view all the answers

What causes excessive flaking on the left side of a windowpane?

A bullet fired at an acute angle from the left Signup and view all the answers

What is the primary origin of soil constituents?

Mechanical and chemical decomposition of rocks Signup and view all the answers

Which mineral is primarily a form of silica and known for being colorless and transparent?

Quartz Signup and view all the answers

What chemical component is present in calcite?

CaCO3 Signup and view all the answers

What role do clay minerals play in soil?

They enhance soil moisture retention Signup and view all the answers

Which of the following is a product of the decomposition of primary minerals?

Clay minerals Signup and view all the answers

Which mineral is also known for its resistant layer structure?

Mica Signup and view all the answers

Organic constituents in soil are primarily formed from what?

Accumulation of organic matter Signup and view all the answers

Which of the following is a characteristic of clay soil?

It can become hard and adherent on heating Signup and view all the answers

What is a characteristic of cast coins that makes them easily detectable?

Pitted and uneven surface Signup and view all the answers

How are struck coins created?

By applying pressure with steel dies on a metal blank Signup and view all the answers

Which etching fluid is used for aluminum restoration?

Glycerin, nitric acid, and hydrofluoric acid Signup and view all the answers

What is the purpose of etching fluid?

To restore tampered serial numbers Signup and view all the answers

Which solution is suggested for wrought iron and forged iron?

A mixture of hydrochloric acid, water, and cupric chloride Signup and view all the answers

What percentage of hydrochloric acid is used for tin etching?

10% Signup and view all the answers

Which metal requires aqua regia for serial number restoration?

Gold and platinum Signup and view all the answers

What factor can vary significantly in soil composition?

Parent rock and natural activities Signup and view all the answers

What is a key issue when determining if a person fired a gun?

The presence of gunpowder residue Signup and view all the answers

What is the primary component percentage of potassium or sodium nitrate in Black Powder?

75% Signup and view all the answers

Which type of powder is the most widely used propellant?

Smokeless Powder Signup and view all the answers

What constituents are found in Black Powder?

Charcoal, Sulfur, and Potassium Nitrate Signup and view all the answers

What role do stabilizers play in Smokeless Powder?

They reduce side reactions Signup and view all the answers

Where could nitrates be expected to be found after the explosion of gunpowder?

In or around the wound Signup and view all the answers

What happens if there are slight differences in the composition of Black Powder?

It can lead to uncontrollable side reactions Signup and view all the answers

Which stabilizers are sometimes used in Smokeless Powder?

Nitrobenzene and Vaseline Signup and view all the answers

What is a limitation of the diphenylamine - paraffin test?

The test cannot determine the source of nitrate. Signup and view all the answers

Which of the following substances can contain nitrate oxidizing agents?

Tobacco and explosives Signup and view all the answers

What might cause a person to test positive for nitrates without firing a gun?

Shielding themselves from gunfire Signup and view all the answers

Which factor is NOT a reason a person might test negative for nitrates despite having fired a gun?

High humidity levels Signup and view all the answers

What is the maximum timeframe for conducting the diphenylamine - paraffin test after a shooting in the Philippines?

Two days Signup and view all the answers

Why is careful handling of clothing removed from a gunshot victim essential?

To ensure powder residues do not become dislodged Signup and view all the answers

What type of gun is more likely to cause leakage of powder when fired?

Old weapons with poorly fitting breeches Signup and view all the answers

What can be the effect of wind velocity on nitrate detection after shooting?

It can lead to dislodging powder residues. Signup and view all the answers

Study Notes

Analysis of Broken Windows

Examining window fragments in robbery cases plays a vital role in determining whether glass was broken from the inside or outside.
Analyzing crack patterns and piecing fragments together helps determine the original position of the glass.

Broken Window Caused by Bullet Holes

Bullet hole edges are sharpest when fired with a strong charge.
A bullet fired from a long distance will break the pane similarly to a stone.
A close-range shot produces a crater-like appearance with numerous glass flakes blown away—the bullet was fired from the opposite direction of missing flakes.
Evenly distributed flakes indicate a perpendicular shot.
More flake marks on one side indicate an angled shot from the opposite direction.

Broken Window Caused by Fist or Stone

No details about broken windows caused by fists or stones were found in the text.

Chapter VII

The chapter focuses on traces left by criminals through impressions such as footprints, tool marks, and tire tracks in cases like theft and robbery.

Cast Coins

Cast coins are easy to detect due to their pitted and uneven surface, rounded edges, and poor imitations.

Struck Coins

Struck coins are created by striking or stamping a metal blank through pressure with steel dies, resulting in well-executed impressions.
They can be difficult to detect as weight, specific gravity, and composition may be similar to genuine coins.
Careful comparison of smaller details is crucial for identification.

Tampered Serial Numbers

Etching liquid is often used to restore tampered serial numbers.
The choice of etching fluid depends on the metal's structure.

Etching Fluids

Cast iron and cast steel: 10% sulfuric acid and potassium dichromate.
Wrought iron and forged iron: Solution no. 1 (hydrochloric acid, water, cupric chloride, alcohol) and Solution no. 2 (15% nitric acid).
Aluminum: Glycerin, nitric acid, and hydrofluoric acid.
Lead: 3 parts glacial acetic acid and one part water.
Stainless steel: Dilute sulfuric acid or 10% hydrochloric acid in alcohol.
Copper, brass, silver, and copper alloys: Ferric chloride, hydrochloric acid, and water.
Tin: 10% hydrochloric acid.
Zinc: 10% sodium hydroxide.
Silver: Concentrated nitric acid.
Gold and platinum: Aqua regia (3 parts hydrochloric acid and one part nitric acid).
Wood: Steam jet.

Soil

Soil originates from the decomposition of rocks and is greatly varied in composition.
Soil analysis is often overlooked by investigators despite its importance.
Soil varies significantly even in small geographical areas.
Soil composition changes with depth.

Constituents of Soil

Primary minerals: Undecomposed rock fragments, ranging from stone to pebbles, sand, and silt.
Quartz: A common mineral found in igneous, metamorphic, and sedimentary rocks.
Calcite (Limestone): White, reacts with acid, releasing carbon dioxide. Abundant in calcareous soil, often found in sedimentary rock.
Feldspar: A silicate of Aluminum, Sodium, Barium, Calcium, or Potassium.
Dolomite Limestone: Similar to limestone but is a white mineral extracted from sedimentary rock.
Mica: A mineral with thin, flexible layers resistant to heat.
Other primary minerals: Gypsum, Talc, Kaolinite, Limonite, Magnetite
Clay minerals: Formed by decomposing primary minerals. Found nearly all soils and constitute most heavy soils. Imparts cohesiveness and plasticity, becoming hard and adherent when heated.
Organic constituents: Highly variable, crucial for soil identification. Agricultural land is rich in organic matter. Peat and muck soils are primarily formed from decaying organic matter.
Chemical tests: Treating soil samples with hydrochloric acid and ethanol can reveal color changes, gas evolution, and other reactions, aiding in soil identification.

Firearms

Three key problems arise in firearm investigation.
- Determining whether a person fired a gun with bare hands.
- Establishing the gunshot range.
- Determining the time of firing based on the gun residue.

Gunpowder

Two main gunpowder types are commonly used:
- Black Powder is an older type with inherent defects
- Smokeless Powder is the most widely used propellant.
Black Powder is composed of charcoal, sulfur, and potassium or sodium nitrate.
Smokeless Powder consists of cellulose nitrate, glyceryl nitrate, and stabilizers.
- Stabilizers like nitrates, bichromates, oxalates, Nitrobenzene, Graphite, and Vaseline are added to reduce side reactions.

Possible Locations of Nitrates When Gunpowder Explodes

Nitrates are found in both gunpowder types and are expected to be found in the following:
- Residue in the barrel of the gun
- In or around bullet wounds
- Clothing of the person fired upon at close range

Limitation of the Diphenylamine - Paraffin Test

This test is not specific for nitrates; it only detects oxidizing agents.
Other substances containing nitrates or oxidants, such as fertilizers, explosives, tobacco, firecrackers, urine, cosmetics, and detergents, can produce false positives.

Possibilities of False Positive and False Negative Tests

A person may test positive for nitrates even without firing a gun due to contact with gunpowder particles from another person.
A person may test negative for nitrates even after firing a gun due to:
- Direction of the wind
- Wind velocity
- Excessive precipitation
- Wearing gloves
- Using chemicals to remove nitrates

Powder Leakage

Powder leakage is more likely to occur with old weapons with loose breech mechanisms or revolvers.

Timing of Diphenylamine - Paraffin Tests

The test should be administered immediately after a shooting incident and not later than 72 hours.
Nitrates can be detected for up to three days, even after washing hands.
In the Philippines, the maximum time for conducting the test is two days due to heavy perspiration.

Determining Gunshot Range

The text has limited information on determining the gunshot range.

Collecting, Preserving, and Packing Clothing

Clothing should be handled carefully to prevent dislodging powder residues.
A large area around the bullet entrance should be available for testing.

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Description

This quiz explores the forensic analysis techniques used to examine broken windows in criminal cases. It focuses on identifying whether glass was broken from inside or outside, as well as the implications of bullet holes and other impacts. Understanding these details is crucial for reconstructing crime scenes.

Forensic Analysis of Broken Windows - Chapter VII

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