1. How are incidences involving ballistics and arson investigated?
Essential Question:
How are incidences involving ballistics and arson investigated?

2. Introduction
Forensic ballistics: the science of analyzing firearm usage in crimes
Ballistic evidence helps explain:
What type of firearm was used.
The caliber of the bullet.
The number of bullets fired.
Physical position of the shooter.
Whether a weapon was fired recently.
If a firearm was used in previous crimes.

3. Types of Legal Firearms
1. Handguns and pistols: designed to be handheld (rifled to increase accuracy)
Revolvers: has a cylinder that hold the bullets (usually 6)
Manually reloaded
Semiautomatic: shoots one cartridge at a time
Reloads automatically
Fully automatic weapons keep firing as long as the trigger is held down
Revolvers: six shooters
Rifling decreases wobbling in flight by putting a spin on the projectile like throwing a football
Pic- Walther P99 German semiautomatic pistol

4. Types of Legal Firearms
Rifling: Make spiral grooves to make a bullet spin and thereby have greater accuracy over a long distance.
2. Rifles
Longer barrel
Butt stock to steady the firearm and minimize kickback
Greater range & accuracy than a handgun
Pic-hunting rifle

5. Types of legal firearms
3. Shotguns
Like rifles but shoot pack of shot or spherical pellets
Barrel is not rifled
Bottom Pic-browning A-5 semi automatic shotgun

6. Types of Legal Firearms
4. Air guns or BB guns
Pellets propelled by pressurized air, spring compression, battery operated or carbon dioxide cartridges
Pic-bb pistol w/ CO2 magazines

7. Ammunition
Ammunition consists of a cartridge case, primer, propellant, and a projectile (bullet)
Ammunition is named by its length and diameter (caliber)
over 300 kinds of ammunition for just handguns
Diameter is known as caliber

8. Ammunition Most bullets made of lead Vary in shape & size
Can be coated with brass, copper, or steel
Vary in shape & size
Hallow points: hole causes bullet to deform upon impact in order to decrease penetration & cause greater harm

9. Forensic Science: Fundamentals & Investigations, Chapter 17
Assignment for Today
Work on Ballistics Vocab
Forensic Science: Fundamentals & Investigations, Chapter 17

10. How a Firearm Works
Firing pin of gun hits the base of the cartridge, igniting the primer powder.
The ignited primer powder sparks through the flash hole, causing the main propellant supply (gunpowder) to ignite
The pressure of the explosion pushes the bullet from the casing into the barrel.
The bullet follows the lands and grooves spiraling out of the barrel.

11. Caliber
Caliber: measure of the diameter of the bullet cartridge (also the diameter of the firearm’s barrel or bore)
Measured in hundredths of an inch.
Common calibers include 0.22, 0.25, 0.357, 0.38, 0.44, and 0.45.

13. Grooves, Lands, & Rifling
Grooves and lands in the barrel of a gun produce the twisting that adds accuracy.
The rifling leaves a pattern on the bullet which can be traced back to the specific gun

14. Bullet Features To Analyze
Individual characteristics
Scratches or striae on the bullet caused by gun barrel
A microscope is used to identify & compare these marks
Class characteristics
Weight
Dimensions
Shape
Type of bullet
Used to help determine the type of ammunition used
Lands and grooves
Used to identify the make and model of a weapon
Striae used to match two bullets or match a bullet to a firearm
Use size, weight, shape, and dimensions to determine the type of ammunition
Ex: .357 magnum weighs 10.2g
Ex: a standard 9mm weighs 6.5g
Lands and groves
Ex: the .32 caliber S & W handgun has five lands and grooves with a right hand twist
Ex: the .32 caliber Colt has 6 lands and grooves with a left-hand twist.
Matching grooves (indentations)
Matching lands (elevations)

15. Cartridges Consist of: bullet & case that contains the powder & primer
Most cartridges have primer in the center (centerfire); some use primer on the circumference of the base (rimfire)

16. Cartridge Features To Analyze
Class characteristics:
Dimensions
Rimfire or centerfire
Head stamp (imprint)
Individual characteristics:
Impression from firing pin
Breech marks & Extractor Marks
Marks left by gun as bullet is fired
Scratches caused by movement in magazine or chamber
Striae used to match two bullets or match a bullet to a firearm
Use size, weight, shape, and dimensions to determine the type of ammunition
Ex: .357 magnum weighs 10.2g
Ex: a standard 9mm weighs 6.5g
Lands and groves
Ex: the .32 caliber S & W handgun has five lands and grooves with a right hand twist
Ex: the .32 caliber Colt has 6 lands and grooves with a left-hand twist.

18. Methods of analyzing ballistics
Ballistic gel block
Water tank
Gauze packing
Rubber balls

19. Gunshot Residues GSR Found on shooter: Traces on the victim as well
Particles of unburned powder and traces of smoke from gunshot
Found on shooter:
Hand
Arm
Face
Hair
Clothing
Traces on the victim as well
GSR can be used to determine the distance between the victim and the shooter
Easily transferred
GSR particles blow back onto the shooter

20. Forensic Science: Fundamentals & Investigations, Chapter 17
GSR Testing
Greiss Test
Test for presence of nitrite
Check for color change: orange-red
Sodium Rhidizonate
Test for the presence of lead
Check for color change: purple
Forensic Science: Fundamentals & Investigations, Chapter 17

21. Gunshot Residues
Residues from gunshots = particles of unburned powder and traces of smoke
They can leave a trace on the hand, arm, face, hair, or clothing of the shooter.
They can also leave a trace on the victim.
Chemical testing often can detect residue even if removal is attempted.
The distance from the victim to the shooter can be determined by examination of the residue pattern on the victim.

22. Trajectory Two reference points are needed to define the trajectory.
Path of bullet
Horizon
Wind shield
Distance along path of
bullet to window, 23.9”
Distance along
horizon to
window, 23.5” y x
60 feet
Two reference points are needed to define the trajectory.
Investigators can figure the shooter discharged the firearm somewhere along that line.

23. Trajectory Reference points can be bullet holes in objects or victims.
An entry point and exit point on a victim can be used.
Gunshot residue or spent cartridge casings can be less specific reference points.
Investigators can use lasers to trace a straight-line path to help determine the position of the shooter.

24. Bullet Wounds
Why do entrance wounds tend to be smaller than exit wounds?
If the bullet penetrates clothing, what can fibers embedded in the wound indicate?
Where is gunshot residue usually found?
If the gun is fired with the muzzle touching the victim’s skin, what telltale mark may show up?
Will larger or will smaller caliber bullets tend to lodge within the body rather than passing through? Why?

25. Arson Determine possible cause of fire Establish point of origin
Accident, natural or deliberate?

26. Arson: Terms to Know
Arson: crime of maliciously, voluntarily & willfully setting fire to property
Fire: produced when a substance undergoes rapid oxidation involving heat and light.
Flashpoint: lowest temperature at which a substance can ignite
Color of flames can be used to tell temp. of fire

27. Arson: Terms to Know Point of Origin: location where fire started
Burn patterns: noticeable patterns created by fire as it burns
Fire normally burns in a V-shaped pattern
Accelerants: substances, such as gasoline, paint thinner, & alcohol, that accelerate the burning process

28. The FIRE TRIANGLE represents the three elements needed for fire to occur:
heat, fuel, and oxygen
FUEL
OXYGEN
HEAT

29. The Fire Triangle
Oxygen: enough O2 must be present to sustain combustion (at least 16%)
Fuel: some sort of flammable fuel must be present
Heat: enough heat must be produced to ignite the fuel source

30. Motives for Arson Insurance Fraud
Attempt to harm person &/or their property
Revenge: accounts for 50% of arson cases
Conceal crime: robbery, murder
Terrorism
Pyromania

31. Arson Indicators 2 or more points of origin
2 separate, non-related fires
Trailers = ribbon or linear pattern of spread of fire: indicates that fire followed an accelerant
Odors: gas, kerosene or other accelerants
Furnishings & valuables removed
Locked windows & blocked doors

32. Arson: Methods of Detection
Physical evidence
Dogs: smell for accelerants
Portable gas detections aka “sniffers”
Gas chromatography: chemical analysis of accelerants & burned remains

33. Causes of Accidental Fires
Heating system
Dryer
Lightning
Electronics
Smoking

34. Forensic Science: Fundamentals & Investigations, Chapter 17
Assignments for Today
Fire Crossword Puzzle
Begin Ballistics & Arson Review
Forensic Science: Fundamentals & Investigations, Chapter 17

35. Reminder: No talking during Notes (Lecture)
You need to remain silent & pay attention during notes
You SHOULD NOT be talking to your neighbors or having “silent” conversions across the room
Raise your hand if you have a question or comment
If I see or hear your talking:
Verbal warning
Silent lunch
Classroom detention
Leave room & write-up
CELL PHONES NEED TO BE PUT AWAY!
Depending on prior disciplinary actions

36. Investigating Criminal Bombing
Evidence:
Presence of scattered bomb fragments
Trained dogs detect traces of explosive material
Need safety precautions for crew due to:
structural instability of buildings
dangerous materials such as glass and metal
flammable or toxic substances
Always a possibility that a second device
May kill or maim those who respond to the explosion

37. Criminal Bombing Richard Reid Shoe bomb attempt
Suspicious individual: loner, fidgety, sweaty
Result: we take shoes off at the airport
Eric Rudolph
1996 Centennial Olympic Park bombing
Suspicious unattended bag
Killed 1 and injured 111 people
Generally require preventative measures
Reid- self proclaimed Al-Qaeida
Rudolph-Extremist Christian movement
-Olympic bombing- originally suspected the officer who found the bomb. He was investigated by FBI for 3 months and ridiculed by the media for longer. Found Rudolph hiding in the woods of North Carolina-he bombed some abortion clinics 2 years later and was linked back to the 1996 bombing.

38. Criminal Bombing Ted Kaczynski, the Unabomber Timothy McVeigh
Lived in a mountain cabin in Montana
Mail bombs
Killed 3 and injured 23 people
Timothy McVeigh
Oklahoma City bombing
Truck Bomb
Killed 168 and injured over 800 people
Ted: Sent a narration of his motives to the FBI- They in turn got it published in the Times and Washington Post- Ted’s family recognized his views and beliefs.

39. Forensic Science: Fundamentals & Investigations, Chapter 17
End of Unit 5 Notes!
Reminders:
Do the Ballistics & Arson Review!
Study your notes, worksheets, and handouts!
Ballistics & Arson Review Lab
Forensic Science: Fundamentals & Investigations, Chapter 17

40. 4 Corners You have two minutes to contemplate this question:
Which of these factors of investigating criminal bombing is most important?
Crew Safety: protecting those investigating the bombing
Suspect profiling
Attending to victims
Collecting/Preserving PhysicalEvidence
Find the corner of the room with the answer you chose

41. Jigsaw Read the text provided to your group
Create a small poster with vital information about arson to present to the class
Poster must include: Use Markers
A title
a picture or diagram related to your topic
A brief summary of topic and specific terminology of note
Be prepared to present your topic during the last 15 minutes of class

42. Ballistics and Arson Georgia Performance Standards
SFS4 Students will evaluate the role of ballistics, tool marks and evidence of arson in
forensic investigation.
a. Identify firearm lab tests used to distinguish the characteristics of ballistics and
cartridge cases.
b. Analyze the physics of ballistic trajectory to predict range of firing.
d. Evaluate possible indicators of arson and criminal bombing.