Summary of "Introduction to Forensic Ballistics"

Topic and purpose

This video is an introduction to forensic ballistics: how investigators use bullets, cartridge cases, gunshot residue (GSR), trajectories and wound information as physical evidence to reconstruct shootings and link firearms to crimes.

Definition and scope

Ballistics is the science of the motion, behavior and effects of projectiles (in this context: bullets). For forensic purposes, ballistics is divided into distinct phases, each yielding different kinds of evidence and analytical approaches.

Classical phases of ballistics

1. Internal ballistics

Begins when the trigger is pulled and ends when the bullet exits the barrel.
Concerns propellant combustion, pressure buildup and the bullet’s acceleration inside the barrel.
Understanding this phase helps interpret barrel-related markings and other evidence produced before the bullet leaves the firearm.

2. External ballistics

Begins when the bullet exits the barrel and travels through air.
Focuses on trajectory, speed, range and environmental effects.
Analysis can reveal firing distance, shot angle and shooter position.

3. Terminal ballistics

Begins at impact and examines how the bullet penetrates and damages the target or object.
Evaluates depth of penetration, fragmentation and damage patterns to infer firearm/munition type, range and target position.

Forensic subfields and techniques

Bullet identification
- Bullets pick up rifling marks (lands and grooves) from the barrel that can link a projectile to a specific firearm.
Cartridge-case identification
- Fired cases bear marks from the firing pin, extractor and ejector mechanisms that can be matched to a gun.
Gunshot residue (GSR)
- Firearm discharge leaves burnt and unburnt particulate residue; detecting GSR on hands, clothing or nearby surfaces can indicate who fired a gun and help estimate range.
Trajectory analysis
- Mapping bullet paths establishes angle of entry, shooter–target distance and relative shooter location.
Wound ballistics
- Studies entry/exit wounds, fragmentation and tissue damage to estimate caliber/type of ammunition, shooting distance and victim/shooter positioning.

Historical and professional contributors

Note: names below reflect the video’s captions (some spellings or forms may be inaccurate).

Dr. Calvin Goddard (captioned as “Calvin Godard”)
- Foundational figure in forensic ballistics; introduced the comparison microscope in the 1920s and helped solve high‑profile cases (e.g., the St. Valentine’s Day Massacre).
Alexander Lassani (captioned)
- Described as a 19th‑century French forensic scientist who linked barrel rifling and powder residue to firearm identification and range estimation.
Luke S. May (captioned)
- Cited for contributions to tool‑mark identification, firearm examination and law‑enforcement training.
Dr. Vincent JM Deo (captioned)
- Forensic pathologist/ballistics expert and author of reference material on gunshot wounds and forensic techniques.
Major General Julian S. Hatcher
- Firearms expert and author of Hatcher’s Notebook; contributed to understanding ballistic coefficients, stability and terminal effects.
Alfred A. Bot (captioned)
- Described as a pioneer in tool‑mark identification, comparative analyses and courtroom testimony.
Dr. Jio Sharma (captioned)
- Mentioned as an influential forensic ballistics educator who introduced modern techniques and served as a professor.

Typical forensic-ballistics workflow (stepwise)

Secure and document the scene
- Photograph and record locations of bullets, cartridge cases, bullet holes and bodies before moving anything.
Collect and preserve physical evidence
- Recover bullets and fragments in labeled containers.
- Collect fired cartridge cases and note their positions.
- Take GSR swabs from suspects’ hands and relevant clothing; package to avoid contamination.
- Preserve clothing and biological samples for wound analysis.
Perform ballistic examinations in the lab
- Bullet and cartridge-case comparison:
  - Examine rifling marks on bullets and firing-pin/extractor/ejector marks on cases.
  - Use a comparison microscope to compare evidence with test-fired specimens.
- Test-fire suspected firearms into a recovery medium to obtain reference bullets and cases.
GSR and residue analysis
- Chemically or microscopically test for GSR particulates on hands, clothing and surfaces to assess firing involvement and estimate distance.
Trajectory reconstruction
- Map entry/exit holes and use markers (strings, rods, 3D tools) to establish path, angle and approximate shooter location.
Wound-ballistic analysis
- Examine entry/exit wounds, fragmentation and tissue effects to estimate range and projectile interaction.
Integrate findings
- Correlate bullet/cartridge matches, GSR results, trajectory reconstruction and wound analysis to build a coherent reconstruction for investigation and court presentation.