Forensic Firearms and Ballistics: Crime Scene Analysis and Drug Testing

Firearms

Any weapon which will or is designed to expel a projectile through explosive force, including the frame or receivers of such objects, including silencers.

Forensic ballistics/firearms analysis

The examination of evidence from firearms that may have been used in a crime.

Recovery of firearms

The process of collecting firearms used in crimes as well as related items, including bullets and cartridges, which is extremely important.

Major categories of firearms

Four major categories: Handguns, Shotguns, Rifles, and Submachine guns.

3D Printed guns

A new addition to consider in the category of firearms.

Handguns

A compact weapon that can be fired using only one hand, originally designed for cavalry.

Revolver

A type of handgun first invented by Colt, usually holds 6 shots and is more accurate than semiautomatic handguns.

Semiautomatic Pistols

Handguns that use the recoil of firing to eject the cartridge and reload, more complicated than revolvers and can jam easily.

Silencers

A device attached to a handgun to reduce noise generated by firing.

Rifles

Firearms designed to be fired from the shoulder with a barrel and butt stock, more loosely regulated than handguns.

Shotguns

Firearms meant to be fired from the shoulder that shoot a single projectile or a cluster of small pellets in a circular pattern.

Submachine Guns

Firearms that fire automatically like a machine gun but use pistol ammunition, often issued to military, security details, and police.

Ballistics

The study of bullet motion.

Internal ballistics

Events inside the firearm.

External ballistics

The behavior of a bullet outside the firearm before it strikes the target.

Terminal ballistics

What happens when the bullet strikes a target.

Self-contained cartridges

Cartridges that contain the bullet, the outer casing, gunpowder, and primer, all in one, developed by firearms manufacturers.

Firearms analysts

Professionals who study bullet or cartridge cases to link them to the gun that fired them based on microscopic marks.

Cartridge

Contains the casing, powder, primer, & bullet

Caliber

The internal diameter of the gun barrel, measured in hundredths of an inch in the US and in millimeters in Europe

Rifling

Spiral grooves cut into the bore of firearms to improve accuracy

Grooves

The incised depressions in rifling

Lands

The areas between the grooves in rifling

Rifling Marks

Microscopic marks left by rifling that can be matched to a particular gun

Serial Numbers

Every gun has a serial number stamped into the metal frame, which must be maintained by all gun dealers

Acid etching

A method to restore serial numbers using hydrochloric acid and other chemicals

Magnaflux method

A method that uses a magnet with iron filings to provide a shadow of the serial number

IBIS

Integrated Ballistics Identification System, a system for comparing and matching bullets and cartridges

NIBIN

National Integrated Ballistic Information Network, used only for criminal investigations

eTrace

ATF's web-based application that tracks the purchase and use of firearms from violent crimes

Congruent Matching Profile Segments (CMPS)

A computer algorithm developed by NIST that uses 3D maps to match individual segments of crime scene bullets

Gunshot Residue (GSR)

Residue created when a firearm is fired, composed of particles of explosive primer, propellant, and components of the bullet/cartridge

Presumptive Tests

Tests used to identify the presence of a suspected substance, usually cheaper and easier than confirmatory tests

Confirmatory Tests

Tests that provide positive identification of a substance

Sodium Rhodizonate test

A presumptive test that provides a color reaction indicative of the presence of lead and barium

Diphenylamine test

A presumptive test that detects the presence of nitrates, producing a blue color if nitrates are present

SEM

Scanning Electron Microscopy, used to detect lead, barium, and antimony in samples

Energy-dispersive X-ray spectroscopy (EDS)

A technique that allows for elemental composition analysis

Chemical Abbreviations

Common chemical symbols used in GSR analysis: Ba - Barium, Fe - Iron, Pb - Lead, Sb - Antimony, Na - Sodium, Cl - Chloride, K - Potassium, Ti - Titanium, Si - Silicon, Al - Aluminum

What is forensic drug analysis?

The application of analytical chemistry techniques to identify and quantify unknown, possibly illicit substances.

What does forensic toxicology analyze?

It identifies the type and quantity of substances in biological samples and answers questions about drug involvement in deaths or impairments.

What are some applications of forensic toxicology?

Postmortem forensic toxicology, human performance toxicology, and forensic drug testing.

How many Americans were current illicit drug users as of 2020?

37.3 million Americans aged 12 or older.

What percentage of people aged 12 and over have used illegal drugs or misused prescription drugs in the last year?

21.4% (59.277 million people).

What was a major cause of fatalities related to drug use in 2009?

Drug overdoses and brain damage linked to long-term drug abuse, killing an estimated 37,485 people.

What are illicit drugs?

Terms for many abused substances, including controlled substances regulated by federal and state laws.

What are presumptive drug tests used for?

To determine the possible presence of a drug in the field.

What is a limitation of presumptive tests?

They may generate false positives and require confirmatory testing.

What does the Marquis Color Test indicate?

Heroin and morphine turn the solution purple; amphetamines turn it orange-brown.

What does the Scott Reagent Test detect?

Cocaine, which turns the solution blue, with a positive result being a pink over blue reaction.

What is the advantage of color tests in drug analysis?

They are simple, inexpensive, field-deployable, and provide quick results.

What is the importance of confirmatory testing?

It ensures accurate identification of controlled substances using multiple testing methods.

What is the difference between qualitative and quantitative tests?

Qualitative tests identify the type of drug; quantitative tests measure the amount present.

What are some methods used in drug analysis?

Infrared Spectroscopy, Mass Spectrometry, Gas Chromatography, and Color Tests.

What is the role of quality assurance in drug analysis?

To ensure test results correspond to the exhibit, using measures like separate samplings and good laboratory practices.

What percentage of traffic deaths in the U.S. were related to alcohol in 2010?

Over 31%.

What is the legal blood alcohol concentration (BAC) limit for drunkenness in the U.S.?

0.08.

What is the relationship between breath alcohol concentration and blood alcohol concentration?

The concentration of alcohol in the lungs is related to the concentration in the blood with a ratio of 1 to 2100.

What is the purpose of portable Breathalyzers?

To quantify the amount of alcohol in a suspect's blood.

What is the fuel cell testing method in breath analysis?

It generates an electrical signal in response to the breakdown of alcohol, measuring the current based on alcohol concentration.

What does North Carolina require for confirmatory alcohol testing?

The use of headspace gas chromatography (HSGC) to quantitatively determine alcohol concentration.

What are the three basic fingerprint patterns identified in the 'Samudrika Shastra'?

Sankha (loops), chakra (whorls), seep (arches)

Which ancient civilization was among the first to use fingerprints for identification?

China

What was the purpose of fingerprints in ancient China?

Used as signatures on documents

Who was William James Herschel and what was his contribution to fingerprinting?

A British colonial officer who learned about fingerprinting in India and published his findings in England.

What significant fingerprint classification system was developed in India?

The Henry System of fingerprint classification

What is the significance of the Calcutta Anthropometric Bureau established in 1897?

It was the world's first fingerprint bureau.

What are the three fundamental principles of fingerprints?

1. Individual characteristic; 2. Remain unchanged during a lifetime; 3. Can be systematically classified.

What does it mean that a fingerprint is an individual characteristic?

No two fingerprints possess exactly the same set of ridge characteristics.

How many ridge characteristics can be noted in an average fingerprint?

As many as 150 ridge characteristics.

What are friction ridges?

Tiny raised lines found on the palm side of fingers and thumbs.

What percentage of the population has loop fingerprint patterns?

Approximately 65%.

What is the ACE-V method in fingerprint analysis?

A method consisting of Analysis, Comparison, Evaluation, and Verification.

What is the purpose of the Automated Fingerprint Identification System (AFIS)?

To scan and digitally encode fingerprints for identification.

What significant update did the FBI make to AFIS in 1999?

The overhaul led to the Integrated Automated Fingerprint Identification Systems (IAFIS).

What is the largest AFIS database in the USA?

IAFIS, which contains nearly 50 million fingerprint records.

How do modern AFIS systems compare fingerprints?

By analyzing minutiae (identification points) and using search algorithms.

What is the role of a trained fingerprint expert in the AFIS process?

To examine possible matches and make the final verification of a fingerprint's identity.

What are the three levels of detail in fingerprint examination?

1. Overall direction of ridge flow; 2. Path of specific ridges; 3. Shapes of ridge structures, edges, textures, and pore positions.

What are the three types of fingerprints found at a crime scene?

Patent Prints, Plastic Prints, Latent Prints

What surfaces are suitable for developing latent fingerprints?

Hard and nonabsorbent surfaces such as glass, mirrors, tile, and painted wood.

What is the purpose of fingerprint powders in fingerprint development?

To contrast with the surface examined for better visibility.

What are the types of fingerprint powders used?

Black powder, gray powder, magnetic sensitive powders, and fluorescent powders.

What is Super Glue fuming used for in fingerprint analysis?

It is a chemical treatment used to develop fingerprints by creating fumes that visualize prints.

What is the composition of Super Glue used in fuming?

Approximately 98-99% cyanoacrylate ester.

How long should the fuming chamber be maintained for Super Glue fuming?

Up to 6 hours.

What is Ninhydrin and how is it used in fingerprint analysis?

Ninhydrin is a chemical developer that reacts with amino acids in sweat to produce a purple-blue product known as Ruhemann's purple.

What are some challenges associated with 'touch' DNA recovered from fingerprints?

Variable amounts of cellular material, DNA extraction destroying fingerprints, and contamination from non-sterile collection methods.

What can sweat from a single fingerprint detect in drug screening?

At least four different drug classes: THC, cocaine, opiates, and amphetamines.

What did the 2009 National Academy of Sciences Report conclude about fingerprint analysis?

Only nuclear DNA analysis has been rigorously shown to consistently demonstrate a connection between an evidentiary sample and a specific individual.

What was the finding of the PCAST 2016 Report regarding fingerprint analysis?

Fingerprint analysis is 'foundationally valid' but requires error rates to be reported.

What was the false-positive error rate found in an FBI study regarding fingerprint analysis?

As high as 1 in 306 cases.

What is Rule 702 of the Federal Rules of Evidence regarding expert testimony?

It allows a qualified expert to testify if their knowledge helps understand evidence, is based on sufficient facts, and is derived from reliable principles and methods.

What is the significance of the US v. Llera Plaza case in fingerprint analysis?

Initially excluded testimony by a latent print examiner under Daubert rules, but later admitted the evidence.

What did the 2017 appeals court in North Carolina determine about fingerprint evidence?

It was wrong to admit fingerprint evidence in a criminal case due to lack of reliability testing.

What is the role of SWG FAST in fingerprint analysis?

It is a Scientific Working Group that established standards for friction ridge analysis.

What limitations are placed on examiners regarding source identification in fingerprint analysis?

Examiners cannot assert absolute certainty or imply infallibility in their conclusions.

What should examiners avoid using to describe their confidence in fingerprint conclusions?

Expressions like 'reasonable degree of scientific certainty' or similar assertions.

What are the four groups in the ABO blood system?

A, B, AB, O

What does a positive Rh factor indicate?

The presence of a protein found in Rhesus macaques.