Forensic Science: Firearms, DNA, and Digital Evidence

What is firearms identification mainly concerned with?

Determining whether a bullet or cartridge was fired by a particular weapon.

What is the primary safety rule when handling a firearm?

ALWAYS KEEP YOUR FIREARM POINTED IN A SAFE DIRECTION.

What must happen to the hands of a potential shooter to detect primer residues?

Swabbings must be taken of the hands.

What is the most important instrument for comparing fired bullets?

The comparison microscope.

What characteristic does evidence that can be traced to a common source possess?

Individual characteristics.

What characteristic does evidence associated with a group possess?

Class characteristics.

What type of image cannot be viewed directly?

A virtual image.

What instrument bombards a specimen with electrons to produce a highly magnified image?

The Scanning Electron Microscope (SEM).

What are the two most useful physical properties of glass for forensic comparisons?

Density and refractive index.

What set the guideline for determining the admissibility of scientific evidence?

The decision in Frye v. United States.

What Supreme Court case addressed the use of evidence affidavits by forensic examiners?

Melendez-Diaz v. Massachusetts (2009).

What are the three layers of the hair shaft?

The cuticle, the cortex, and the medulla.

What are the two types of hair DNA useful in forensic analysis?

Nuclear DNA and mitochondrial DNA.

What category of substances depresses the functions of the central nervous system?

Depressants.

Give two examples of depressants classified as antianxiety drugs.

Valium and Xanax (alprazolam).

What drug classification includes amphetamines and cocaine?

Stimulants.

How does the analytical technique of Spectrophotometry work?

It measures the quantity of radiation that a particular material absorbs.

What analytical technique combines gas chromatography and mass spectrometry?

GC/MS (Gas Chromatography/Mass Spectrometry).

What type of absorption spectrum provides a unique 'fingerprint' of a chemical substance?

An infrared absorption spectrum.

What is the collection guideline for items containing volatile solvents?

They must be packaged in an airtight container.

What is the primary constituent of opium?

Morphine.

What is the federal drug-control law known as?

The Controlled Substances Act.

What are the four chemical building blocks that make up DNA?

Guanine (G), Adenine (A), Thymine (T), and Cytosine (C).

In the structure of DNA, what base pairs with Adenine (A)?

Thymine (T).

What is the purpose of Polymerase Chain Reaction (PCR)?

A technique for replicating or copying a portion of a DNA strand.

What are the short DNA segments containing repeating sequences called?

Short Tandem Repeats (STRs).

What national system maintains databases of DNA profiles?

CODIS (Combined DNA Index System).

What is the difference between a phenotype and a genotype?

A phenotype is an observable characteristic; a genotype is the combination of genes.

How is the amount of shared DNA with a match measured?

In CentiMorgans (cM).

Why are arson investigations complex?

The perpetrator has thoroughly planned the act and the destruction is extensive.

How do investigators recover volatile accelerant residues from fire debris?

By heating the airtight container to drive off the residue into the headspace.

What technique increases sensitivity by trapping accelerant vapor?

Vapor concentration technique.

What are the three mechanisms of heat transfer during a fire?

Conduction, radiation, and convection.

What is the primary characteristic of an explosion?

Rapid combustion accompanied by the creation of large volumes of gases.

What are the two classifications of high explosives?

Primary explosives and secondary explosives.

What must happen to debris collected from an explosion scene?

They must be packaged in separate air-tight containers.

What term describes the physical components of the computer?

Hardware.

What is the main storage component in a personal computer?

The hard disk drive (HDD).

What are the three types of latent data?

Swap file data, temporary files, and unallocated space.

What is a single 'one' or 'zero' in the binary system?

A bit.

What is the purpose of placing a seized mobile device in a Faraday bag?

To prevent remote communication that could alter evidence.

What is a logical extraction of a mobile device?

A snapshot of the file system.

What is a physical extraction of a mobile device?

A duplicate of data located on the mobile device.

What specific card associates a mobile phone with the subscriber's mobile network?

A SIM (Subscriber Identification Module) card.