Forensic Science Lecture Notes

Forensic Science Flashcards

What is the application of science to criminal matters called?

Forensic Science

What is the role of a CSI (Crime Scene Investigator)?

Maintain chain of custody, learn from forensic scientists, and may have a science background.

What are the two primary roles of a Forensic Scientist?

Work in a laboratory setting and testify in court as an expert witness.

List the steps of the Scientific Method.

Purpose/objective, Hypothesis, Methodology, Results, Conclusion(s).

Name three types of scientific measurement errors.

Gross errors, Systemic errors, Random errors.

What are the first steps in a preliminary crime scene examination?

Secure the scene and note observations, looking for the MO and crime pattern.

Describe a spiral search pattern.

Starting from the outside and spiraling inward towards the center of the crime scene.

Describe a line search pattern.

Combing the scene back and forth in lines, inch-by-inch.

Describe a grid search pattern.

Forming a grid by searching back and forth and left to right.

Describe a zone search pattern.

Searching the scene by specific areas or zones.

Why are sketches and context (type of crime, scene) important in documenting a crime scene?

They provide clues to what evidence should be present.

What is Chain of Custody?

A tracking system of evidence and who has access to it.

What is the maximum magnification power of a compound microscope and what type of image does it produce?

450x; Inverted image

What is the key feature of a comparison microscope?

Allows side-by-side comparison of specimens.

What type of specimens are analyzed using a polarizing microscope?

Minerals, metals, and rocks (very reflective materials).

What is a key feature of the stereomicroscope?

A large space between the stage and specimen, producing an upright image.

What is the function of a microspectrophotometer?

Measures the intensity of wavelengths in the light spectrum.

What does a scanning electron microscope study?

Electron emissions from a specimen.

What two qualities must evidence possess?

Material and probative.

What is the difference between physical and nonphysical evidence?

Physical evidence consists of objects/things; nonphysical evidence is verbal testimony.

What is the difference between real and demonstrative evidence?

Real evidence is generated by criminal activity; demonstrative evidence is created to explain real evidence.

What is the difference between known and unknown evidence?

Known evidence has a known source or ownership; unknown evidence has an unknown origin.

What is the difference between individual and class evidence?

Individual evidence comes from only one source; class evidence comes from several sources.

Are wear patterns individual or class characteristics?

Individual

Are tear patterns individual or class characteristics?

Class

What does IAFIS stand for and what is its purpose?

Integrated Automated Fingerprint Identification System; used for fingerprint identification.

What does CODIS stand for and what type of information does it contain?

Combined DNA Index System; contains DNA profiles.

What does NIBIN stand for and what type of information does it contain?

National Integrated Ballistics Information Network; contains ballistics information.

What is the composition of blood?

Plasma (55%) and cells (red blood cells) (45%).

Name two preliminary tests for locating blood on objects.

Luminol and Fluorescein.

Name two confirmatory tests used in blood identification.

Teichmann and Takayama.

How does surface texture affect blood spatter?

Hard, non-porous surfaces result in less spatter; rough surfaces result in irregular stains with serrated edges.

What does the tail of a blood droplet indicate?

The direction of travel.

Describe low-velocity blood spatter.

Spatter with a greater diameter.

Describe forward spatter.

Spatter projected outward and away from the source (exit wound).

Describe back spatter.

Blood projected backward from the source (entrance wound).

Describe cast-off spatter.

Blood projected due to the motion of a weapon.

Describe arterial spray spatter.

Spatter from a major blood vessel.

What are the main differences between a coroner and a medical examiner?

A coroner is an elected official (not necessarily an MD); a medical examiner is an appointed official and must be an MD.

What is the difference between cause of death and manners of death?

Cause of death is the immediate cause, while manner of death is the circumstances (e.g., homicide, natural, accidental).

List the manners of death.

Homicide, natural, accidental, suicide, and undetermined.

What are some aspects examined during an external autopsy?

Wounds, bruises, and scratches.

What are some aspects examined during an internal autopsy?

Bodily fluids, blood toxicity, organs, and stomach content.

List four classifications of violent deaths.

Mechanical, chemical, electrical, and thermal.

What are algor mortis, rigor mortis, and livor mortis and when do they occur?

Algor mortis is the cooling of the body, rigor mortis is the stiffening of the body, and livor mortis is the cessation of blood circulation; these occur in the early PMI (Postmortem Interval).

What is forensic anthropology?

The application of osteology (study of bones) and skeletal identification to legal matters.

How many bones are in the adult human skeleton?

206 bones

What are the functions of bones?

Grow and change over time.

Name some bones used for identification of skeletal remains.

Cranium, mandible, clavicle, sternum, vertebra, humerus, radius, ulna, pelvis, femur, tibia, fibula.

How can you tell if a specimen is bone?

Presence of Haversian canals.

How can you tell if a specimen is human bone versus non-human bone?

Plexiform bones indicate non-human origin.

What are some factors used to determine age of death from skeletal remains?

Dentition, bone development, and pubic bones.

What are some characteristics used to determine gender from skeletal remains?

Greater sciatic notch and pubic symphysis.

What are friction ridges?

Raised portions of the outer layer of skin that form rows that curve and loop across the finger.

What is dactyloscopy?

The science of comparing friction ridges.

What are the three classifications of fingerprints?

Latent, patent, and plastic.

List some pattern types of fingerprints.

Plain arch, tented arch, radial loop, ulnar loop, plain whorl, central pocket loop whorl, double loop whorl, accidental whorl.

Name a few techniques used for the detection and visualization of fingerprints.

Fingerprint dusting, Reflected UV Imaging System, Chemical Fingerprinting.

What is hair?

An outgrowth of the skin layer.

What is the structure from which hair originates and grows?

Follicle

What protein makes up hair?

Keratin

What are the three stages of hair growth?

Anagen, catagen, and telogen.

What determines dark hair color?

Eumelanin

What determines light hair color?

Phaeomelanin

What does the medulla look like in human hair?

Interrupted, fragmented, or absent.

What does the medulla look like in animal hair?

Continuous (generally).

What can be determined from the structure of hair?

Human vs. non-human, part of the body, color, disease/treatment.

What types of DNA can be extracted from hair?

Nuclear DNA (nucDNA) and mitochondrial DNA (mitDNA).

How are textile fibers transferred?

Easily transferred and may be multiple transferred.

List three types of fibers.

Natural, synthetic, and semi-synthetic.

Name some aspects of fiber morphology?

Type, size, cross-section, diameter, color/dye, crimp, delusterants.

What is refractive index?

A measure of how much light bends when entering a medium.

What are illicit drugs?

Abused drugs or controlled substances.

What are licit drugs?

Drugs with a recognized medical use as defined by the FDA.

List four classifications of drugs and their effects.

Stimulants (increase mood and energy), depressants (sedative effects), hallucinogens (change perception of reality), narcotics (sleep-inducing).

What are the steps in illicit drug analysis?

Screening test, separation test, and confirmatory test.

What is pharmacology?

The study of drug interactions and effects on people.

What is the difference between toxicology and forensic toxicology?

Toxicology is the study of beneficial and harmful effects; forensic toxicology involves cases in the criminal justice system.

Name four routes of drug administration.

Oral ingestion, injection, inhalation, suppository.

List different types of injections.

Intramuscular, subcutaneous, intravenous, and intradermal.

Name a few ways a drug is eliminated from the body.

Vomit, urinate, sweat, exhale.

Name three field sobriety tests.

Walking & turning, standing on one foot, and horizontal gaze nystagmus.

What is DNA?

Deoxyribonucleic acid.

Where is mitochondrial DNA located?

Mitochondria

Where is nuclear DNA located?

Cell nucleus.

What are genes?

Genetic code contained within portions of the chromosomes.

What are genotypes?

Genetic makeup for a trait.

What are phenotypes?

Expressed traits; physical manifestation.

What are alleles?

Different forms of a gene.

What is PCR?

A means of amplifying DNA for analysis.

Name the different blood types.

A, B, AB, O.

What types of firearms are designed to be held and operated with one hand?

Hand guns (pistols, revolvers, semi-automatics).

What types of firearms are designed to be fired while resting on a shoulder and require two hands to operate?

Long guns (shotguns, rifles, machine guns).

Why is spinning important in the rifling process?

Spinning imparts angular momentum and keeps the object on its intended trajectory.

What are stippling patterns and what do they indicate?

Unburned gunpowder and barrel residues; they help determine the distance of fire.

What is a tool mark?

A scratch or other microscopic marking left by the action of a tool on an object.

What is matter?

Anything that has mass and occupies space.

What are the states of matter?

Solid, liquid, gas/vapor, and plasma.

What is the difference between physical and chemical properties of a substance?

Physical properties describe behavior without altering composition; chemical properties describe behavior when reacting with other substances.

Name some physical properties of glass used in forensics characterization.

Refractive index and density.