Forensic Science

Locard's Principle of Exchange

Locard's Principle of Exchange

contact between people and objects during a crime can result in a transfer of material

direct evidence

evidence (if true) that proves a fact (eyewitness account)

circumstantial evidence

evidence that does not directly support a fact (blood stain or fingerprint)

physical evidence

an object used to support elements of a crime

biological evidence

organic matter used to support elements of a crime

class evidence

evidence that narrows an identity to a group of persons or things

individual evidence

evidence that narrows identity to a single person or thing

trace evidence

a small amount of physical or biological evidence

crime-scene investigation team

police officers, detectives, crime-scene investigators, medical examiners, and specialists

crime-scene investigation

recognize, document, photograph, and collect evidence

first-responding officer

identify extent of crime scene, secure the scene, and separate witnesses

primary crime scene

location of where the crime took place

secondary crime scene

alternate location where additional evidence can be collected

crime-scene investigator

processes crime scenes (recognize, document, and preserve evidence)

triangulation

mathematical method of calculating the location of an object based on the position of other objects

paper bindle

folded paper used to hold evidence

chain of custody

document that records how and when evidence has been handled

datum point

a permanent, fixed point of reference used in mapping a crime scene

crime-scene reconstruction

forming a hypothesis of the sequence of evidence before, during, and after the crime

forensic laboratory

where evidence is analyzed

detective

develops a possible crime-scene scenario

toxicology

the study of poisons, toxins, drugs, and other substances people use for medical, recreational, or criminal purposes

handling substance evidence

process it, weigh it, separate it, identify it

forensic toxicology

science of determining relationship between exposure to a substance and toxic or lethal effects of exposure on humans

poisons

natural or manufactured chemicals that can cause severe harm

toxins

naturally occurring poisonous substances living things produce

toxicologist

examines the effects of harmful substances on the body, establishes cause and effect of exposure, and develops treatments and techniques for detection

toxicity

degree to which a substance is harmful to a person at a given time

factors of toxicity

dose, duration, nature of exposure, interactions, by-products when broken down or metabolized

questions for toxicological testing

which substances?

illegal components?

how much of each?

presumptive testing

preliminary chemical tests performed by first-responding officers to identify a substance (does not provide positive confirmation)

confirmatory testing

multistep chemical process that provides a positive identification of a substance

colorimetric testing

most common form of presumptive testing that results in a color change

chromatography, mass spectrometry, capillary electrophoresis, wet chemistry

most common forms of confirmatory testing

acute poisoning

poisoning caused by a high dose over a short period of time; symptoms present themselves immediately

chronic poisoning

poisoning caused by low doses over long periods of time; symptoms present themselves gradually

heavy metals

poisonous metallic substances that are ingested, inhaled, or absorbed through the skin or mucous membranes

mercury poisoning

heavy metal example

lethal gas

gases that cause bodily harm or death when inhaled

carbon monoxide and hydrogen cyanide

lethal gases examples

lethal injections

injection of a lethal substance in the body that causes bodily harm or death

potassium and sodium pentothal

lethal injection examples

herbicide

chemical substance that controls plants; can be deadly in humans

pesticide

chemical substance that controls insects and rodents; can be deadly in humans

aldrin and dieldrin

pesticide examples

glyphosate mixture

herbicide example

rattlesnake venom and ricin

toxin examples

five classes of drugs

based on reactions

five classes of drugs are

narcotics, depressants, stimulants, hallucinogens, anabolic steroids

tolerance

amount of drug that creates an effect

addiction

compulsive drug craving and use

dependency

intense drug craving without withdrawal symptoms

five schedules of drugs (CSA Act)

based on acceptance for medical use and potential for dependency

illegal substances

drugs that are not used medically

heroin and LSD

illegal drug examples

controlled drugs

legal drugs that are restricted because of their effects and high potential for dependency and abuse

hallucinogen

illegal drugs that affect perception, thinking, self-awareness, and emotions (effects: elevated heart rate, high blood pressure, dilated pupils)

LSD

hallucinogen example

narcotic

addictive, sleep-inducing drugs that depress the CNS and suppress pain (effects: dizziness, weakness, confusion, contracted pupils)

heroin and morphine

narcotic examples

controlled substances include

stimulants, narcotics, depressants, and anabolic steroids

stimulants

highly addictive drugs that increase feelings of energy and alertness while suppressing appetite (effects: high blood pressure and rapid heart rate)

meth and cocaine

examples of stimulants

depressants

drugs that relieve anxiety and produce sleep (effects: slowed heart rate, slowed breathing, slurred speech, loss of coordination, coma)

alcohol

nervous system depressant that can be highly addicting and can impair judgment

anabolic steroids

substance that promotes cell growth and division; used by bodybuilders and to treat low levels of testosterone

doping

use of substances to enhance athletic performance

drug combinations

can have compounding effects and lead to accidental death

biological profile

estimation of the deceased's sex, age, stature, and ancestry, along with diseases and injuries, as derived from analysis of skeletal remains

diaphysis

the shaft of a bone

epiphysis

the unattached end of a bone that eventually becomes fused with the bone shaft

forensic anthropology

the use of skeletal anatomy to identify remains for legal purposes

epiphyseal plate

area of cartilage between the shaft and cap of an immature bone responsible for the lengthening of bone

ossification

the processes that replaces cartilage with bone by the deposition of minerals

osteoperosis

loss of bone density that can result in increased risk of fractures

skeletal trauma analysis

the investigation of bones and the marks on them to uncover a potential cause of death

cartilage

connective tissue that wraps ends of bones for protection and prevents scraping against each other

ligaments

connective tissue that links two or more bones

tendons

connective tissue that attaches muscle to bone

full bone growth

males: 19 or 20

femailes: 16 or 17

bones and geography

compare amounts of strontium and isotopes in teeth to geographical regions

male shape of eye

more square

female of shape of eye

more rounded

male shape of mandible

more square shaped

female shape of mandible

more V-shaped

male upper brow ridge

thicker and larger

female upper brow ridge

thin and slender

male occipital protuberance

prominent

female occipital protuberance

less prominent

male frontal bone

low and sloping

female frontal bone

higher and more rounded

male surface of skull

rough and robust

female surface of skull

smooth and gracile

male zygomatic process

extends to or past ear opening

female zygomatic process

stops short of ear opening

male mastoid process

larger and more robust

female mastoid process

smaller