Intro to scientific and investigative techniques

turning diameter

The diameter of a circle that a car will make when the steering wheel is fully turned.

trabecular bone

The spongy inner portion of the bone.

transfer evidence

Evidence that is created by contact or interaction.

trash marks

marks made on copies because of defects in a copier or printer

triangulation

Estimating the location of a device based on the relative signal strength received at three or more receivers.

refractive index

The degree to which a sample bends or refracts light.

remodeling

The process of bone shape changes.

random match probability

The probability that another sample collected at random will share the exact same characteristics as the item or evidence in question.

prosecution

In criminal law, the government representative.

prosecutorial bias

bias that favors the prosecution’s position

prostate-specific antigen

a substance that is used to confirm the presence of seminal fluid

pseudoscience

another term for junk science

psychological autopsy

A postmortem evaluation of a person’s behavior and state of mind at and near the time of death.

pubic symphysis

A portion of the pelvis useful in determining the biological sex of an individual.

puparial

a stage in the life cycle of an insect that follows the larval stage (here, maggot)

probable cause

A reasonable basis of belief or suspicion of a crime being committed.

propagation reaction

A reaction or process that moves in a direction like a flame front.

polymerase chain reaction

A process used to replicate DNA at targeted loci.

perimortem

Events that occurred very near to the time of death.

opiates

Substances derived from the opium plant or that are chemically similar to morphine.

opinion evidence

Testimonial evidence in which an expert offers an opinion based on analysis or data.

opioids

synthetic opiates

optical bridge

A method of linking two microscopes into a single comparison microscope system.

azoospermia

Condition in which seminal fluid does not contain sperm cells.

abductive reasoning

The process of reasoning and thinking in which known pieces of evidence are considered to produce
a theory that represents the most likely and usually the simplest explanation.

accidental marks

Marks that arise from wear or random interaction, such as on shoe soles

accidental whorl

a type of whorl pattern in fingerprints

Accreditation

the process that ensures that laboratories are following standard protocols and procedures set forth by the accrediting body

acid phosphatase

a group of enzymes that laboratories are following standard protocols and procedures set forth by the accrediting body

Adjudicated

the settlement of a legal matter

admissibility

Allowing something (physical or testimonial) to be admitted as evidence in a legal proceeding.

Adversarial system

the process in which the merit of opposing sides is evaluated and settled by argument

algor mortis

Cooling of the body that occurs after death.

alkaloids

A group of plant-based drugs such as cocaine, morphine, and caffeine.

allelic ladder

A set of reference base pairs that are used to calibrate DNA analyses.

allometry

Patterns of relationships between bone lengths that can be used to estimate stature.

amorphous

Unordered, without organization. Glass is an amorphous substance.

amplicons

The amplified DNA that results from the polymerase chain reaction proces

amylase

A family of enzymes that break down starches and sugars. They are targeted in tests for saliva.

analogs

Compounds purposely synthesized to have similar effects as controlled or illegal drugs.

analyzer

In polarizing light microscopy, a second polarizing filter.

ancillary

Associated with; for example, digital evidence is often part of a criminal investigation even if the data itself is not central to the commission of a crime.

angle of impact

Acute or internal angle formed by the direction of a blood drop and the plane of the surface it strikes.

anisotropic

A substance that does not have the same refractive index throughout.

annealing

n the polymerase chain reaction cycle, binding of free nucleotides with short tandem repeat loci on open
DNA strands

anorexic

Drugs that suppress appetite.

antemortem

Before death.

Anti-Drug Abuse Act

An extension of the Controlled Substances Act meant to control analogs.

Apocrine gland

A type of sweat gland

Aqueous

A system or environment that is based on water.

arch

A type of pattern in fingerprints.

area of convergence

A point or area to which a bloodstain pattern can be projected on a two-dimensional surface. It is
determined by tracing the long axes of well-defined bloodstains within the pattern back to a common point or area.

area of origin

A three-dimensional point or area from which the blood that produced a bloodstain originated. Determined by projecting angles of impact of well-defined bloodstains back to an axis constructed through the point or area of convergence.

arson

Intentional setting of a fire.

asyphyxia

Interruption of the oxygen flow to the brain.

autopsy

Postmortem dissection of a human body.

back draft

An eruption of flame when oxygen is suddenly reintroduced to an oxygen-depleted zone.

backscattered electrons

In scanning electron microscopy, electrons scattered off the surface and used to generate an image.

back spatter

Blood directed back toward the source of energy or force that caused the spatter. Back spatter is often associated with entrance gunshot wounds.

ball powder process

A method of making gunpowder propellants by dropping a heating mixture into water.

base pairs

In DNA, A-T or C-G nucleotides.

bath salts

A term for synthetic stimulants.

becke line

A line visible under a microscope between a sample and the immersion liquid. How it moves as a function of defocusing and focusing is useful for refractive index measurements.

bias

an inclination, conscious or unconscious, to interpret evidence and draw conclusions that favor one result over another.

bifurcation

A fingerprint ridge feature in which ridges divide.

biological profile

A collection of data from skeletal remains, such as size, shapes, estimation of stature, and unique features of the bones.

biometric identifiers

Physical features of a body considered unique to an individual.

birefringence

The difference in the refractive indices of a material that has two refractive indices.

black box studies

Studies that use blind samples to determine how a methodology performs across many examiners and conditions.

blank

a sample that does not contain any of the compounds or materials associated with a specific analysis.

blasting cup

A device used to initiate a detonation.

blast wave

Zone(s) of compressed air and hot expanding gases created by an explosion.

blind sample

a sample provided to an analyst with a composition that is known to the submitter but not to the analyst.

blood alcohol concentration

The concentration of alcohol in blood, usually expressed as a percent and used to determine if a person is legally intoxicated.

breath alcohol

The concentration of ethanol in exhaled breath that can be used to estimate the blood alcohol concentration.

breathalyzer

A device used to measure the amount of alcohol in exhaled breath.

breech face marks

Marks on the base of a cartridge of ammunition created when the cartridge is driven backwards into the back of the chamber.

buccal swab

A cotton swab swiped along the inside of the cheek to collect DNA.

burden of proof

the responsibility of establishing proof within a legal setting

caliber

 The dimension of the barrel of a gun (nominally). Also refers to the size of a bullet.

cannabinoids

Substances that produce physiological effects similar to the active ingredients in marijuana (tetrahydrocannabinol).

carboxyhemoglobin

Hemoglobin that is bound to carbon monoxide instead of oxygen.

carfentanil

An extremely potent synthetic opioid.

carrion

 The decaying flesh of an animal.

cartridge

A self-contained unit of ammunition.

case manager

The person at a forensic laboratory who oversees and organizes different types of forensic testing on evidence from one scene or one crime.

castoff patterns

Bloodstain pattern created when blood is released or thrown from a blood-bearing object in motion.

cathinone

The active ingredient in Khat leaves; stimulant.

cause of death

The disease or injury that started an irreversible chain of events leading to death.

cellular network

A network of zones associated with towers that create the basis of a phone network.

centerfire

An ammunition cartridge in which the primer is mounted in the center of the base.

central blood

Blood sample taken from the heart during autopsy.

central pocket whorl

A type of whorl pattern in fingerprints.

certification

a process that includes written test and sometimes laboratory work that if passed ensures that the analyst can perform work at the level specified by the certification body.

chain of custody

The documented process the evidence goes through from the point of gathering to the final presentation in court. Intended to ensure that there has been no tampering with or altering of the evidence.

chemical energy

A form of energy that is stored in chemical bonds.

chemical heat

Heat released by chemical reaction.

christmas tree stain

A staining procedure used to highlight sperm cells for visualization under a microscope.

chromogenic substance

A compound that can react to form a colored substance.

chromosomes

Found in the nucleus of cells and composed of DNA. They carry genetic traits.