Forensic Science Cheat Sheet

The core ideas of Forensic Science distilled into a single, scannable reference — perfect for review or quick lookup.

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Quick Reference

Locard's Exchange Principle

The foundational forensic principle stating that every contact between two objects results in a transfer of material. When a person comes into contact with a place or another person, physical evidence is both left behind and carried away.

Chain of Custody

The documented, unbroken trail showing the seizure, custody, control, transfer, analysis, and disposition of physical evidence. It ensures evidence integrity and admissibility in court.

DNA Profiling

A technique that analyzes specific regions of an individual's DNA to produce a genetic profile unique to that person (except identical twins). Short tandem repeat (STR) analysis is the most commonly used method in criminal investigations.

Fingerprint Analysis (Dactyloscopy)

The examination of friction ridge patterns on fingertips for identification purposes. Fingerprints are categorized by pattern types (loops, whorls, arches) and compared using minutiae points such as ridge endings, bifurcations, and dots.

Forensic Toxicology

The study of the effects of drugs, poisons, and other chemical substances on the human body, particularly in the context of determining cause of death, impairment, or exposure in legal investigations.

Ballistics and Firearms Examination

The analysis of firearms, ammunition, and projectile evidence. Examiners compare striations on bullets and firing pin impressions on cartridge cases to link recovered evidence to a specific weapon.

Digital Forensics

The recovery, investigation, and analysis of material found in digital devices such as computers, smartphones, and cloud storage. It involves preserving data integrity while extracting evidence relevant to criminal or civil cases.

Forensic Pathology

A branch of medicine focused on determining the cause and manner of death through autopsy and examination of the deceased. Forensic pathologists classify deaths as natural, accidental, suicide, homicide, or undetermined.

Trace Evidence Analysis

The examination of small or microscopic materials transferred during a crime, including fibers, hair, glass fragments, paint chips, soil, and pollen. Trace evidence can link a suspect to a victim or crime scene.

Forensic Serology

The analysis of biological fluids such as blood, semen, saliva, and sweat found at crime scenes. Serologists perform presumptive and confirmatory tests to identify the type of fluid before DNA analysis is conducted.

Key Terms at a Glance

AFIS:Automated Fingerprint Identification System; a database for storing and matching fingerprint records electronically.

Algor Mortis:The postmortem decrease in body temperature used to help estimate the time of death.

Autopsy:A systematic medical examination of a body after death to determine cause, manner, and mechanism of death.

Ballistics:The study of projectiles in motion, applied in forensics to the analysis of firearms and ammunition evidence.

Bloodstain Pattern Analysis:The interpretation of bloodstain shapes, sizes, and distributions to reconstruct the events of a violent crime.

Chain of Custody:The documented sequence of possession and handling of evidence from collection through court presentation.

CODIS:Combined DNA Index System; the FBI's national DNA database for matching crime scene profiles to known individuals.

Comparison Microscope:An instrument with two optical paths allowing side-by-side comparison of two specimens, commonly used in firearms and toolmark examination.

Corpus Delicti:The body of evidence that proves a crime has been committed, literally meaning 'body of the crime.'

Cyanoacrylate Fuming:A technique using superglue vapors to develop latent fingerprints on nonporous surfaces.

Daubert Standard:The legal criterion for admitting expert scientific testimony in federal courts, requiring reliable methodology and relevance.

DNA Profiling:A forensic technique that compares specific regions of DNA to identify individuals or link suspects to crime scenes.

Exemplar:A known standard sample used for comparison against questioned evidence, such as a known handwriting sample or test-fired bullet.

Forensic Anthropology:The study of human skeletal remains to determine identity, cause of death, and other legally relevant information.

Forensic Entomology:The use of insect biology and behavior, especially colonization patterns on remains, to estimate time since death.

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