What is The Evidence Log?

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Glossary

The Evidence Log covers two kinds of evidence: the evidence behind the scenes of everyday systems — consumer behavior, game design, hiring, marketing, and media — and the evidence behind criminal investigations, forensic science, and true crime. This glossary defines the key terms from both worlds, because the same principles of evidence, data, and methodology apply whether you are analyzing a pricing strategy or a crime scene.

Understanding the vocabulary matters because precise language underpins the integrity of every conclusion. A chain of custody is not just a phrase — it is the documented sequence of evidence handling that determines whether a bloodstain, a digital file, or a latent fingerprint can be admitted at trial. An anchoring effect is not just a marketing term — it is a documented cognitive bias that explains why a price feels like a bargain. When these terms are misunderstood or misused, investigations fail, wrongful convictions occur, and consumers are manipulated without realizing it.

This glossary is maintained by The Evidence Log as a reference resource for readers, students, journalists, and investigators who want to understand the vocabulary of evidence — forensic, behavioral, and digital — as it is actually used. Each definition is written to be accessible without sacrificing accuracy, and where a technique has known limitations or has been subject to scientific controversy — such as bite mark analysis or microscopic hair comparison — we say so plainly.

Use this glossary alongside our case files and analyses to deepen your understanding of how evidence is collected, analyzed, and evaluated — whether in a criminal investigation or behind the scenes of the systems that shape everyday life.

Art & Cultural Crime

Due Diligence (Art): The investigation process a buyer, auction house, or institution undertakes to verify the authenticity, legal title, and provenance of an artwork before purchase. Due diligence failures — skipping provenance checks, ignoring red flags in documentation — are how stolen and forged works enter the legitimate market.
Provenance: The documented history of ownership of an artwork or cultural object, tracing its chain of custody from creation to the present. Provenance is the central evidentiary question in art crime — gaps or forgeries in provenance are often the only indication that a work was stolen, looted, or forged. Nazi-era looted art cases hinge almost entirely on provenance research.
Art Loss Register: A private database of stolen, looted, and missing art, antiques, and collectibles, maintained to help recover stolen works and deter trade in illicit cultural property. Auction houses and buyers consult the register as a due diligence step before purchase, though coverage is incomplete and many stolen works are never registered.

Cold Case Investigation

Cold Case: A criminal investigation that has gone unsolved for an extended period and is no longer being actively investigated, but remains open pending new evidence. Cold cases are revived when advances in forensic technology (especially DNA), new witness information, or re-examination of old evidence creates investigative leads that did not exist at the time of the original investigation.
John/Jane Doe: A placeholder name used for an unidentified person, living or deceased, whose identity is unknown to investigators. Unidentified remains cases are among the most persistent cold cases; modern forensic genealogy and DNA databases have begun resolving some that had been unidentified for decades.
CODIS: The Combined DNA Index System, the national DNA database maintained by the FBI that stores DNA profiles from convicted offenders, arrestees, and crime scene evidence. CODIS enables cross-jurisdictional DNA matching and has been the single most important tool in solving cold cases since its launch in 1998.

Consumer & Behavioral Economics

Anchoring Effect: A cognitive bias in which the first piece of information encountered (the 'anchor') disproportionately influences subsequent judgments and decisions. In pricing, exposing a consumer to an initial high price makes subsequent prices seem more reasonable by comparison — a tactic retailers exploit with 'original price' strikethroughs and 'compare at' labels.
Loss Aversion: The well-documented psychological principle, grounded in prospect theory, that losses feel roughly twice as painful as equivalent gains feel pleasurable. This asymmetry drives risk-averse behavior, free-trial marketing (where consumers resist 'losing' a product they already have), and the effectiveness of money-back guarantees.
Decoy Pricing: A pricing strategy in which a third, deliberately less attractive option is introduced to steer consumers toward a more expensive target option. The decoy is not meant to sell — it exists to make the target look like a better value. Classic example: a medium coffee priced just below a large, making the large appear to be a bargain.

Corporate Fraud & Whistleblowing

Qui Tam: A legal provision (from Latin 'qui tam pro domino rege quam pro se ipso') allowing a private whistleblower to file a lawsuit on behalf of the government against a party defrauding the government, and to receive a portion of the recovered funds. Qui tam actions under the False Claims Act are among the most powerful tools available to corporate whistleblowers.
Shell Company: A company that exists only on paper, with no real operations, assets, or employees. Shell companies are used for legitimate purposes (holding assets, mergers) but are also the primary vehicle for money laundering, tax evasion, and hiding the proceeds of corporate fraud. Tracing funds through layers of shell companies is the core of financial fraud investigation.
Ponzi Scheme: An investment fraud that pays returns to earlier investors using funds from newer investors rather than from legitimate profit. Named after Charles Ponzi, the scheme collapses when new investment slows or too many investors withdraw simultaneously. The evidence of a Ponzi scheme is typically in the accounting — consistent returns regardless of market conditions are a hallmark.

Crime Scene Investigation

Chain of Custody: The documented, unbroken sequence of every individual who handled, transferred, or stored a piece of evidence from the moment it was collected at a crime scene to its presentation in court. Any gap or ambiguity in the chain can render evidence inadmissible, as the defense can argue it was tampered with or contaminated. The O.J. Simpson trial remains the most famous example of chain-of-custody failures undermining a prosecution.

Cyber Sleuthing

Metadata: Data that describes other data — the creation date, location, author, and editing history embedded in files like photos and documents. Metadata has cracked cases where the visible content could not: a photo's GPS coordinates, a document's author field, or a file's creation timestamp can place a suspect at a scene or expose a fabrication.
IP Logging: The recording of IP addresses that access a system, service, or website, along with timestamps. IP logs are a foundational evidence type in cybercrime investigation — they can place a device at a location, establish a timeline, and link separate accounts. They are also circumstantial: an IP address identifies a device or network, not necessarily a person.
OSINT (Open Source Intelligence): Information gathered from publicly available sources — social media, public records, news, forums, leaked databases — and analyzed to build intelligence. OSINT is the foundation of much modern cyber sleuthing, allowing investigators to identify suspects, trace networks, and reconstruct events using only what is publicly accessible.

DNA & Biological Evidence

PCR (Polymerase Chain Reaction): A laboratory technique that amplifies a specific DNA region, producing millions of copies from a tiny original sample. PCR revolutionized forensic science by enabling DNA profiling from minute or degraded evidence — a single skin cell, a strand of hair, or a decades-old stain. Without PCR, touch DNA, ancient DNA analysis, and most modern cold case resolutions would be impossible.
Forensic Genealogy: A technique that uploads crime scene DNA to consumer genealogy databases (such as GEDmatch) to find partial matches with distant relatives, then builds family trees to identify a suspect. First used to identify the Golden State Killer in 2018, it has since solved dozens of cold cases. The method raises significant privacy concerns, as individuals who submit DNA to genealogy services may unwittingly expose relatives to investigative scrutiny.
Allele: One of two or more alternative forms of a gene at a given location (locus) on a chromosome. In forensic DNA profiling, examiners analyze specific loci where alleles vary significantly between individuals. The combination of alleles across multiple loci creates a DNA profile. The more loci examined, the smaller the probability that two unrelated individuals share the same profile, which is how forensic DNA can achieve match probabilities of one in trillions.
Touch DNA: DNA recovered from skin cells left behind when a person briefly touches a surface. Also called contact DNA or trace DNA, these samples contain very few cells and require amplification using PCR (Polymerase Chain Reaction) technology. Touch DNA has become increasingly important in cold cases, but its sensitivity also raises contamination concerns, as it can recover DNA from individuals who never directly touched the item.
CODIS: The Combined DNA Index System, maintained by the FBI. CODIS is the national DNA database that stores profiles from convicted offenders, arrestees, and forensic evidence from unsolved cases. It enables law enforcement to search a crime scene DNA profile against millions of records, linking serial offenders to multiple crimes and solving cases that had been cold for decades.

Digital Forensics

Digital Forensics: The recovery and analysis of data from electronic devices — computers, smartphones, servers, and storage media. Digital forensic examiners recover deleted files, analyze network traffic logs, trace IP addresses through anonymizing networks, and extract metadata from digital photographs. The discipline has become central to modern investigations ranging from financial fraud to terrorism.

Evidence Lifecycle & Chain of Custody

Chain of Custody: The documented and unbroken sequence of who handled a piece of evidence, when, and why, from collection through courtroom presentation. Breaks in the chain — undocumented transfers, unsecured storage, unaccounted-for time — can render evidence inadmissible, because the integrity of the evidence cannot be verified.
Spoliation: The destruction, alteration, or failure to preserve evidence, whether intentional or negligent. Spoliation can trigger legal sanctions, adverse inference instructions (where the court tells the jury they may assume the destroyed evidence was unfavorable), or case dismissal, because the lifecycle of evidence ended prematurely.
Brady Disclosure: The constitutional requirement, established by Brady v. Maryland (1963), that prosecutors disclose evidence favorable to the defense and material to guilt or punishment. Failure to disclose Brady material is a leading cause of wrongful conviction reversal — the evidence exists, but the lifecycle of evidence broke down at the disclosure stage.

Flawed Forensics & Junk Science

Bite Mark Analysis: A forensic technique that compares dental impressions left on skin to a suspect's teeth. Once widely admitted in court, bite mark analysis has been thoroughly discredited by subsequent research — the skin is a poor recording medium, marks distort over time, and examiners cannot reliably match marks to a single individual. Multiple wrongful convictions have been traced to bite mark testimony.
Hair Microscopy: The practice of comparing hair samples under a microscope to link a suspect to a crime scene. FBI reviews found that analyst testimony overstated the evidentiary value of hair comparison — which can exclude a source but cannot identify one — in over 90% of reviewed cases. Several resulting convictions have been overturned by DNA testing.
Confirmation Bias (Forensics): The tendency of forensic examiners to interpret ambiguous evidence in a way that confirms a prior hypothesis, often shaped by case context provided by investigators. Blind testing of forensic methods consistently shows that examiners given case context reach different conclusions than those who are not — evidence that contextual bias materially affects forensic findings.

Game Design & Player Psychology

Dark Patterns: User interface designs deliberately engineered to manipulate or deceive users into actions they did not intend, such as spending money, sharing data, or remaining engaged. Common patterns include 'grind' loops that make free play tedious while paid shortcuts bypass the friction, and 'roach motel' designs that make it easy to start a subscription but difficult to cancel.
Whale (Gaming): A player who spends significantly more than the average user on microtransactions. In free-to-play monetization models, a small percentage of whales typically generates the majority of revenue, a distribution pattern economists describe as the Pareto principle. This concentration of revenue is why game publishers optimize design around high-spending players rather than the median.
Variable Reward Schedule: A reward delivery system, borrowed directly from behavioral psychology (B.F. Skinner's operant conditioning research), in which rewards are delivered at unpredictable intervals rather than fixed ones. Variable schedules produce far higher and more persistent engagement rates than fixed schedules — the same mechanism that drives slot machine design and loot box mechanics.

Hiring & Workplace Analytics

Applicant Tracking System (ATS): Software used by employers to collect, sort, and filter job applications automatically. ATS platforms parse resumes for keywords, rank candidates by algorithmic match scores, and reject applications that fail to meet predefined criteria before a human ever reviews them. The filtering logic is opaque to applicants and is a major reason qualified candidates are filtered out for formatting or keyword reasons rather than qualifications.
Affinity Bias: The unconscious tendency to favor candidates who share similarities with the interviewer — alma mater, hobbies, background, or demographic traits. Affinity bias is a primary driver of homogeneity in hiring and contributes to the persistent finding that interviewers rate candidates more highly when they resemble themselves, regardless of job-relevant qualifications.
Unstructured Interview: An interview conducted without a fixed set of questions, allowing free-flowing conversation. Decades of industrial-organizational psychology research demonstrate that unstructured interviews are among the weakest predictors of job performance, far below structured interviews and work-sample tests, yet they remain the most common interview format due to misplaced interviewer confidence in their own judgment.

Interrogation & Confession

False Confession: An admission of guilt made by an innocent person, typically produced under coercive interrogation pressure, sleep deprivation, false evidence presentation, or the promise that confession will end the ordeal. False confessions are a leading documented cause of wrongful conviction, proven by DNA exonerations in dozens of cases.
PEACE Model: An investigative interviewing framework (Planning and preparation, Engage and explain, Account, Closure, Evaluate) developed in the UK as an alternative to coercive interrogation. The PEACE model seeks information rather than a confession and has been adopted widely outside the US, with evidence showing it produces more reliable information and fewer false confessions.
Reid Technique: A widely used interrogation method developed in the 1960s, structured around confrontation, psychological manipulation, and theme development to justify a confession. Research has shown the Reid Technique's confrontational, guilt-presuming approach significantly increases the rate of false confessions, particularly among juveniles and people with intellectual disabilities.

Investigative Reasoning

Cognitive Bias: A systematic pattern of deviation from rationality in judgment, including confirmation bias, anchoring, availability bias, and tunnel vision. Cognitive bias is a documented cause of investigative failure — investigators lock onto a theory early, seek confirming evidence, and discount disconfirming evidence. Structured methodologies exist partly to counter these biases.
Deductive Reasoning: Reasoning from general principles or established facts to specific conclusions. In investigation, deduction applies known rules (e.g. 'a body cannot be in two places at once') to the evidence at hand to eliminate impossible scenarios. Detective fiction popularized deduction, but real investigation relies heavily on the complementary inductive reasoning that builds general conclusions from specific observations.
Occam's Razor: The problem-solving principle that, among competing explanations, the one requiring the fewest assumptions is most likely to be correct. In investigation, Occam's Razor counsels against constructing elaborate theories when a simpler explanation fits the evidence. The principle is heuristic, not a law — the simplest explanation is not always right, but history shows investigators frequently err in the opposite direction by overcomplicating.

Marketing & Retail Science

Eye-Tracking: Technology that measures where and how long a person's gaze rests on elements of a display, shelf, or screen. Eye-tracking studies have generated the evidence behind shelf placement (eye-level is buy-level), heatmaps of retail aisles, and the optimal positioning of call-to-action buttons. The data is granular enough to dictate placement to the inch.
End Cap: The display space at the end of a store aisle, which receives significantly higher foot traffic than mid-aisle shelves. End caps are among the most valuable real estate in retail and are reserved for high-margin items, promotional pushes, or vendor-paid placements. Their effectiveness is one of the most consistently measured variables in store layout design.
Sensory Marketing: Marketing that engages the senses beyond sight — scent, sound, touch, and even temperature — to influence mood, dwell time, and purchasing behavior. The signature scent of a hotel chain, the curated playlist tempo of a retailer, and the ambient lighting of a restaurant are all calibrated using research into how sensory inputs shift consumer behavior measurably.

Media & Narrative Construction

A/B Testing: A controlled experiment in which two versions (A and B) of a headline, image, or layout are shown to different audience segments to measure which performs better on a target metric, typically click-through rate. A/B testing has generated an enormous evidence base about what captures attention, but it optimizes for engagement rather than accuracy — a tension at the heart of modern headline construction.
Click-Through Rate (CTR): The ratio of users who click on a specific link to the number of total users who view a page, headline, or advertisement. CTR is the primary currency of digital media optimization. Because CTR is trivially measurable, it has become the dominant metric driving editorial decisions — often at the expense of depth, accuracy, and context.
Framing Effect: A cognitive bias in which the way information is presented (the 'frame') significantly influences how it is understood and acted upon, even when the underlying facts are identical. A headline framed around survival rates versus mortality rates produces measurably different reader reactions, a fact not lost on headline writers optimizing for engagement.

Prison & Corrections

Contraband: Items prohibited within a prison facility, including weapons, drugs, cell phones, and tools that could aid an escape. Contraband smuggling is a persistent security challenge and a common enabler of prison escapes — nearly every major break involves contraband tools, communication devices, or altered materials smuggled inside.
Security Classification: The system of categorizing prisoners by risk level (minimum, medium, maximum, supermax) to determine housing, privileges, and supervision. Classification errors — placing a high-risk inmate in a lower-security facility — are a recurring factor in prison escapes and institutional violence.
Cell Extraction: The procedure of forcibly removing an inmate from a cell, typically conducted by a trained tactical team using shields, restraints, and sometimes chemical agents. Cell extractions are used when an inmate refuses to comply, barricades the door, or poses an immediate threat.

Private & Corporate Investigation

Skip Tracing: The process of locating a person who has gone missing, skipped out on a debt, or is deliberately evading contact. Skip tracers — private investigators and specialized firms — use database searches, public records, social media, and sometimes pretext to locate subjects. It is a core private investigation skill with no direct law-enforcement equivalent.
Due Diligence (Corporate): The investigation a buyer, investor, or partner undertakes before a business transaction to verify financials, legal exposure, operations, and reputation. Corporate due diligence investigations range from document review to background checks, asset tracing, and surveillance, and are the private-sector equivalent of a pre-trial investigation.
Pretexting: The practice of obtaining information by creating a false pretext — pretending to be someone else or representing a false purpose. Pretexting is regulated differently across jurisdictions; it is restricted in financial contexts by the Gramm-Leach-Bliley Act but remains a tool in some private investigations. Its ethical and legal boundaries are a persistent source of debate.

Product & Technology Failures

Minimum Viable Product (MVP): The simplest version of a product that can be released to gather validated learning about customers with the least effort. The MVP concept was popularized by lean startup methodology. When it fails, it is often because teams ship a product so stripped-down that it tests no real hypothesis, or so overbuilt that it bypasses the learning phase entirely.
Market Cannibalization: The phenomenon in which a new product eats into the sales of a company's existing product rather than capturing new market share. Cannibalization risk is a common reason product launches fail internally — companies delay or weaken new offerings to protect legacy revenue, leaving room for competitors to capture the new category first.
Sunk Cost Fallacy: The tendency to continue investing resources into a failing project because of prior investments already made, rather than evaluating the project on its future expected value. The fallacy is a major driver of product failure — companies ship flawed products because they have already spent millions, even when evidence shows the market has rejected the concept.

Toxicology

GC-MS (Gas Chromatography-Mass Spectrometry): An analytical technique that separates and identifies the chemical components of a sample. Gas chromatography separates the mixture into individual compounds, and mass spectrometry identifies each compound by its molecular weight. GC-MS is the gold standard in forensic toxicology for detecting drugs, poisons, and their metabolites in blood, urine, and tissue samples, and is also used in arson investigation to identify accelerants.

Trace Evidence

Latent Fingerprint: A fingerprint left on a surface by the natural oils and sweat present on friction ridges of the skin, invisible to the naked eye. Latent prints are developed using powders, chemical fumes (such as cyanoacrylate/superglue), or alternate light sources. Once developed and photographed, they are compared against known prints using the ACE-V methodology (Analysis, Comparison, Evaluation, Verification).
Luminol: A chemical reagent that reacts with the iron in hemoglobin to produce a blue luminescence visible in darkness. Luminol can detect blood traces even after surfaces have been cleaned, making it invaluable for revealing bloodstain patterns at crime scenes. However, it also reacts with bleach, copper, and certain plant enzymes, producing false positives, and the reaction can consume small DNA samples.