IAI CSCSA key terms

A chronological written record showing who collected, handled, transferred, and stored each item of evidence from seizure to courtroom presentation, used to prove the evidence was not altered, substituted, or contaminated.

The forensic premise that every contact between two objects leaves a trace-material transferred from one to the other-so perpetrators both deposit and pick up evidence at a scene.

The initial actions at a scene: securing and preserving life, isolating the area, detaining witnesses, protecting evidence from disturbance, and documenting initial conditions before investigators arrive.

Controlling access to the scene through barriers, posted officers, a perimeter, and an entry log so that only authorized personnel enter and evidence integrity is maintained.

A running record listing every person who enters or leaves the scene, with name, agency, purpose, and times, used to account for all access and support chain-of-custody claims.

The location where the criminal act actually occurred or where the greatest volume of physical evidence is found, as distinct from secondary sites connected to the event.

Any location other than the primary scene where evidence related to the crime exists, such as a vehicle, dump site, or suspect's residence, requiring its own documentation and processing plan.

The initial walk-through in which the lead investigator observes the whole scene, identifies evidence and hazards, and forms a plan for documentation, search, and collection.

A systematic method for covering a scene-such as line, grid, spiral, zone, or wheel-chosen based on terrain, scene size, and evidence type to ensure no area is missed or double-searched.

A search method in which investigators cover an area in parallel lines and then repeat the sweep at right angles, giving two-directional coverage useful on open ground and large surfaces.

A search in which team members move abreast along parallel lanes, used for large outdoor areas with relatively uniform terrain where many searchers are available.

Dividing the scene into labeled sectors and assigning each to a searcher or team, a method suited to confined spaces, cluttered interiors, and complex multi-room scenes.

The combined record of a scene created through notes, photography, videography, sketches, and measurements, intended to preserve conditions and support later reconstruction and testimony.

Photographing the scene in a sequence from overall to midrange to close-up, including scale references and orientation shots, so images accurately show location, condition, and detail without distortion.

A record linking each photograph to its subject, location, direction, camera settings, and sequence number, allowing images to be authenticated and matched to the scene and sketch.

A scale or not-to-scale drawing showing the scene layout, fixed reference points, and measured positions of evidence, used to clarify spatial relationships that photographs alone cannot convey.

A measuring technique that fixes an item's position by recording distances along a straight reference line and the perpendicular offset from that line, producing accurate coordinates on a sketch.

Locating an item by measuring distances from two or more fixed reference points, so the position can be plotted as intersecting arcs on a sketch or diagram.

A permanent, identifiable feature-such as a doorway, utility pole, or building corner-from which evidence positions are measured so the scene can be related to a fixed coordinate system.

The introduction of foreign material or DNA into a sample, or the unintended transfer of evidence between items, which can weaken or destroy its evidentiary value and must be prevented and documented.

Selecting appropriate containers-paper bags for biological items, sealed metal or plastic for arson debris, rigid containers for sharps-and sealing, labeling, and initialing them so contents stay intact and accounted for.

Handling blood, saliva, tissue, and other biological material so it is air-dried, kept out of sunlight and heat, and packaged in breathable containers to prevent degradation of DNA.

Small or microscopic materials such as hair, fibers, glass fragments, paint chips, soil, and gunshot residue that can link people, objects, and locations under the exchange principle.

Material that moved from one surface or person to another during contact, including fingerprints, footwear impressions, bloodstains, and trace materials, whose direction and pattern may indicate sequence of events.

Evidence of unknown origin collected at the scene, later compared against a known or reference sample taken from a suspect, victim, or object to determine whether they share a common source.

A reference specimen collected from an identified source-such as a buccal swab, known fingerprint, or control hair-used as the comparison standard for questioned evidence.

Fingerprints, palm prints, or footwear impressions collected from victims, residents, and responders so their prints can be excluded from those of unknown origin found at the scene.

An invisible fingerprint or palm print deposited by sweat and oils, developed at the scene or on items using powders, chemical reagents, or lighting techniques before being photographed and preserved.

Marks left by a tool, shoe, tire, or other object pressing into or against a surface, documented and cast or photographed so they can be compared with known exemplars.

Interpreting the size, shape, distribution, and directionality of bloodstains to reconstruct events such as impact, cast-off, transfer, or drip patterns at a scene.

Building an evidence-based account of what happened, in what order, and where, by combining scene documentation, physical evidence, wound patterns, and witness statements.

A specialized lamp-ultraviolet, infrared, or specific visible wavelengths-used with filters or goggles to reveal latent prints, biological fluids, fibers, and altered documents not visible under normal lighting.

The condition of evidence being unaltered, unadulterated, and fully accounted for from collection through trial, demonstrated by proper packaging, documentation, and an unbroken custody record.

Entry to a scene without a warrant justified by exigent circumstances such as emergency aid, hot pursuit, or immediate destruction of evidence, later documented and reviewed for legal sufficiency.

Urgent conditions-imminent danger to life, fleeing suspect, or likely destruction of evidence-that permit immediate action without prior judicial authorization, subject to later review.

A large-scale incident with many casualties and dispersed remains, managed through morgue operations, victim identification, grid search, and coordination among multiple agencies.

The investigator's written narrative describing the scene, observations, evidence collected, personnel present, and actions taken, forming the core record for review and courtroom use.

Gloves, masks, coveralls, eye protection, and shoe covers worn to protect personnel from hazards and to prevent the transfer of DNA, trace material, and contaminants into the scene.