IAI CCSI key terms

The chronological, documented record of who collected, handled, transferred, and stored an item of evidence, from seizure to courtroom. Gaps or undocumented transfers can make evidence inadmissible or weaken its weight.

The foundational idea that every contact between a perpetrator and a scene leaves something behind and takes something away. It justifies systematic collection of trace evidence at points of contact.

The initial steps taken by the first officer on scene: securing the area, preserving life, detaining suspects, protecting evidence, and starting a scene log before investigators arrive.

Controlling access to a crime scene through barriers, posted officers, and an access roster so that only authorized personnel enter and contamination or loss of evidence is prevented.

A running written record of every person who enters or leaves a scene, with name, agency, purpose, and time. It supports both contamination defense and later courtroom testimony.

A structured walk-through before collection begins to identify scene boundaries, hazards, evidence locations, and the resources needed, forming the basis of the investigative plan.

A systematic examination of the scene, often from the perimeter inward or in a grid, to locate, document, and prioritize evidence before anything is moved or collected.

A defined route used to cover a scene methodically, such as line, grid, spiral, or zone searches, chosen to suit terrain and evidence type and to avoid missed areas.

Documenting the scene and evidence with overall, midrange, and close-up images, often including scale references, before items are moved, to preserve context and detail for later analysis.

Recording the precise location of each item of evidence relative to fixed reference points, using measurements, sketches, or scans, so positions can be reconstructed accurately later.

Placing each item in an appropriate container, such as paper bags, envelopes, or rigid boxes, sealed and labeled with case details, to prevent loss, cross-transfer, and degradation.

Practices such as wearing gloves and protective clothing, changing gloves between items, using clean tools, and separating items that stop foreign material from entering or altering evidence.

Handling blood, saliva, semen, and tissue so they are not degraded: air-drying wet items, using paper rather than plastic, keeping samples cool, and avoiding heat, sunlight, and moisture.

Small or microscopic material such as hair, fibers, glass, paint, soil, or gunshot residue that can link a person or object to a scene under the exchange principle.

Genetic material recovered from biological stains or cells that can be profiled to identify or exclude a contributor. Collection must protect it from degradation and cross-transfer.

Latent, patent, or plastic prints recovered from surfaces that can identify a person through ridge pattern comparison. Latent prints require powders, chemical reagents, or alternate light sources.

Techniques that make invisible fingerprints visible, including powder dusting, cyanoacrylate fuming, ninhydrin, and alternate light sources, selected according to surface and substrate.

Marks left when one object presses into another, such as footwear, tire, or tool marks. Casts, photographs, or lifts preserve the detail needed for comparison.

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

Firearms, ammunition, cartridge cases, projectiles, and related marks recovered at a scene, documented and packaged to preserve trace material and comparison value.

Data stored on devices or networks, such as phones, computers, and cameras, that may be relevant to a case and must be seized and preserved without altering content.

The assurance that an item has not been altered, substituted, or degraded from collection through analysis and trial, supported by documentation, sealing, and secure storage.

A known reference specimen collected alongside questioned evidence, such as a known print or reference DNA, used to interpret or compare the questioned item.

Reference DNA, prints, or other standards collected from victims, responders, or residents so their profiles can be excluded from evidence results.

Building a reasoned account of what happened from evidence positions, patterns, and physical relationships, used to test witness accounts and support investigative theories.

A written or agreed strategy setting out which items to collect, in what order, with which methods and packaging, based on the scene assessment and case priorities.

Gloves, masks, coveralls, and shoe covers worn at a scene to protect responders from hazards and to prevent transferring DNA, trace material, or contaminants onto evidence.

Identifying risks at a scene such as chemicals, biohazards, structural damage, electricity, or hostile persons before work begins, so controls and protective measures can be put in place.

Ranking evidence and tasks by perishability, probative value, and risk of loss so that the most fragile or significant items are documented and collected first.

Evidence likely to disappear or degrade quickly, such as odors, drying biological fluids, melting impressions, or transient digital data, which must be documented and collected early.

A known specimen from a person, object, or location used for comparison against questioned evidence, such as a buccal swab, known print, or exemplar.

The document accompanying evidence to the laboratory that lists items, requested analyses, case details, and chain-of-custody entries so examiners know what to test and why.

The combined record of a scene through notes, photographs, sketches, and logs that captures conditions and evidence locations before, during, and after collection.

A scaled or not-to-scale drawing showing the scene layout, fixed reference points, and evidence positions, often with measurements, to supplement photographs and notes.

Transfer of material between items, persons, or locations, such as DNA moving from one swab to another, which can create false associations and undermine evidence value.

A tamper-evident closure on a package, initialed and dated by the collector, that shows whether the container has been opened since it was sealed.

The formal handover of a scene back to its owner or occupier after processing, documented with final walk-through, photographs, and a record of what was taken or altered.