Crime Scene Search Methods and Evidence Recognition

An organized examination of a crime scene using a planned method to locate, recognize, and document potential evidence.

To achieve appropriate coverage of the relevant area while reducing missed evidence, unnecessary disturbance, and duplicated effort.

A search in which investigators move along parallel lines across a designated area to examine it systematically.

A search using two sets of approximately perpendicular parallel paths to examine an area from different directions.

A search in which an investigator follows a spiral path moving inward or outward from a selected point.

A method dividing a scene into manageable sections that are searched separately and systematically.

A search in which investigators move along radial paths between a central point and the outer boundary of the search area.

A strip or grid search may be appropriate, depending on the scene, available personnel, and evidence characteristics.

A zone search, with individual rooms or areas treated as separate search sections.

Coverage may be uneven, particularly in spaces between radial paths farther from the central point.

The identification of materials or conditions that may have investigative or forensic significance.

Patent evidence is readily visible; latent evidence is not readily visible and may require suitable examination or development methods.

Evidence that may be easily altered, lost, degraded, or destroyed by environmental conditions or handling.

Evidence that changes or disappears relatively quickly, such as an odor, temperature condition, or temporary environmental observation.

To document or preserve relevant conditions before they disappear or materially change.

To coordinate recovery in a manner that protects fragile material, reduces contamination, and preserves relevant relationships.

To identify the location of an item for documentation and organized scene processing.

To preserve a record of the original visible condition without markers introduced by investigators.

To provide a reference for the item's apparent size while documenting its visible characteristics.

Unscaled photographs document the item's appearance without added objects; scaled photographs provide size reference.

Orientation photographs establish location and context; identification photographs emphasize the characteristics of a particular item.

To document positions in a way that can be checked and reconstructed later.

A method locating objects by measurements taken along and perpendicular to a selected reference line.

A method locating an object by measuring its distance from two established reference points.

A method locating evidence using perpendicular distances from two established reference lines or surfaces.

To represent measured distances and spatial relationships using a consistent proportional scale.

A unique reference assigned to an evidence item to support accurate documentation, tracking, and retrieval.

A unique identifier, item description, collection location, collector's identity, date and time, and other information required by applicable procedures.

To make unauthorized opening or alteration of an evidence package more readily detectable.

Improper packaging can cause deterioration, leakage, contamination, breakage, or loss of forensic value.

Trapped moisture may promote microbial growth and degradation of biological evidence.

Follow laboratory-approved procedures for prompt drying or suitable temporary storage, using protective measures that minimize contamination and degradation.

To reduce the risk of cross-contamination and preserve the ability to associate material with its source.

To reduce unintended transfer of biological or trace material between items.

To reduce contamination and prevent misleading transfers between samples.

A sample collected for comparison or to evaluate background material, collection conditions, or possible contamination.

A sample obtained from an identified source for comparison with questioned material.

Material whose source, identity, composition, or relationship to an event is being examined.

To help determine whether the surface or material supporting a questioned stain or trace contributes background substances affecting examination.

To assess whether collection materials or procedures introduced contamination into a sample.

To retain microscopic or visible characteristics that may assist qualified examiners in evaluating how the marks were produced.

Doing so may alter the mark, introduce new damage, or compromise later forensic examination.

To prevent deformation, abrasion, or contamination of potentially useful surface details.

A reference sample from a person or source whose material may be legitimately present, used to help interpret questioned evidence.

To document the scene examination, methods used, items collected, relevant observations, and handling of evidence.

Reconstruction evaluates evidence to infer events; reenactment physically demonstrates a proposed sequence, which may or may not accurately represent what occurred.

Because incomplete evidence, alternative explanations, and uncertain assumptions may affect the reliability of inferred events.

Avoid conditions that promote biological degradation or cross-contamination and follow appropriate laboratory-approved drying and packaging procedures.

Cross-contamination that could create misleading associations between evidence items.

Promptly document and protect the impression and use an appropriate authorized recovery method before environmental damage occurs.