Securing and Documenting the Crime Scene

Assess threats and medical needs first. Set and revise boundaries to protect relevant material and permit necessary access; a newly recognised evidence area can require expansion.

Access arrangements should be recorded and understood by everyone working at the scene.

• Use suitable barriers and a controlled route that avoids vulnerable material.
• Record boundaries, access routes and subsequent changes.
• Expand or revise the cordon when new information requires it.
• Document any release of an area and the responsible decision.

Protection, access control and documentation often occur in parallel through different personnel. Avoid a fixed sequence that delays necessary aid.

Record actual entrants and movements, including personnel who arrived before formal control. Assign and document responsibility for maintaining and handing over the log.

Use recording methods that answer the question and preserve context. Notes, sketches, photographs and video can cross-check one another.

A discrepancy requires investigation. Another recording channel does not automatically repair a missing measurement or prove that the disputed account is true.

Keep a contemporaneous record of observations, decisions, actions and supplied information. Identify the recorder, exhibit references and relevant times; distinguish direct observation from another person’s account.

What every entry must contain:

• Time and date of the entry, to the minute.
• Weather and lighting at the time, especially for outdoor scenes.
• Names and designations of everyone inside the inner cordon at that moment.
• Action taken and the reason.
• State of evidence before and after any action.

Format rules that the defence routinely tests at trial:

• Use the approved paper or electronic recording system.
• Preserve the original entry and make corrections traceable.
• Identify delayed entries and their basis.
• Retain linked pages, files and versions; do not silently replace a record.

Paper ink is not immune to alteration, and a well-controlled electronic record is not inherently inferior. Follow the applicable retention, access and audit procedures.

An initial sketch and later presentation serve different purposes. Required formats depend on the service and task; retain the measured field record and identify how a later drawing was produced.

Rough Crime Scene Sketches: Measurements and Field Notes

Drawn on the scene as documentation runs in parallel. The rules:

• Freehand. Not to scale. Compass direction marked anyway.
• All measurements written directly on the sketch in pen.
• Every evidence item gets a number, keyed to the notes and the photographs.
• The sketch shows the cordon boundaries and the common approach path.
• Signed and dated by the SOCO before leaving the scene.

Finished Crime Scene Sketches: Scale and Presentation

Select a usable scale for the drawing and medium, or mark it clearly as not to scale. Preserve orientation, reference points, measurements and item identifiers.

• A scale bar.
• A north-pointing compass arrow.
• A legend listing every numbered item.
• A title block with case number, date, location, sketcher's name and verifying officer's signature.
• No editorial additions. The finished sketch must agree with the rough sketch on every measurement; new "interpretations" are not added.

Crime Scene Measurement Methods for Sketching

Select measurement methods according to geometry, reference stability, access and required accuracy.

• Triangulation: measure from two identified fixed points and record the baseline geometry and side to remove mirror ambiguity.
• Baseline offsets: record distance along a fixed baseline and perpendicular offset, with origin and side.
• Polar coordinates: record distance and angle from a fixed origin and defined reference direction.

Road scenes can suit a baseline, total-station survey or another method. Triangulation does not require equidistant reference points; the available geometry and accuracy determine suitability.

In India, BNSS section 105 addresses audio-video recording within its specified search-and-seizure scope and forwarding to a specified magistrate. Read actual state procedures; it is not a worldwide duty to make an uninterrupted scene film.

• Assign recording, storage and forwarding responsibilities under the applicable procedure.
• Preserve original files and document interruptions or later derivatives.
• Record integrity checks where used; a matching hash does not prove the recorded events or all earlier provenance.

This sits alongside the four-stage processing pipeline we covered in Introduction to Crime Scenes, and feeds directly into Chain of Custody once the recording is sealed.

Review consistency and completeness before finalising the record. Do not assume every difference has the same legal or scientific significance.

• Compare clocks, time zones and event definitions before reconciling timestamps.
• Explain missing access records and corrections transparently.
• Investigate spatial differences against the original measurements and stated accuracy.
• Retain original and derived records with their provenance.

Assess how the discrepancy affects the interpretation. Its significance depends on its cause and the questions the evidence addresses.