A search plan divides a relevant area into work that can be tracked and reviewed. Strip, grid, spiral, zone, radial and point-to-point approaches describe movement; none guarantees recovery of every item.
Choose and revise the approach for the target, terrain, visibility, personnel and preservation risks. Document searched areas, gaps and finds, and use specialist procedures for hazardous or underwater work.
By the end of this topic you will be able to:
- Compare movement patterns and their coverage limits.
- Choose a search plan for actual targets and conditions.
- Record gaps and reassess the strategy.
- Search pattern
- A documented coverage strategy, with its searched areas and limitations.
- Centrifugal spiral
- An outward-moving spiral; suitability depends on access and preservation risks.
- Centripetal spiral
- An inward-moving spiral; no universal weather rule determines preference.
- Zone overlap
- An explicit assignment of shared boundaries and overlap to prevent gaps.
- Wedge problem
- The widening uncovered space between separated radial paths.
Crime Scene Search Patterns: Purpose and Limitations
Plan coverage before disturbing relevant material, while allowing urgent preservation. Missed evidence can result from coverage gaps, recognition, visibility, collection or later loss; no unsourced ranking identifies a universal main cause.
The Six Patterns
Strip (Lane) Search
Strip searches use adjacent lanes with suitable overlap. Set lane width from target size, visibility, terrain and searcher capability rather than a fixed distance or team size.
- Best for: open outdoor scenes, single or paired searchers, medium-density evidence.
- Misses: evidence near pattern edges if lane overlap is too thin.
Grid (Double Strip) Search
A grid adds passes in another direction and may reveal features hidden on the first pass. It requires additional work, but no universal 50-square-metre threshold or guaranteed doubling of time applies.
- Useful where a second viewing direction improves the search.
- Can still miss concealed, inaccessible or unrecognised material.
Spiral Search
A spiral can begin at the centre or boundary. Choose direction and spacing according to access, actual material at risk and achievable coverage; weather does not establish a universal preference.
Underwater search requires trained public-safety divers and a site-specific safety plan. Visibility, current, tethering, obstacles and reference stability govern the method; do not apply a blanket outward-spiral rule.
- Best for: scenes with a clear central focus (body, blast point), single searcher, small to medium areas.
- Misses: edges of irregular-shaped scenes; spiral assumes a roughly circular area.
Zone (Quadrant) Search
Zones assign responsibility to defined areas and can support parallel work indoors or outdoors. Explicitly assign boundaries and shared features so neither team assumes the other searched them.
- Best for: indoor scenes, large outdoor scenes with multiple teams, scenes with structural divisions.
- Misses: zone boundaries when overlap isn't enforced.
Wheel (Ray) Search
Separated radial paths can leave widening gaps. Assess actual searched swaths rather than assume that a spiral or zone label alone eliminates gaps.
- Best for: small areas and demonstrations.
- Misses: the widening wedges between spokes.
Point-to-Point (Line) Search
Point-to-point examination follows visible material or leads. It does not demonstrate coverage between those points; combine it with an area plan where wider evidence may be relevant.
- Best for: scattered outdoor evidence on irregular terrain, follow-up searches after a primary pattern, evidence trails.
- Misses: evidence between visible items.
Choosing the Right Pattern
The decision tree below consolidates the selection criteria.
Comparing Strip, Grid, Spiral, Zone and Wheel Search Patterns
Scroll horizontally if needed to see the full table.
The pattern is picked during evaluation. Before you can search, you must have done the work in Introduction to Crime Scenes. Once a pattern is running, every found item is documented per Securing and Documenting the Crime Scene and collected per Processing Physical Evidence at the Scene.
Coverage and recognition both matter. Touch DNA cannot be identified by looking at a smudge. Record search conditions and limitations rather than claim an expert eye makes a poorly covered area complete.
Check Your Understanding
Sources
- 1.Crime Scene Investigation: A Guide for Law Enforcement · National Institute of Justice
- 2.Incident scene examination · Forensic Science Regulator, England and Wales