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The six crime scene search patterns with diagrams, what each is good for, what it misses, and the call most SOCOs get wrong about spiral search.
A crime scene search is the systematic, pattern-based examination of a defined area to locate physical evidence. There are six canonical patterns: strip, grid, spiral, zone, wheel, and point-to-point. The right pattern depends on the size and shape of the scene, the number of searchers available, and whether the scene is indoor or outdoor. Picking the wrong pattern doesn't fail the search. It just misses evidence.
Here's the thing about search patterns: they're the most diagram-heavy topic in Module 1, and the exam loves them precisely because the answer fits on a page and either looks right or doesn't. Memorise the shapes first, the trade-offs second, and the edge cases third. We'll do all three below.
A pattern is only as good as the searcher's eye.
The pattern is chosen during the evaluation phase, before any evidence is collected. What it isn't: a guarantee of finding everything. A pattern is only as good as the searcher's recognition skill, and most missed evidence is missed because the searcher walked over it, not because the pattern was wrong. Worth holding onto that as you read through the six options.
Strip, grid, spiral, zone, wheel, point-to-point.
The strip method is the default for any open outdoor scene with one or two searchers. Lane width should match the searcher's eyeline, typically 1 to 1.5 metres for ground-level evidence, narrower if the search is for trace material. The strip method gets criticised for missing evidence that falls between lanes; the fix is overlap, not a different pattern.
A decision tree that fits on an answer sheet.
This is what gets asked in interviews and on the second half of long-form questions. Commit the tree to memory.
Six patterns, one table.
| Pattern | Best for | Searchers | Main weakness |
|---|---|---|---|
| Strip / Lane | Open outdoor scene, regular shape | 1–2 | Misses near lane edges if overlap is thin |
| Grid | Thorough outdoor search, high-stakes case | 1–3 | Doubles the time of strip search |
| Spiral | Central-focus scene (body, blast point) | 1 | Assumes near-circular area; struggles on irregular shapes |
| Zone / Quadrant | Indoor scenes, multi-team work | 2–4+ | Zone-boundary evidence missed without overlap |
| Wheel / Ray | Demonstrations, very small areas | 1 | Widening wedges between spokes; rarely used in field |
| Point-to-point |
A homicide is reported in a 4 BHK flat. The body is in the master bedroom, a struggle has clearly occurred in the corridor, and a kitchen knife is missing. With a four-person SOCO team available, what is the best search pattern to deploy?
Grid search is the gold standard when you have time. It catches what strip misses, particularly small or light-coloured trace evidence whose visibility depends on the angle the searcher is looking from. The cost is double the time. For NFSU mock exercises, you'd default to grid for any homicide scene over 50 square metres.
Spiral search is where most candidates get one detail wrong. The two directions, outward (centrifugal) from the body or inward (centripetal) from the perimeter, sound symmetric but are not. Outward spiral risks contaminating the most evidence-dense area first; inward spiral risks losing evidence at the perimeter to weather or bystanders while the searcher is still working through the outer rings. The teaching answer is that outdoor scenes with intact perimeters prefer outward; outdoor scenes with weather risk prefer inward.
Zone search is what you use indoors. Each room is a zone, sometimes each functional area within a room (kitchen counter, kitchen floor, dining surface). The big advantage is parallel work; the big risk is that evidence on a zone boundary gets missed by both teams who assumed the other was handling it. The fix is an explicit overlap protocol.
Wheel search is in the syllabus because it's in the syllabus, not because anyone uses it. The wedge problem is fundamental: as searchers move outward, the unsearched gap between spokes widens with distance. Spiral or zone is almost always a better call. You'll still be tested on it, though.
Point-to-point is the pattern of last resort. It's used for outdoor scenes with weird shapes like a hillside, a river bank, or a road shoulder, where a regular pattern would leave huge wasted area but where evidence is visible enough to chain from one waypoint to the next. The blind spot is everything that isn't on the chain.
| Irregular terrain, visible scattered evidence |
| 1–2 |
| Misses everything off the chain |
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.