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Evidence Search Pattern Selector

Run the Search Pattern Selector Fullscreen

About This MicroSim

When investigators search a crime scene, they do not wander around looking for clues — they follow a systematic search pattern so that every part of the scene is covered and nothing is missed, double-searched, or trampled. The right pattern depends on the scene: a small room, a measurable outdoor field, and a sprawling outdoor area each call for a different approach, and each choice trades off coverage, time, and the number of searchers you need.

This MicroSim turns that decision into a select-and-run tool. You select a search pattern — Grid/Line, Spiral Inward, Spiral Outward, or Zone/Quadrant — choose a scene type and team size, and press Start Search. Animated searcher dots sweep an overhead grid: cells go from gray (unsearched) to yellow (being searched right now) to green (searched). A live fit rating tells you whether your pattern suits the scene, a warning appears when you assign more searchers than the pattern uses well, and a summary at the end reports how many cells were covered, how many steps it took, and an overall efficiency rating.

How to Use It

  1. Pick a Pattern from the first dropdown (start with Grid).
  2. Pick a Scene from the second dropdown — an indoor room, an outdoor field, or a large outdoor area. The grid resizes to match the scene.
  3. Read the fit rating in the right-hand panel: green (good fit), amber (workable but not ideal), or red (poor fit) for the pattern-and-scene pair.
  4. Set the number of Searchers (1–6) and the animation Speed with the sliders. If you assign too many searchers for the pattern, a warning appears.
  5. Press Start Search to run the sweep; press it again to Pause or Resume. Watch cells turn yellow then green as coverage builds.
  6. When the search finishes, read the summary: cells searched, steps elapsed, and the efficiency rating. Then click any green cell to reveal the kind of evidence that might have been found there.
  7. Press Reset (or change any setting) to clear the scene and try a different combination.

What You Can Learn

  • Select an appropriate search pattern for a given scene type and size, and see immediately whether your choice fits.
  • Compare patterns on the real trade-offs: a grid is the most thorough single-team method for a measurable rectangle; a spiral suits a small scene with one searcher or a single central focal point; zones let a large scene be covered in parallel by several teams.
  • Recognize that more searchers is not always better — crowding a single spiral or line path wastes people and raises the risk of stepping on evidence.
  • Understand why a systematic pattern beats a random search: overlap and full coverage are what keep small items (a fiber, a latent print, a spent cartridge) from being missed.

You can embed this MicroSim on your own web page with this iframe:

<iframe src="https://dmccreary.github.io/forensic-science/sims/search-pattern-selector/main.html"
        width="100%" height="602" scrolling="no"></iframe>

Lesson Plan

Audience: High-school forensic science (grades 9–12) Time: 15–20 minutes Bloom level: Apply (L3) — select the appropriate search pattern for a given scene.

Predict-then-run (the core routine). For each scene, students first state which pattern they would choose and why, then select it and press Start Search to test their reasoning against the fit rating and the efficiency summary. The prediction step is what pushes this activity from "watch dots move" to applying a selection rule. Have students run the same scene with two different patterns and compare the step counts.

Guided questions:

  • Set the scene to Large outdoor area and try the Spiral Inward pattern. Why does the fit rating warn against it, and which pattern does the panel recommend instead?
  • Choose the Spiral Inward pattern, then drag the Searchers slider to 6. Read the warning. In plain language, why does crowding one spiral path waste searchers?
  • Run an Indoor room with the Grid pattern at one searcher, then at two. How does the number of steps change, and what does that tell you about the coverage-versus-time trade-off?

Extension. Real scenes are rarely a clean rectangle. Ask students to describe a scene the sim does not model — a winding hiking trail, a multi-room apartment, a vehicle interior — and argue which pattern (or combination) they would choose and what they would give up. Note honestly that no pattern guarantees finding everything: search effectiveness also depends on lighting, searcher training, and how well the scene was secured first.

References

Specification

This MicroSim was generated from a specification in Chapter 2: Crime Scene Investigation and Evidence Collection.

Design note: the specification asked for a control panel along the right ~30% that itself held "animated searcher dots." To keep the Apply (L3) objective in focus — selecting the right pattern — the right panel was used for the decision feedback (pattern description, live fit rating, scene recommendation, searcher warning, and the coverage summary) while the animated searcher dots run on the overhead grid where their coverage is actually visible. The spec's optional "contamination mode" (red skipped cells) was omitted because every pattern in this build provides complete coverage, so there are no skipped cells to flag; the more instructive risk — assigning too many searchers to a single path — is surfaced as a live warning instead. The click-to-reveal-evidence behavior is preserved on searched (green) cells.