Chain of Custody (Digital)
Definition
The documented record of who created, processed, stored, and accessed a digital file from its acquisition to its presentation in court. For spatial data, this includes file checksums, processing logs, and version-controlled storage.
- Core elements
- Creation, processing, storage, and access records
- Integrity check
- File checksums (hash values)
- Applies here to
- Spatial/GIS data used in search management
- Storage requirement
- Version-controlled storage
Common questions
Why do checksums matter more for digital than physical custody?+
A digital file can be copied or altered without leaving physical traces, so a checksum computed at collection and re-verified at each stage is the primary way to prove the file presented in court is bit-for-bit identical to what was collected.
Why does version control matter specifically for GIS data?+
Search-management GIS layers are often updated iteratively as new search areas are covered, so version control preserves the exact state of the data at the time any particular decision or report was made, rather than only the final version.
Related terms
- Coordinate Reference System (CRS)
- The mathematical framework defining how coordinates relate to real-world positions on the Earth's surface. All layers in a forensic GIS must share...
- Georeferencing
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- Route Cost Analysis
- A GIS operation using a friction or cost surface (based on slope, vegetation, and path availability) to model the least-effort path between...
- Search Coverage Layer
- A polygon or raster attribute layer recording which portions of the search area have been surveyed, the method used, and the outcome....
- Weighted Overlay
- A GIS operation that combines multiple raster layers into a single output by multiplying each layer by a weight and summing the...