Snares, Traps, and Cable Evidence

The physical properties of snare wire are the first layer of forensic characterisation. A trained examiner can often place a snare in a rough category immediately: is this domestic fence wire, military communications cable, vehicle brake cable, or purpose-built snare wire imported into the country? Each has a gauge range, a material composition, and a surface treatment that narrows the population it came from.

• Gauge: measured with a micrometer or optical comparator. Common bushmeat snare gauges are 1.6-3.0 mm; heavier wire (3.0-5.0 mm) is associated with large-antelope and big-game snaring. Gauge narrowing from consistent sourcing within a syndicate can link multiple snares to the same supply batch.
• Material: X-ray fluorescence (XRF) spectroscopy identifies metal composition (iron, copper, zinc coating) non-destructively. Optical microscopy shows strand count and twist angle. Telephone cable has a distinctive colour-coded PVC coating over copper strands; its presence signals infrastructure theft as a secondary offence.
• Surface treatment: galvanisation (zinc coating), bright steel, and copper each have different corrosion rates and elemental profiles. Matching the elemental profile of a snare wire to a wire reel found at a suspect's premises is class-level evidence but becomes powerful when combined with gauge match and tool-mark evidence.

When wire cutters close, the cutting-face geometry determines the cut's overall shape (class characteristic), while microscopic nicks and wear on those faces produce striation patterns unique to that tool at that moment of use (individual characteristic). Two cuts made in quick succession by the same cutters will share striation agreement that a different pair cannot replicate.

The examination protocol mirrors the AFTE toolmark standard used for bullets: the examiner looks for sufficient agreement in the individual characteristics of the striations and asks whether the agreement exceeds what would be expected by chance. A positive identification is reported when the examiner finds sufficient agreement in individual striation characteristics and determines that no other tool would produce the same pattern. An inconclusive result is reported when the material quality or the extent of the striation surface does not support a definitive conclusion.

Wire cutters submitted as suspect tools must be test-cut on the same gauge wire as the evidence and under similar cutting conditions (angle, one-cut versus scissor action). The test cuts and the evidence cut ends are examined side by side. Photographs at 10x-40x magnification document the comparison for the court exhibit.

When an animal is killed or recovered alive from a snare, its body carries a record of the wire's interaction with its tissue. A veterinarian or pathologist examining these injuries can characterise the snare type and duration of entrapment, which both assists the forensic case and, for live recovered animals, guides treatment.

• Circumferential groove: the defining mark of a wire snare on a limb or neck. The groove width corresponds to wire gauge. In leg snares, the groove is typically just above the fetlock or ankle joint, where the animal's struggling attempts create a focal constriction point.
• Spiral limb fracture: characteristic of leg snaring in larger animals. As the animal twists to free its leg, the torsional force below the snare produces a spiral (torsional) fracture of the distal long bone. The fracture pattern is distinct from a fall fracture or a gunshot fracture.
• Embedded wire: in animals that have struggled for hours or days, the wire may have cut through skin and become embedded in the subcutaneous tissue or around the periosteum of the bone. Recovery of embedded wire provides the physical snare sample even when the rest of the trap was not found.
• Hair and skin in wire: hairs trapped in the wire strands at the bite point can be examined for species and, from a hair root, for individual DNA. Skin cells deposited on the wire by the animal's struggling can supplement a partial DNA profile.

Snare manufacture involves sustained hand contact: bending, twisting, tying the loop, and cutting to length. Each contact transfers material in both directions. The handler deposits fingerprints on smooth wire surfaces, epithelial cells recoverable as touch DNA, and clothing fibres; the wire deposits metal particles and surface coatings onto the handler's skin and clothing.

Field-recovered snares are exposed to weather by definition, and fingerprint or DNA evidence that would be routine on a dry indoor surface may be absent after a day of rain. This does not eliminate trace evidence as an avenue; it changes the collection priority. Fibres trapped mechanically in wire strands are more persistent than latent fingerprints in wet conditions. Touch DNA in the strand crevices of twisted wire can survive where surface cells are washed away. Collection protocol must account for these differences: swab the wire for DNA before packaging, then package in paper to allow continued drying.

Bushmeat snaring operates at a scale qualitatively different from trophy-species poaching. A single hunting camp in central Africa may set thousands of snares across several hundred square kilometres each season. The animals targeted (antelope, duiker, bush pig, monkey) are hunted primarily for food and for commercial sale in urban markets. The snares are typically small gauge, simple sliding-loop construction, and made from whatever wire is locally available: telecommunications cable stolen from government lines, fence wire from agricultural land, or vehicle brake cable from informal mechanics.

At this scale, individual snare-to-person attribution is rarely practical. The forensic strategy shifts toward supply-chain analysis: can the wire type be traced to a specific source (a stolen cable, a hardware batch, a vehicle workshop)? Can the construction method identify a specific cultural or regional practice? Can GPS and timing data from snare removals build a spatial picture of a specific camp's territory? TRACE Wildlife Forensics and national game authorities in Zambia and Zimbabwe have used wire-source matching to build cases against commercial bushmeat operations by linking the wire in hundreds of snares to a single stolen telecommunications cable batch, establishing the scale of the operation as evidence of commercial rather than subsistence hunting.