Search, Collection, Packaging and Preservation

A systematic search pattern ensures that the scene is covered in a planned sequence, reducing the chance of items being missed or stepped on before they are found. The pattern is chosen before any search begins, based on the scene's physical characteristics.

In practice, most indoor scenes default to a zone or strip method adapted to the room layout. Outdoor scenes, particularly in cases of missing persons or body searches, rely on strip or grid patterns with GPS tracking to log coverage. The spiral is more common in structured forensic textbooks than in large-scale fieldwork, where maintaining equidistant spacing over rough terrain is impractical.

Before anything is collected, it must be documented: photographed (all three levels), noted, and sketched into position. Collection is always the last action before packaging. Once this prerequisite is confirmed, the core collection principles apply:

• One item at a time. Never handle two items simultaneously. Each receives individual attention, documentation, and packaging before the next is touched. This prevents inadvertent cross-transfer between exhibits.
• Clean tool per item. Forceps, swabs, spatulas, and cutting tools must be clean (not merely wiped) before touching each new item. Re-using a swab that picked up blood from one surface on a second surface contaminates both and invalidates both results.
• Change gloves between items. Gloves acquire trace from every surface touched. Changing between items prevents transfer from exhibit to exhibit via the examiner's hands.
• Handle by edges and non-evidentiary surfaces. A knife is picked up by the tip of the blade, not the handle where fingerprints and DNA are deposited. A document is held by its corners. The principle is: touch where evidence is least likely to be.
• Collect reference samples alongside evidence. A soil sample from under a body needs a control sample from a comparable area away from the body, so the laboratory can distinguish the soil that was there from what was deposited. DNA from the victim, blood standards, control swabs from surfaces not in the event area: these reference samples make comparisons possible.

Biological evidence, including bloodstained clothing, swabs, hair roots, and tissue, contains water. Bacteria are present on virtually every biological surface. Seal that evidence in a plastic bag and you create a warm, anaerobic, moist environment that is close to ideal for bacterial growth. Within hours, the bacteria begin degrading the proteins and nucleic acids that the laboratory needs. In poor packaging conditions, bacterial activity begins degrading DNA within hours, and under extreme heat and moisture, a blood sample may yield a severely compromised or unusable profile within days.

The solution is consistent: biological evidence goes in breathable containers. Paper bags are the standard. For wet exhibits (clothing soaked in blood, swabs not yet dried), there is a mandatory intermediate step: the item must be air-dried before final sealing. A drying room with controlled airflow and no cross-contamination risk is used for large items. Swabs are left in their collection tube with the cap loosely on, or dried in a swab box, before the cap is sealed.

• Bloodstained clothing: air-dry fully, then fold so stained areas do not contact each other, then wrap in paper or package in a paper bag.
• Swabs from biological stains: dry in a swab drying box or under a clean airflow, then seal in the collection tube. Never seal a wet swab.
• Hair with roots: dry bindle wrap in paper. Roots contain nuclear DNA; protect them from moisture and physical abrasion.
• Reference blood standards from living persons (suspect or victim samples): collected directly into specialist tubes (EDTA vacutainers for whole blood) designed to preserve DNA, then refrigerated, not frozen.

Packaging is not just protection; it is part of the evidential record. A well-packaged exhibit can be shown in court exactly as it was sealed at the scene. Damage, degradation, or a broken seal that occurred in transit can render an otherwise solid piece of evidence inadmissible or heavily discounted. The correct packaging choice depends on the evidence type, size, and fragility.

1. Bindle wrap (trace evidence)
   Used for fibres, hairs, powder, glass fragments, and any small, fine material. A sheet of clean white paper is folded with all four edges tucked in, creating a sealed inner pocket. No staples or tape touch the evidence space. The bindle goes inside a labelled outer envelope. Trace evidence is too fine to secure in a bag without loss and contamination.
2. Paper bag or paper envelope
   Standard for any biological item once dried: clothing, shoes, fabric, bedding, hair. Size is matched to the item so there is no excess space (excess space allows items to shift and shed). The top is folded over and sealed with tamper-evident tape, not stapled through the evidence space.
3. Sealed plastic bag
   Appropriate for inorganic items: a bullet, a knife (cleared of biological material for immediate transport), glass fragments, a tool, a mobile phone. For electronic devices, specialist anti-static bags or Faraday bags are used to prevent signal reception and remote wiping.
4. Rigid container (box, tube, vial)
   Fragile items, sharp objects, or items that must not be compressed: a bloodied screwdriver where the tip must not be bent, a fragile glass exhibit, a swab in its collection tube. Rigid containers prevent physical damage that could be confused with damage from the offence itself.

Every exhibit must be labelled at the moment of packaging, before it leaves the inner cordon. Labelling later, from memory, introduces the possibility of mix-up that no court will accept without reservation. The label must appear on the packaging itself, not on a loose tag that can fall off.

• Exhibit reference number: unique to this item in this case. Typically formatted as the officer's initials plus a sequential number (e.g., JT/01, JT/02).
• Case number: the investigation reference that connects the exhibit to the case file.
• Description: what the item is, briefly. 'Blue cotton sock, bloodstained' rather than 'evidence item'.
• Exact location found: room, specific position. 'Under the kitchen sink, behind the pipe' is useful; 'kitchen' alone is not.
• Date and time of collection.
• Collector's name and signature: the person who physically recovered the item takes legal responsibility for its condition at collection.

The exhibit log is a master document that lists every item recovered from the scene in order of collection. It shows the exhibit number, description, location, time, collector, and where the item went next. This log is the backbone of the chain-of-custody record and must be updated each time an exhibit changes hands.