Forensic Evidence Collection and Chain of Custody

A garment, swab, or blood tube is not useful evidence simply because it contains biological material. Its identity, condition, and history must remain credible from the moment it is collected. The chain of custody is the contemporaneous record of that history: what was collected, when and by whom, how it was secured, and every person who later received it. This record protects the evidentiary value of DNA, body-fluid, or trace material. A technically accurate laboratory result can still be questioned if no one can show who handled the item or whether the package was altered. A gap does not automatically make evidence unusable, but an unexplained gap can undermine its reliability and may be challenged in legal proceedings. The nurse is not responsible for deciding whether the evidence proves an offence. The nurse is responsible for preserving the item, preventing contamination, identifying it accurately, and making its movement traceable.