Answer: Avoid cross-contamination of evidence.
In an investigation scene, evidence collection must follow some set of strict guidelines so as to avoid mix up or mistakes. This is to ensure a smooth and quick investigation.
Cross contamination can happen when some other fibers are mistakenly added to the fibres involved in the investigation. This can be avoided by careful selection of only the fibres at the investigation scene and following all standard procedures involved in the the collection of evidence.
