When collecting blood evidence, why is it important to use sterile swabs?

Using sterile swabs to collect blood evidence is essential primarily because it prevents contamination. Contamination during the collection process can introduce foreign substances into the sample, which can compromise the integrity of the evidence and potentially alter the results of any subsequent analyses. Blood samples are particularly sensitive, and even tiny amounts of external material—such as bacteria, viruses, or other biological matter—can affect forensic testing outcomes.

Maintaining the cleanliness of the collection tools ensures that only the blood sample being tested is present, allowing for a more accurate representation of the evidence as it relates to the investigation. Forensic laboratories require uncontaminated samples to draw valid conclusions, making the use of sterile equipment a critical step in the evidence collection process.