What technique involves using sterile swabs to collect both wet and dried blood?

The correct answer pertains to the systematic procedure of collecting blood evidence from crime scenes. This technique involves using sterile swabs, which are specifically designed to avoid contamination, to gather both wet and dried blood samples. The collection of blood evidence is crucial in forensic investigations as it allows for the preservation of biological materials that can provide significant information, such as DNA analysis.

The methodology ensures that the integrity of the blood sample is maintained during the collection process. Proper collection is essential for later analysis and can greatly impact the outcome of forensic examinations. By effectively utilizing sterile swabs, law enforcement officers ensure that the evidence remains viable for forensic testing.

In contrast, the other options refer to different aspects of evidence handling or analysis. Presumptive testing relates to preliminary tests that indicate the presence of substances but do not actually involve the collection of evidence itself. Evidence collection is a broader term that encompasses various types of evidence and does not specifically indicate the technique used for blood. Sample recovery pertains to retrieving samples but lacks the specific detail of using swabs for blood. Therefore, the emphasis on blood evidence collection through the use of sterile swabs defines why this answer is the most precise in the context of the question.