What is the recommended method for recovering blood evidence?

The recommended method for recovering blood evidence is to allow it to air dry before packaging it in clean paper bags. This approach is crucial because it helps preserve the integrity of the biological evidence. Air drying minimizes the risk of contamination, degradation, or the growth of mold and bacteria, which can occur if the blood is packaged while still wet or stored in a non-breathable container.

Using clean paper bags is preferable because they allow for airflow, which helps in preventing moisture retention that could compromise the sample. Additionally, paper packaging is ideal for biological materials, as it absorbs moisture and does not promote a sealed environment that could lead to spoilage.

Other methods, such as wiping the evidence immediately or using heat and sealing techniques, might damage or alter the evidence, making it less useful for forensic analysis. Storing blood evidence in liquid form is generally not advisable, as it can lead to significant contamination and the potential loss of critical forensic information. Thus, the method of allowing blood evidence to air dry and then packaging it in clean paper bags is the best practice for preserving its forensic value.