What is the recommended way to preserve blood evidence?

Preserving blood evidence properly is crucial for forensic analysis and maintaining the integrity of the evidence. Collecting blood in a paper bag is the recommended method because paper allows for air circulation, which is important to prevent the growth of mold and degradation of the sample. Paper bags are absorbent and can help in managing any excess moisture, thereby maintaining the quality of the blood sample over time.

Moreover, using a paper bag minimizes the risk of chemical reactions that may occur with certain plastics and helps in avoiding contamination from external sources. Glass containers, while they can preserve evidence well, pose a risk of breakage and can be difficult to seal tightly without introducing contamination. Plastic bags are not suitable as they can trap moisture and promote bacterial growth, while cardboard boxes do not provide the same level of protection or moisture control as paper bags. Thus, using a paper bag is the most effective method for preserving blood evidence in a way that supports future analysis.