Which method is recommended for collecting liquid blood evidence?

The recommended method for collecting liquid blood evidence is to absorb it with a clean white cotton cloth. This technique is essential because it allows for the careful extraction of the blood sample without compromising its integrity. Using a clean absorbent material prevents contamination and ensures that the evidence can be properly analyzed in forensic settings.

Absorbing blood with a cloth is effective in soaking up the liquid while also maintaining the characteristics needed for further testing. The choice of a white cotton cloth is particularly important, as the color allows for visibility of the blood's characteristics, such as its color and any patterns that may be significant for an investigation.

Other methods, such as pouring the blood into a container, can lead to spills or contamination that may hinder evidence collection and analysis. Additionally, using a vacuum could create suction forces that may alter the sample's composition, whereas spraying with disinfectant is generally not advisable for collecting evidence, as it could obliterate crucial biological information needed for forensic work. Thus, absorbing blood with a clean cloth stands out as the most effective and appropriate method for collecting this type of evidence.