What should be done before applying chemical techniques to suspected blood stains?

Before applying chemical techniques to suspected blood stains, it is essential to examine the stains by a serologist. This step is crucial because serological examination can help determine the type of biological material present, whether it is indeed blood, and if so, what species it comes from. Identifying the blood's origin assists forensic analysts in deciding the appropriate chemical tests to apply, ensuring that the analysis is relevant and accurate.

Conducting serological tests beforehand can also help provide context, such as differentiating between human blood and animal blood, which may direct the investigation in different ways. This careful assessment avoids potential contamination or misinterpretation that could arise from applying chemical techniques prematurely. Overall, the serological examination serves as a foundational step that influences subsequent analytical methods in forensic investigations.