What should be done before applying chemical techniques for developing latent prints on suspected blood stains?

Before applying chemical techniques for developing latent prints on suspected blood stains, it is crucial to consult a serologist. This step is important because a serologist can determine whether the stain is indeed blood, and if so, whether it is human or animal blood. Understanding the nature of the stain is essential because different chemical techniques may react differently depending on the composition of the stain.

If a serologist confirms that the stain is blood, they may also provide guidance on the appropriate methods for developing latent prints without compromising potential biological evidence. This ensures that the underlying evidence is preserved for any further forensic analysis and does not interfere with the chemical processes that may be applied.

Other methods, such as drying the stains completely or attempting to brush the area before consulting a knowledgeable expert, might risk damaging the sample or leading to erroneous conclusions about the stain's composition. Immediate application of iodine without prior analysis could also result in ineffective or inappropriate processing of the evidence. Thus, involving a serologist first is a critical step in the forensic investigation process.