What is an appropriate method to collect a dry stain?

Using distilled water is the most appropriate method to collect a dry stain. Distilled water is pure and free from contaminants, which makes it an ideal solvent for gently rehydrating and dissolving substances found in dry stains without introducing any additional chemicals that might interfere with subsequent analysis or testing.

When collecting a stain, it is crucial to avoid using substances that could alter the sample's integrity, which is why other options, such as alcohol or saline solution, may not be suitable. Alcohol can denature proteins or change the chemical composition of the stain, while saline solution could introduce ions that may affect the stain's properties. A wet cloth might also lead to excessive moisture, potentially diluting or altering the stain. Therefore, distilled water provides a controlled approach to safely rehydrate and collect dry stains for forensic examination.