How does Amido black reveal blood at a crime scene?

Amido black reveals blood at a crime scene by specifically attaching to hemoglobin in the blood. Hemoglobin, which is a protein found in red blood cells, has components that Amido black can bind to, thus allowing for the visualization of bloodstains. When Amido black is sprayed onto a surface that contains blood, it interacts with the hemoglobin, resulting in a distinct color change that enhances the visibility of the previously latent bloodstains.

This feature makes Amido black particularly useful in forensic science, as it aids crime scene investigators in locating blood that may not be immediately visible to the naked eye. The employed chemical's specificity towards hemoglobin is crucial in ensuring that blood is accurately detected, allowing for better evidence collection and analysis at crime scenes.