What is the best way to test blood at a crime scene?

The phenolphthalein test is a widely recognized method for detecting the presence of blood at a crime scene. This test works by reacting with hemoglobin in the blood, producing a pink color when blood is present. It is valued for its sensitivity and ease of use, making it suitable for field testing.

In a forensic context, the phenolphthalein test can help investigators quickly confirm whether a suspected stain is blood, guiding subsequent investigative steps. Blood detection is crucial for developing leads and establishing links in criminal cases.

While other tests might also detect substances or blood components, they may not be as suitable or specific for confirming the presence of blood as the phenolphthalein test. For example, an HIV test is specifically for detecting the virus in a person's blood, not for identifying blood at a crime scene, and a benzydine test has largely fallen out of favor due to safety and reliability concerns. A chemical dye test can identify blood as well but is not as commonly used as the phenolphthalein test in initial field-testing situations.