The crime scene team uses an immunochromatographic procedure for the qualitative indication of human blood. At crime scenes, such testing is intended for selective use when human origin of suspected bloodstains is questionable and/or when the determination of indication of human origin is time sensitive. This test is intended for use on stains that have tested positive using the phenolphthalein test. Limited sample size may preclude the use of this test to allow future DNA testing.
In the image below, the left test strip is an example of a positive reaction for human blood while the right test strip is an example of a negative test. The upper, darker purple line is a control band indicating the test functioned properly (it is positioned next to a “C” on the side of the test strip indicating “control”). The lower, lighter purple band, visible only on the positive reaction to the left, is the test band (next to “T” on the strip) that only appears when human blood is detected. The oval depression at the bottom of the strip is where the sample to be tested is applied (next to “S” for “sample”).