Fluorescence Detection of Blood Impressions with Acid Yellow

Blood impressions are periodically encountered at crime scenes and on exhibits.  They are relatively infrequent in nature, but are much more powerful evidence than conventional transfer impressions.  They are associated with serious crimes against people, and are frequently recorded in the blood of either the person committing the crime or the victim, often establishing a close connection in time between the two.  They are far more inculpatory in nature.  Many reagent choices exist that darken blood impressions on lighter substrates, but the introduction of acid yellow 7 in 2005 extended the visualization of blood impressions on dark surfaces through fluorescence.  The simple three-step process will be demonstrated and discussed.​