Date of Submission


Document Type



Forensic Science


Claire Glynn, Ph.D.


Expirated Bloodstains, Saliva in Blood


Bloodstains, Bloodstain pattern analysis, Saliva--Examination, Spectrophotometer


Expirated bloodstains and impact bloodstains have very similar physical characteristics. The main way Blood Pattern Analysts identify bloodstains in based on their physical characteristics. This can lead to difficulty distinguishing between expirated blood and impact spatter. Expirated blood can be identified through the presence of air bubbles, however these are often only present on non-porous surfaces. However, if expirated bloodstains can be identified through the presence of saliva, this can provide an alternative way to identify expirated bloodstains. This study examined if SALIgAE can be accurately used to identify the presence of saliva in blood and thus, be a way to identify expirated bloodstains. Dilutions of saliva to water, saliva to blood, as well as reconstructed expirated stains were created. Expirated stains on white butcher paper as well as five different substrates were produced. The substrates consisted of, carpet, white T-shirt, denim, black T-shirt, and tile. SALIgAE was visually examined for a color change. SALIgAE was also analyzed with a UV-VIS spectrophotometer to obtain quantitative data. The results showed that SALIgAE can identify the presence saliva in dilutions of saliva to blood as well as expirated bloodstains. The spectrophotometer allowed the concentration of salivary α amylase to be determined. This study proves that SALIgAE can be used to accurately identify expirated bloodstains as well as be analyzed by the spectrophotometer to obtain the concentration of salivary α amylase in the sample.