Abstract:
Luminol is an effective chemical reagent for the detection and enhancement of latent blood and is widely utilised for this purpose throughout the forensic community. It is characterised by a pale blue chemiluminescent light which is emitted upon reaction of luminol with blood. Many improvements to the luminol formula have been attempted over the years. In this thesis I critically evaluated three new luminol based formulas, one commonly used luminol formula and an alternative to luminol, fluorescein. These reagents were compared and contrasted in terms of sensitivity, longevity of reaction and DNA preservation as well as economic and practical considerations. Blood pattern distortion and destruction is a major disadvantage to using luminol at crime scnenes. Five spray types and five fixatives/ shear thinning agents were evaluated on their ability to preserve the spatial morphology of bloodstain patterns on non-porous surfaces. Lumiscene Ultra showed the highest intensity of emitted light for higher concentrations of blood. However, when blood was diluted to lower concentrations, this intensity was comparable to Bluestar Magnum, Lumiscene and Hemascein blood detecting reagents. All of the aforementioned reagents, however, had a greater sensitivity than the Grodsky formula. Hemascein had the longest reaction time with Lumiscene Ultra and Grodsky having the longest reaction times for the luminol based reagents. All of the reagents showed a certain amount of DNA degradation when compared to a water control sample. Hemascein preserved DNA to a greater extent than the rest of the reagents. Lumiscene significantly decreased the success of DNA profiling success. The ECO spray and spray gun were found to be the best application methods for luminol for the purpose of preserving the morphology of blood patterns. The hand pump sprayer severely affected the preservation of blood patterns. The combination of a zinc fixative, a shear thinning agent called ABA fix and the ECO spray was found to be best at fixing and preserving the morphology and spatial position of blood patterns.