Identification of different body fluids through novel deep blue autofluorescence

Identification of different body fluids at crime scene is imperative to know about its source and the type of crime committed. Non-invasive fluorimetric techniques for the identification of body fluids rely upon the aromatic amino acids, which are not always prevalent in many proteins. Novel fluorescence technique, known as deep blue autofluorescence (dbAF), is independent of aromatic amino acids fluorescence, and can differentiate different body fluids. Contributed mainly by carbonyl group of amino acids, this auto fluorescence shows emission in deep blue (~400-600 nm) region after exciting at the edge of the long wavelength UV range (~360--380 nm). The present study demonstrate the first ever report of deep blue autofluorescence in the identification of different body fluids like, urine, saliva, blood, semen and vaginal sample. dbAF of human body fluids were observed to be distinct from the body fluids of dog, and thus provides a prospective alternative to differentiate human and non-human body fluids. We also demonstrated that dbAF decreases over the time window of 7 days, however it was not completely diminished and still detects the different body fluids. Since all body fluids are inherently fluorescent, present technique could be a novel approach for the identification of various body fluids at crime scene during forensic investigation.