The presumptive reagent fluorescein for detection of dilute bloodstains and subsequent STR typing of recovered DNA

A presumptive reagent for dilute blood detection other than luminol is fluo rescein. The sensitivity of fluorescein approaches the sensitivity of detec tion levels of luminol. The fluorescein detection method offers the advanta ges of working in a lighted environment, and the reaction persists longer t han luminol. A series of diluted bloodstains, ranging from neat to 1:1,000, 000, was placed on a variety of substrates. Three sets were made per substr ate. One set was exposed to fluorescin, one set was exposed to luminol, and one set served as an uncontaminated control. The fluorescein signal persis ted longer than luminol. However, background staining for fluorescein was o bserved on some substrates within 30 s to 1 min, and no background staining was observed for luminol. Stains on non-absorbent surfaces were detectable at 1:100,000 dilutions, and stains on absorbent surfaces were detectable u sually at no more than 1:100. The sensitivity of detection of fluorescein w as comparable to that of luminol in this study. In all cases, where suffici ent DNA was recovered, typeable results at all 13 core CODIS STR loci were obtained from treated bloodstains and controls. The results from STR typing indicate that there was no evidence of DNA degradation.