U.S. flag

An official website of the United States government, Department of Justice.

Developing Fluorogenic Reagents for Detecting and Enhancing Bloody Fingerprints

NCJ Number
Date Published
January 2009
65 pages
The main goal of this research was to develop fluorogenic compounds for detecting fingerprints in blood that have suitable sensitivity and stability, enhance and preserve print details, and will work on dark and multicolored substrates.
The study determined that the proposed materials improved upon the current fluorescin/fluorescein and luminal systems in many respects. The reagents and protocols developed preserved detail for substantially longer periods than fluorescein; and solubility and fluorescence under acidic conditions and peroxidase-specific chemistry were all successfully achieved. The oxidation reaction mediated by HP/H2O2 produced fluorescent products in acidic media. The use of Na OAc and PEG MW 35 000 as additives to the reaction mixture accelerated the oxidation reaction. The reduced form of the dyes is soluble at acidic pH (2-5) and is also compatible with strong protein denaturing solutions. The oxidized forms have diminished solubility. Formation of colloidal type precipitates were observed for oxidations conducted in solution at acidic pH. Thus, improvement in detail preservation may be possible. Because of their broad absorption range, fingerprints developed with these dyes were visualized over the range of 400-570 nm, using alternative light sources equivalent to several dye laser excitation wavelengths. Thus, the use of UV-light for visualization, which can damage DNA, can be avoided. The oxidation products are stable, which allows the capture of detailed images after long periods of time (at least 10 months). Improvement in the fluorescence emission is obtained by spraying the treated fingerprint with a solution of higher pH. Promising results were obtained on pig blood fingerprint trials on glass and colored board, using the newly created dyes. Extensive figures and tables, and 50 references

Date Published: January 1, 2009