DFO is a ninhydrin analog used for developing latent prints on porous surfaces. Its fluorochrome properties make it especially useful on multicolored surfaces where the background would interfere with subsequent photography. DFO reacts with the amino acid content of fingerprint residue, and it will not interfere with subsequent analysis using ninhydrin, silver nitrate or physical developer. In fact, some labs report that DFO use improves the results gained with ninhydrin. According to the ”Manual of Fingerprint Development Techniques“ published by the Police Scientific Development Branch of the British Home Office, DFO will develop more fingerprints than ninhydrin. Testing in the U.S. indicates that DFO will develop 2 1/2 times as many prints as ninhydrin. Other testing indicates that DFO is also effective for developing latent blood prints. On occasion, DFO will produce lightly colored (pink) latent prints, but its real strength is in its fluorescent properties. DFO fluorescence may be produced using ultraviolet light, blue light and other alternative light sources.
