A study conducted by Chantal Fregeau et. al. intended to ascertain the effect of seven blood enhancement reagents on the succeeding Profiler Plus fluorescent STR DNA analysis of fresh or aged bloody fingerprints placed on porous and nonporous surfaces. Amido Black, Crowle's Double Stain, 1,8-diazafluoren-9-one (DFO), Hungarian Red, leucomalachite green, luminol, and ninhydrin were tested on linoleum, glass, metal, wood, clothing, and paper. Luminol, Amido Black, and Crowle's Double Stain showed the greatest sensitivity and exposed highly diluted (1:200) bloody fingerprints. This study stated that long-term exposure to these chemicals may affect the 'integrity' of the DNA molecules. It also affirmed that PCR STR DNA typing procedures render superb results when used in 'concert with fluorescence-based detection assays' after fingerprint identification.