Due to the development of science technology and the CSI effect, the method used by criminals gradually became intelligent and suspects use detergents and bleaching agents to conceal or eliminate the blood evidence that are invisible to the naked eye at the murder scene. And it is called a latent bloodstain and can be detected by various chemical reagents. Especially, luminol should be used in darkroom conditions however, difficult to use on site due to toxicity and DNA damage.
In this study, for comparison of the luminescence of latent bloodstain after BluestarTM application in quantitatively by densitometry image analysis to the each factor such as cotton fabrics, laundry detergents, bleaches and laundry methods.
As a result, compared with T/C fabric, 100% cotton fabric showed the larger luminescent area, 84% (20 cotton count) and 83% (40 cotton count) in 100% cotton fabric, respectively. In case of laundry with bleach, the luminescent area decreased about 46.8% ∼ 100% (20 cotton count), 62.6% ∼ 100% (40 cotton count) and 100% (T/C) in each fabric. And washing with an oxygen bleaching agent showed the larger luminescent area than a chlorine bleaching agent, 73.2% ~ 100% in general washing condition and 10.3% ~ 52.0% washing after boiling at 100 ℃. After sequential washing, the decreasing rates of luminescence were 49.5% (1 and 2), 34.6% (2 and 3) and 19.5% (3 and 4), so the bloodstain removed a lot at first, the removal rates of bloodstain decreased as sequential washing respectively. Since, the BluestarTM reacts with latent bloodstains and shows luminescence, the amount of latent blood is proportional to the luminescent area. Therefore, the each area value obtained from the image analysis can be regarded as the amount of latent blood remaining after washing. This result could be helpful when the latent bloodstain on the fabric washed by detergents or bleaches was found at the crime scenes.