The findings showed that, when using naturally black hairs, mt333DNA was always amplified from a 5-centimeter length of hair sampled within a region 11 centimeters from the hair root but was not always amplified from a region adjacent to the hair root and was hardly ever amplified from regions further away from the hair root. When using naturally white hairs, mt333DNA was amplified from all specimens up to a length of 31 centimeters. When naturally black hairs were stained with an oxidation-type hair-staining formula, mt333DNA was never amplified even from the hair root region, although staining white hairs did not affect the amplification of mt333DNA. Dark brown DNA preparations, used in cases showing no response on PCR, completely inhibited the amplification of mt333DNA even after addition of purified DNA. The researchers found that hydrogen peroxide induced formation of water- soluble melanins from insoluble melanins, suggesting that the formation of water-soluble melanins, which occur in naturally black hairs, may be caused by oxidation with air. 3 tables and 6 references