The estimation of blood stain age from the spectrophotometric properties of ammoniacal blood stain extracts

Abstract

The visible absorption spectra of a series of blood stains up to 15 years old have been examined and found to vary in a regular manner with age. A quantity called the “ α s ratio” (analogues to the a ratio of Kind et al., Forens. Sci., 1 (1972) 27) has been derived and calculated for all blood stains examined. It is suggested that this parameter can give a useful indication of blood stain age up to periods of 10–15 years after stain formation. The ammoniacal extract used for the determination can also be used for determination of the ABO blood group by the method of Kind and Cleevely.