Estimation of the Time of Deposition of Bloodstains

The development of powerful and robust DNA typing strategies has made it is possible to ascertain with a high degree of certainty whether a biological stain found at a crime scene originated from a particular individual. However, the possibility of obtaining additional information from biological stains exists. For example, the ability to determine the relative time since deposition (TSD) of biological stains could provide law enforcement investigators with novel probative evidence by establishing an approximation of the time of commission of criminal offenses. However, no reliable TSD methods are available at present. We have developed a novel strategy for the determination of the time since deposition of dried bloodstains using spectrophotometric analysis of hemoglobin. An examination of the Soret band in aged bloodstains has revealed a previously unidentified hypsochromic shift (shift to shorter wavelength). The extent of this shift permits a distinction to be made between stains that were deposited minutes, hours, days and months prior to analysis. The effects of temperature and humidity have also been evaluated.