Spectrophotometric evaluation of postmortem lividity: a proposal of a model for negroid ethnic race.

The interpretation of tanatochronological data is a fundamental aspect of the medico legal diagnosis, because it allows to trace back the interval of death. Traditionally, the evaluation of the hypostasis plays a relevant role in the interpretation of such information, despite its well-known limits and fallacies. In order to evaluate the degree of hypostatic area discoloration, the methodology currently used is highly subjective and influenced by several variables. The hypostasis pattern in individuals with V-VI phototype is useless because their post-mortem lividity is not estimable due to the color of the skin. This makes much harder to estimate the interval between the death and the detection of the tanatochronological data. This study is aimed at defining a highly accurate procedure to develop an objective method to estimate the hypostasis' degree of fixation with scientific accuracy on people with darker skin. The technology used is spectrophotometry Antera3D: this device is able to analyse the hypostasis by measuring the mean hemoglobin quantitative level in the skin either before and after a standardized compression, thus obtaining a numerical value that is directly related to the time of death. The method here presented allows analysing the hemoglobin amount in the skin of a dead body, without the influence of the melanin pigment in the definition of the hypostatic area color, therefore enabling us to overcome the objective limits of the direct and empiric estimation of the hypostasis decoloration. By creating a standardized method it's possible to reduce the operator-dependent error and to introduce a valid and applicable procedure in order to estimate the post-mortem interval.