Possibilities of differential diagnostics of livores mortis and bruises at different stages of the time since death using laser polarization methods

One of the urgent problems of forensic medicine remains the detection of hemorrhages in soft tissues during examinations of decayed corpses, because late cadaveric phenomena significantly distort the primary morphological picture, thereby complicating the examination. A change in the color of the skin after a few days or later after death most often makes the macroscopic diagnosis of hemorrhages impossible, in particular, their differentiation with livores mortis.The aim of work. To investigate the possibilities of detecting and differentiating bruises in areas of livores mortis at different stages of the time since death by the Muller matrix analysis of polarization images of optically anisotropic polycrystalline networks of human soft tissues. Material and methods. Skin sections with subcutaneous fatty tissue were collected from corpses of persons who died from mechanical injuries. The obtained samples were divided into two groups: intact samples of livores mortis at the stages of hypostasis and imbibition and with existing hemorrhages with a known time since death. Tissue research was carried out using a laser polarimeter of a standard scheme.Results. According to the results of the study, it was established that the values of the statistical moments of the 3rd and 4th orders (S3, S4) of the intensity distributions of laser images of the skin show a statistically significant (р1<0,001) difference between intact areas and when bruises and livores mortis are combined. The values of asymmetry and excess (S3 from 1,23±0,032 to 1,56±0,038; S4 from 1,49±0,024 to 1,94±0,021) for intact samples of livores mortis changed with increasing interval of time since death. Similar changes in S3 and S4 (S3 from 1,54±0,031 to 1,83±0,037; S3from 1,82±0,026 to 2,11±0,023) for skin samples in the areas of localization of livores mortis with existing bruises.Conclusions. Thus, it can be stated that the application of the Mueller matrix analysis method of polarization images of optically anisotropic polycrystalline networks of soft human tissues is effective in detecting and differentiating bruises in the areas of cadaveric spots at different stages of the postmortem interval by conducting a statistical analysis of the values of the statistical moments of 3rd and 4th order.