Objective To investigate the relationship between changes in the liver computed tomography (CT) images and the postmortem interval (PMI) of rabbits 129 h after their death due to hemorrhagic shock. Methods CT scanning was used to investigate the hemorrhagic shock death model in 23 rabbits to identify the postmortem cerebral changes from 0 h to 129 h after death. Results The liver or lumbar area in the liver window showed the following characteristic changes: from unchanged, to rapid shrinkage, to slow shrinkage; the mean CT values of the liver initially increased and subsequently decreased. The regression equations for the relationship between the two indices and PMI were established by surgery, and they all had statistical significance (P ＜ 0. 01). Conclusion CT scanning can accurately show changes in the rabbit liver after death. The mean CT value of the liver tissue is more sensitive for inferring early PMI. Furthermore, the liver area/lumbar area ratio parameters are more sensitive for inferring mid-late PMI.

Objective To explore the feasibility of individual identification based on the 2D-3D face image superimposition in Han individuals.Methods The 2D video surveillance images(including front,left and right side)and high-precision 3D face models of 10 Han individuals were collected,and Autodesk 3ds Max 2018 software was used to perform perspective matching on the 3D face models,and superimposed them on the 2D images,and the mean values of the distances between corresponding 11 feature points in the 2D-3D face images were calculated.The superimposition of 2D-3D face images from the same individual was defined as the matching group,and the superimposition of 2D-3D face images from different individuals was defined as the non-matching group.Results In general,the average distance ranges of the corresponding feature points between the matching group and the non-matching group did not overlap(P<0.05).Conclusion The non-overlapping mean range preliminarily indicates that the individual identification method based on the overlay comparison of 2D-3D face images described in this paper is feasible for Han individuals.

OBJECTIVETo explore the temporal pattern of postmortem color changes in the pupil region of the cornea for noninvasive estimation of the postmortem interval (PMI).

METHODSTwo rabbit models of air embolism and drowning were established in a dark room at a temperature of 20 ℃ with a relative humidity of 30%. The corneal images of the rabbits were acquired using a digital camera at two-hour intervals within 72 h after death. The pupil region on the corneal images was segmented using computer image processing technique (MATLAB), and the parameters of 6 image color features (RGBHSV) were extracted. Regression analysis was used to analyze the relationship between these parameters and the PMI, and the effects of different death causes on the changes of the corneal color features were also assessed.

RESULTSWithin 72 h after death from different causes, the R, G and B values of the pupil region on the corneal images all tended to increase with the PMI, showing a good fitting with the PMI ( < 0.01). No significant correlation was found between the values of H, S and V and the PMI (>0.05). The R, G and B values in the pupil region on the corneal images showed consistent variation trends after death from the two causes, and their correlations with PMI were also similar. The measured values of R, G and B in air embolism group were greater than those in the drowning group.

CONCLUSIONSThe postmortem color changes of the pupil region on corneal images follow an identifiable temporal pattern and can vary across different causes of death. The regression equations established in this study provide references for non-invasive and objective estimation of the PMI.