[Determination of «solar factor» magnitude in mathematical simulation of the process of corpse's temperature change of under conditions of insolation].

Objective: To develop the method of quantitative assessment of the solar radiation influence on the dynamics of postmortem corpse's cooling in determining the age of human death by means of a special modification of a finite-difference (layered) mathematical model.

Material and methods: The studies were carried out on replacing corpse objects of different mass (bags made of dense polyethylene filled with black soil) and on real objects of forensic medical examination - adult corpses of different sexes. All the objects were wrapped in fabric of different colors, imitating clothes, and were studied under conditions of direct solar radiation impact on the body. Temperature of the objects was measured with a highly precise (0.001 °C) digital thermometer in dynamics.

Results: On the basis of the created finite-difference mathematical model, the thermodynamics of objects has been studied and the «solar factor» magnitude has been established depending on the body mass, time of year, clothing fabric brightness (its photoperceptive ability). The formula for calculating the «solar factor» magnitude is proposed for use of its value in the process of simulation the corpse's temperature under the influence of solar radiation and determining the human's postmortem interval.

Conclusion: The ratio of the real postmortem interval and its simulated (calculated) values allowed to estimate a possible error in the death age determination, accumulated over 6.4-8.5 h of observations as ±0.42 h (± 25 min).