Prescription of death (CSN) is determined in forensic practice, as a rule, by forensic experts using a variety of methods. Modern forensic medicine has a significant arsenal of various scientific approaches, which are based on the assessment of the so-called early and late destructive phenomena. To obtain the most accurate DNS, measurements of electrical, chemical, mechanical, thermodynamic and other parameters of the dead body are used. Separately, there is a method for establishing the CSN during long periods of the post-mortal period using insect necrophage research ( forensic entomology ). With the increase in DNS, the accuracy of its determination drops sharply.
Basic methodological approaches in determining CSN
- Supravital Reactions
- Rigor mortis
- Dead spots
- Corpse Cooling Simulation
1. Prescription of death and supravital reactions (exact method). The study of electrical, pharmacological and mechanical  irritability of skeletal (including facial) and smooth muscles, sweat glands. Used in the first minutes and hours after death.
2. Prescription of death and rigor mortis (approximate method). Measurement of severity, localization, recurrence time and resolution. Used in the first two or three days after the onset of death.
3. Prescription of death and corpse spots (rough method). The time of their occurrence, the rate of disappearance and recovery under pressure are noted. Used  in the first two days after the onset of death.
4. Prescription of death and cooling of the corpse (exact method). This method has found the widest application in practice. This is due to the fact that the cooling process is almost exclusively "physical" and little depends on the "chemistry" of the body. It lasts up to two days and thus makes it possible to make fairly accurate predictions in this way in this time interval. The method is accurate, easy to use, and not expensive, since only an accurate thermometer is sufficient for use. To use the results of measurements in court requires the mandatory use of certified thermometers with periodically renewed metrological control studies.
Explanation of the mathematical model of calculations
Any physical body is cooled " according to Newton " or exponentially. The cooling schedule of a corpse differs from this classical cooling model by the presence of a so-called “plateau”. The onset of cooling in a corpse is not rapid, as for example in a metal block or other solid body. It seems that the corpse does not cool at all at the beginning, but retains its body temperature for some time and only gradually, as if reluctantly, begins to give off heat faster and faster until the cooling process goes into the classical Newtonian cooling phase so as to slow down sharply at the end. cooling. Thus, the cooling curve of a corpse consists of two curves. This is the “upper” and “lower exponential”. Thus, a so-called two-exponential model of calculations is needed to describe the cooling process. For the first time such a model for practical calculations was developed by Marshall and Hoare in 1962. In a modification of Hennßge (1984), this model is the most frequently used in forensic medicine at the present time (the program for calculating the limitation of death).
The problem of the practical use of this model lies in the complexity of calculating the correction factors. The cooling rate is influenced by body mass and cooling conditions. This means not only the ambient temperature, but also the clothing of the corpse, the substrate, the presence of air movement, and humidity. Environmental conditions are taken into account in calculation models by introducing empirically derived correction factors. The most widely used in practice are based on the Hennßge nomogram model for the rectal temperature of a corpse.