Forensic scientists are able to determine with high accuracy how long ago a person died. The process of decomposition of the body, as well as other changes, occur in it at a certain speed, knowing which, it is possible to calculate the moment of death quite accurately. But what if a person died at low temperatures, and his body was frozen? In the cold, the decomposition process slows down or stops altogether. This task is difficult for forensic scientists, despite all the existing modern research methods. Nevertheless, scientists have found a way to accurately determine the time of death, regardless of environmental conditions.
Determining the time of death of a frozen corpse is a difficult task for forensic experts, but scientists have found a way to solve this problem. Photo source: style.rbc.ru
How scientists determine the time of death of a person
The assessment of the time of death is also called the postmortem interval, or the time since death (PND). The precise determination of this indicator is a very important task. The postmortem interval is often important in forensic medical research. For example, this indicator sometimes allows us to reconstruct the chronology of events, narrow the circle of suspects if we are talking about murder, etc.
To assess the time of death, forensic scientists first of all study postmortem physical and biological changes in the body. These include, for example, rigor mortis, cooling, fluid accumulation, etc. It should be noted that the speed of these processes is influenced by many factors, not only environmental conditions, but even the health of a person before death.
To determine the time of death, scientists use a range of methods. Photo source: bigpicture.ru
In addition, to obtain a more accurate result, forensic experts also measure electrical, chemical, mechanical, thermodynamic and other parameters of the dead body. In this way, they check the irritability of the skeletal and smooth muscles, as well as sweat glands. However, all these methods are used in the first hours after death.
When it is necessary to determine the time of death at a later stage, forensic experts conduct studies of insects that participate in the decomposition of the body, and also use a set of other measures aimed at studying changes in the corpse. Taking into account all this data, it is possible to determine the DNS quite accurately. However, determining the time of death from a corpse that was in the cold is still a difficult task.
Why It's Difficult to Determine Time of Death from a Frozen Corpse
In extremely cold environments, traditional time of death methods may not be enough to provide accurate rigor mortis data. In extreme cold, the body cools much more quickly, making it difficult to make estimates based on body temperature. In addition, low temperatures can delay and alter the duration of rigor mortis.
If a person dies at extremely low temperatures, it is almost impossible to accurately determine the DNS. Photo source: pixabay.com
As mentioned above, the decomposition process can also slow down significantly or stop altogether. In addition, at extremely low temperatures, there is usually no activity of insects that participate in the decomposition of the body, such as flies, beetles and other organisms. Snow can isolate the body from the environment, which also slows down the decomposition process.
All this still greatly complicates the determination of DNS. However, in such a situation, modern, advanced molecular methods come to the rescue. These include the analysis of the microbiome, gene expression and protein degradation.
How microbes allow us to accurately determine the time of death of a person
A recent study by scientists has shown that bacteria allow us to accurately determine the time of death of a person even from a frozen corpse. As is known, the main role in the decomposition of the body is played by the necrobiome, that is, microbes that feed on dead tissue. It would seem, how can this help forensic experts?
The thing is that at different stages of decomposition, there are different types of microbes that contribute to the breakdown of tissue. So by taking samples of microbes in a dead body and studying their composition, forensic experts can determine how long ago a person died.
The time of death of a person can be accurately determined by bacteria. Photo source: www.salk.edu
A recent study conducted on pig corpses showed that even at extremely low temperatures, it is possible to accurately determine the time of human death by several types of bacteria: Psychrobacter, Pseudomonas and Carnobacterium. It should be noted that pig corpses decompose in the same way as human corpses. Therefore, they are often used in forensic studies.
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According to the researchers, the above-mentioned bacteria make it possible to determine the DNS for six months after death with an error of about nine days, which is a high figure. This means that the process of decomposition of the body does not stop even at low temperatures, reaching -40 degrees Celsius.
The method developed by the scientists is not yet used in forensic practice, but according to the authors of the work, microbes may soon become the most important part in solving the puzzle associated with determining the time of death of people even in the most extreme conditions.