A new application of genetics in criminology

The medical examiner will be able to find out the time of death by genes

Sergey Vasiliev, Naked Science

As you know, Sherlock Holmes recognized only the knowledge that could be useful to him in investigations. Nowadays, he would undoubtedly have to add genetics to the arsenal of useful sciences. In an article published by the journal Nature Communications (Ferreira et al., The effects of death and post-mortem cold ischemia on human tissue transcriptomes), it finds a new detective application: establishing the time of death.

Pedro Ferreira and his colleagues from the Portuguese University of Porto investigated changes in the activity of genes that spread through tissues within 24 hours after death. In fact, even after a complete stop of electrical activity in the brain, the cells of the body do not die immediately. Experiments on fish have shown that some genes remain active for several days after that.

The authors analyzed RNA molecules that are synthesized on the basis of DNA of active genes and serve as a matrix for protein synthesis. In some cells, these processes can continue for quite a long time after the death of the organism as a whole, until it completely exhausts the available reserves of energy or substrates for biochemical reactions.

Scientists studied this activity in samples of 36 different tissues obtained from 500 donors for up to 29 hours after death. It turned out that the work of post mortem genes varies significantly, but computer analysis allowed us to identify four types of tissues, the study of which will allow us to accurately determine the time of death: subcutaneous fat, lung cells, thyroid gland and skin areas exposed to sunlight.

© Ferreira et al., 2018

Ferreira and his co-authors have developed an algorithm that can be used for examination and, after conducting studies of these four tissues, determine the time of death – theoretically – with an accuracy of nine minutes. Of course, in real "field" conditions, such accuracy is unlikely to be achievable, but genes will still give a more accurate result than traditional methods, some of which have been used since the days of Sherlock Holmes.

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