A body recovered from a water body does not necessarily imply that the death was due to drowning. If the person is alive when he enters the water, the diatoms will enter the lungs when the person inhales water while drowning.
The Maharashtra (ATS) relied on a forensic test known as diatom tests for leads in the alleged murder case of Mansukh Hiran. A look at what a diatom test is and when it is used.
Newsletter | Click to get the day’s best explainers in your inbox
What is a diatom test?
Diagnosis of death by drowning is deemed as a difficult task in forensic pathology. A number of tests have been developed to confirm the cause of such deaths with the diatom test emerging as one of the most important tests. The test entails findings if there are diatoms in the body being tested. Diatoms are photosynthesizing algae which are found in almost every aquatic environment including fresh and marine waters, soils, in fact, almost anywhere moist.
What is the science behind the diatom test
A body recovered from a water body does not necessarily imply that the death was due to drowning. If the person is alive when he enters the water, the diatoms will enter the lungs when the person inhales water while drowning. These diatoms then get carried to various parts of the body, including the brain, kidneys, lungs and bone marrow by blood circulation. If a person is dead when is thrown in the water, then there is no circulation and there is no transport of diatom cells to various organs.
Diatom analysis is considered positive only when the number of diatoms recovered from the body is more than a minimal established limit. Forensic experts also correlate the diatoms extracted from the body and the samples obtained from the water body where the drowning took place to ascertain the place of drowning. “The result of a diatom test will be different if a person is thrown in the water after he is dead,” Dr S C Mohite, Professor and Head of the Department of Forensic Medicine, told The Indian Express.
Is the Diatom test reliable?
“Yes. It is reliable unless and until the deceased person has been drinking water from the same source of water before his death. For example, a person is drinking water from a well, then the diatoms from the well will be found in the body and so if he has drowned in the same well, then the diatom test will not be reliable.
Also, the test will be negative if the person died instantly after falling into the water,” said Mohite. He added that the diatom test need not be done if classical signs of drowning — like froth at mouth and nostrils, cadaveric spasm, presence of water from drowning medium is seen in stomach and oedema of lungs — are present.
What have the ATS found so far in Mansukh Hiran’s case?
The body of Hiran, who knew how to swim, was found with a cloth mask around his mouth, and the mouth was stuffed with pieces of cloth. While doctors at Chhatrapati Shivaji hospital in Kalwa, who conducted the post-mortem examination, reserved their opinion on the cause of death, they said there was no external injury on the body. A diatom test was done at JJ Hospital’s forensic laboratory, which has remained inconclusive. ATS officials are pursuing two angles, one that Hiran was alive when he was thrown in the creek or he jumped on his own. The samples have now been sent to Haryana forensic science lab for further investigation.
Source: Read Full Article