Police investigations have revealed that Indrani has two daughters, Sheena and Vidhie. "We have proven that Indrani is the biological mother of the deceased female, whose bones were recovered. It can be assumed that they are of Sheena's," police sources told.
In a major boost to police investigations, the dioxyribonucleic acid (DNA) tests run on bone samples, which the Mumbai police had exhumed from Raigad, have matched with the DNA of Indrani Mukerjea, the Forensic Science Laboratory (FSL) in Kalina claimed on Monday. The tests also proved that the samples were those of a female.
Police investigations have revealed that Indrani has two daughters, Sheena and Vidhie. "We have proven that Indrani is the biological mother of the deceased female, whose bones were recovered. It can be assumed that they are of Sheena's," police sources told.
"DNA fingerprinting is a foolproof evidence and fully admissible in a court of law. That Indrani is the biological mother of the deceased, whose bone samples were tested, will help the police make a watertight case against the accused," said an FSL official.
Two weeks back, the Mumbai police had dug up the alleged crime site near the forest area of Gagode Khurd village in Pen tehsil of Raigad district. They recovered a set of skeletal remains – a skull, pelvis, teeth and limb bones – and sent it to FSL for DNA tests. Blood samples of Indrani, Sheena's brother Mikhail and driver Shyamvar Rai were also submitted.
Of the skeletal remains, two molar teeth and femur (thigh bone) was considered for DNA extraction. "We managed to obtain good quality DNA samples from the femur. Also, the tooth pulp did not yield DNA," said a senior FSL official.
Up to seven scientists worked through the week and over the weekends for close to nine hours every day since August 27 to fast-track the DNA tests. "It was challenging to extract DNA from the bones, as the remains were close to three years old," said another FSL official.
The femur bone was crushed and chemically treated to remove the calcium component. "Calcium inhibits the DNA testing process and hence has to be removed. Nuclear DNA was extracted separately from the bone cells and from blood cells of Indrani Mukerjea.
Inside the nucleus of cells are thread-like structures called chromosomes (46 in each cell – 23 inherited from father and 23 from mother). The genetic material in chromosomes is called DNA. DNA profiles of the bones and blood were obtained by subjecting them to Polymerase Chain Reaction (PCR) tests and genetic analysis.
Fifteen universally specified DNA markers on the bone of the unknown sample and the blood sample of Indrani matched. "These markers are highly individualised. One person in tens of a trillion carry that marker. DNA markers of the child exactly match with that of the mother and the father. If the DNA markers of bone, when compared with Indrani, thus matched, we could definitiely prove maternity. The sixteenth marker is Amelogenin, which determines the sex of the sample," said the FSL official.
Blood of Indrani's first husband Siddhartha Das has yet not reached FSL. "We have not conducted paternity tests yet," said officials.
The DNA of Mikhail Bora was mapped and compared with Indrani's profile. "We have conclusively proved that Indrani is the biological mother of Mikhail," the official said.
The FSL in Mumbai receives up to 175 cases of DNA fingerprinting every month, which help solve cases of mutilated remains, murder, rape cases, paternity and maternity disputes and wildlife identification.
Four Steps for DNA testing -
FIRST DAY: Part of Femur (thigh bone) of the skeletal remains was crushed. Bone cells were separated by chemically treating them to remove calcium. Calcium interferes with DNA testing (takes 24 hours)
SECOND DAY: Nuclear DNA was extracted separately from bone and blood cells of Indrani Mukerjea (takes 24 hours)
THIRD DAY: DNA profiles of bones and blood were obtained by subjecting them separately to Polymerase Chain Reaction (PCR) and Genetic Analyser machines
FOURTH DAY: Fifteen DNA markers (combination of chemicals) for the bone and blood samples were compared.
These markers are highly individualised.
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