Shraddha Walkar murder: Analysis of samples challenging, will take at least 2 weeks, says forensic expert

An FIR was filed on November 10 after receiving a complaint from Walkar’s father.

According to a senior official from the Forensic Science Laboratory, Rohini, the DNA analysis is going to take two weeks as the samples are very old.

“It may not be easy as the condition of the biological samples is questionable and we cannot say how many living cells will be found. We are still getting samples from the investigating team,” said the official.

Over the past three days, police have recovered more than 10 suspected body parts from the forest area, mostly in the form of bones, but said they needed to be verified through forensic analysis.

The official said that it is not a simple sample and requires expertise.

“It is a single person-related case which makes it more difficult,” he added.

Dr Pankaj Shrivastav, in-charge of biology division regional forensic laboratory in Madhya Pradesh’s Bhopal, said that bone is the most difficult part of the body to conduct DNA sampling.

However, with the latest technology, things have become easier.

Noting that teeth are the easiest body parts for DNA testing, he said, “Bone samples are harder to dig in. First bones have to be cleaned and decalcified which takes 3-5 days and then the sampling is done.”

Dr Shrivastav added that if the bones have been lying in a forest, there are chances that wild animals and dogs must have come in contact with it. “There is also a possibility that the animals too brought bones from other living beings and misplaced the human’s bones which further makes it more difficult,” he said, adding that once the decalcifying process is over, whether the DNA sample is of a human or animal is tested. “The sex of the body is also determined. Post this, the paternity test is done where the DNA should match with the parents and siblings,” he said.

According to a senior forensics doctor working with Safdarjung Hospital, DNA matching and identification of the victim is done with blood samples from parents and siblings, and recovered bones can be sampled for the same. “While bones recovered can be used for DNA even after years, we have to recover some bone marrow in it,” he said.

He added that the main issue of DNA extraction from bones is DNA degradation due to environmental factors and the presence of soil-derived inhibitors like humus acids.

So far, a universal method that allows for the extraction of DNA from materials at different stages of degradation giving inhibitor-free DNA samples has not been reported, and new methods are still being searched for and improved.

On Tuesday and Wednesday, the forest remained at the centre of the case with police saying that they recovered at least one “suspected body part”. Police had first accompanied Poonawala to the forest, and later Walkar’s father and brother.