CBI books FSL officials for tinkering with forensic reports to let rapists off the hook

New Delhi: Ever since DNA evidence became an indispensable tool for criminal investigations, it has often been used to overturn many a wrongful conviction. But in a disturbing turn of events, the Central Bureau of Investigation on Friday booked a former Deputy Director of the Forensic Science Laboratory (FSL) in Rohini and an ex-Senior Science Officer (SSO) of the same lab for allegedly doctoring forensic reports in a rape case, based on which the trial court acquited the accused.

According to the CBI, AK Srivastava, then Deputy Director Biology/DNA and L Babyto Devi, then SSO, of FSL, Rohini had tinkered with the forensic examination reports of the DNA evidence in at least one other rape case and one case of sodomy and murder with the intention of unduly benefitting the accused in the cases.

In the case where the accused was acquited of the rape charge, re-examination done by a board of three doctors had found that the original forensic report was false in addition to the CBI's own Central Forensic Science Laboratory in Delhi confirming the falsification of the report.

In this rape case, which was from 2013 in Badarpur, the Delhi Police sent at least six evidentiary exhibits of the accused and the victim, including the victim's underwear and vaginal swabs and penal swabs, control swabs, blood gauge and pants of the accused to the FSL, from which DNA profiles could be extracted.

But Devi, who was conducting the forensic examination had claimed that only profiles from two of those exhibits could be extracted. Further, she had claimed in her final report that the DNA from the blood gauge of the accused did not match the DNA generated from the victim's underwear.

In both the FSL board's re-examination report and the CBI's forensic examination, it was not only found that the victim's underwear had a detectable semen sample but that it also matched the DNA profile of blood collected from the accused.

In the other two cases, the CBI's preliminary enquiry has found that Srivastava was himself allegedly involved in doctoring and falsifying forensic reports. While the initial report in these two cases was prepared by Devi and said that no DNA profile could be generated from the evidentiary exhibits, the trial court had ordered a re-examination, which was conducted by Srivastava. In the two separate examinations, it was found that there were significant irregularities in the allele data of the accused persons.

In DNA examinations, scientists usually extract a DNA profile from an evidentiary exhibit and then put it through a process called sequencing. At this point, the components of the DNA, i.e., A, T, G and C are identified, and so is their position in the sample. Based on this, a computer programme identifies the pattern of ATGC in the sample's DNA. This result is then matched with the sample collected from the other party and checked for statistical similarities.

While in the 2012 Samaypur Badli rape case, the CBI has accused Srivastava of tweaking the allele data (ATGC) by overwriting it, the Mahindra Park case of sodomy and murder showed that allele data gathered by Devi and Srivastava from the same sample of the accused did not match, which is a scientific impossibility.