It has the competence to use the low copy number (LCN) or Touch DNA, a forensic technique that can derive DNA trace from even minuscule sample unlike regular methods, but the Hyderabad-based Centre for DNA Fingerprinting and Diagnostics (CDFD) did not use it to examine evidence in the Aarushi Talwar-Hemraj Banjade murder case of May 2008.
CDFD director (acting) and molecular staff scientist Dr J Nagaraju told the Hindustan Times, “We have the technical knowhow to use the low copy number or the Touch DNA technique, but we do not use it since it is not reckoned to be a scientifically robust method of obtaining DNA trace.” He added, “This is why we used the regular DNA profiling technique to examine crime-scene samples sent to us by the CBI during its probe in the Aarushi Talwar-Hemraj case.”
The CBI, which closed its probe in the case on Wednesday, had sought the CDFD’s expertise. When asked about whether the CDFD had examined a dried, bloodied handprint gathered from the case’s crime scene, which could have contained the forensic trace of the killer(s) along with one of the victims, Banjade, Nagaraju said: “The CBI had sent us this handprint. We had used the regular DNA technique on it and established that the DNA profile of the handprint’s blood matched with the DNA profile of Banjade’s razor. We did not use the LCN technique.”
In May, CBI’s former director Ashwani Kumar said the agency was planning to seek foreign forensic help to use the LCN technique since it was not available in the country. The CBI had suspected that the handprint, smeared with Banjade’s blood, belonged to a killer who could have leaned on a rough wall portion — to break his fall. Banjade had been dragged to the third-floor terrace of the Jal Vayu Vihar building by the killer(s) from the second-floor flat where Aarushi was killed.
“The samples, gathered by the probe team that arrived first at the crime scene, were either contaminated or proved to be useless in the end,” he said.