Scientific investigation and cyber forensics played an important role in the investigation of the Pollachi sexual assault case. Around 90% of evidence in the case was digital in nature.

Following the arrest of the first five accused, namely N. Sabarirajan, K. Thirunavukkarasu, M. Sathish, and T. Vasanthakumar, and R. Mani alias Manivannan the investigators found a large number of videos of sexual assaults on the mobile phones and other electronic gadgets of the accused. Sensing danger, some of them had discarded their phones. But the videos found helped investigators identify the accused as well as the survivors.

“A team of three forensic experts employed morphological comparisons and other techniques to identify the persons in the videos,” said CBI Public Prosecutor V. Surendra Mohan.

Metadate matching

The forensic experts also analysed the metadata of videos and images from Thirunavukkarasu’s iPhone. They had GPS locations, which helped investigators establish the scene of the crime. These locations from metadata were matched with locations of the scenes of crime. Other aspects in the video, such as articles on the walls of the house of Thirunavukkarasu at Chinnappapalayam near Pollachi, where most of the sexual assaults took place, also helped identify the scene of the crime.

“The forensic experts also matched the date and time of the videos from the metadata with call data records to unearth evidence,” added Mr. Mohan.