A day before the Dec 23, 2024, rape on Anna University (AU) campus, the sole convict, A Gnanasekaran, had targeted another girl student and tried to sexually assault her in a similar manner. His attempt on Dec 22, 2024, however, failed as a university staff member happened to pass by, prompting Gnanasekaran to pretend as if he was merely scolding her.The girl, and her boyfriend, who were cornered by him in an isolated location on the campus, came forward to testify against Gnanasekaran in the trial court. Though they fumbled in identifying him during the test identification parade, both confirmed his role later and told the court that it was out of fear that they did not identify him.Their deposition, along with other clinching evidence such as Airtel call records, forensic analysis of Gnanasekaran’s mobile phone, and the victim’s courtroom statement confirming that no ringtone was heard during a 143-minute window on Dec 23, 2024, proved critical in ensuring a life sentence for Gnanasekaran.Investigators found that Gnanasekaran, who used an Airtel SIM, had made his last call at 6.29pm on Dec 23. He then switched his phone to flight mode until 8.52pm. During this window — the exact time when the crime took place — there were no incoming or outgoing calls or messages. Airtel submitted this data in court and confirmed the phone’s status.Kotturpuram assistant commissioner Bharathiraja, who led the investigation, said the phone seizure proved decisive. After the girl’s complaint, police drew up a list of known usual suspects in the area and zeroed in on Gnanasekaran within 24 hours. “His unusual gait captured on CCTV near the crime scene was a key lead, supported by mobile location data, that led to his arrest,” said Bharathiraja, whose team had submitted more than 200 pages of evidence, including prior offences with a similar pattern.As for the possibility of the involvement of more people in the rape, special public prosecutor Mary Jayanthi said, “there was no other ‘sir’ as alleged. The evidence was clear”. The opposition parties had earlier raised slogans asking, “Who is that sir?” in reference to this claim.Meanwhile, Gnanasekaran’s counsel argued that the 30-year term without remission violates his constitutional rights. He said they would file an appeal against the verdict.