BHOPAL: Voice-sampling technology and the steely nerves of two police officers braving Covid-19 have led to the arrest of a history-sheeter on Saturday for the rape of a blind bank employee in Bhopal a week ago.The case posed unique challenges for police. First, the survivor couldn’t describe the rapist, apart from his voice. So, police had to get suspects to say the same thing the attacker had told her during the sexual assault so that she could identify him.Second, the suspects were in a containment zone. SHO Chandrakant Patel , a batchmate of Devendra Chandravanshi , the first police officer to die from Covid-19 in MP, admits he was nervous about stepping into a containment zone.But determined to get justice for the 53-year-old survivor, he fought off his fears. SP (South) Sai Krishna S Thota, who led the investigation, joined him. Clad in PPE, the two of them patrolled narrow lanes and bylanes on motorcycles to track down suspects.The one they nabbed turned out to be a 25-year-old burglar, Sahulal alias Manoj Kol , who got back into crime as soon as he was released from a prison a few weeks ago. He gave cops a hard time, and confessed only when police showed an app on the woman’s mobile found on him — it was an app to follow commands from the visually challenged.Police had little to go on when they began the investigation. The woman had been assaulted at home by someone who had entered from the balcony and left by the main door, locking it from outside. At first, it was thought he had taken away only her phone. Then, police realised that the rapist had taken Rs 30,000 in cash and silver ornaments.Police managed to track the stolen phone to a containment zone after which the signal was lost as the rapist broke the sim card. “Five Covid-19 cases have been reported here. I had to ensure that I don’t expose my team to the risk of infection,” SP Thota told TOI.When the loot list came out, investigators started drawing up a list of hardcore burglars of the area, whose behavior pattern matched the crime scene and the survivor’s description, said Patel.The informer network was activated and 25 suspects were shortlisted. Thota and Patel, clad head to toe in PPE, patrolled the streets on bikes to track them down. “In fact, the PPE suits helped as people didn’t think we were policemen. They took us for health staff and the suspects didn’t try to run away,” said Patel.Police detained all 25 suspects and got them to repeat the threat the rapist had made to the woman. With these recordings, they went to the survivor, who picked out Kol, say police.He was brought in for questioning. Thota and Patel, clad in PPE, interrogated him. “He proved a tough nut to crack and denied everything. But when we confronted him with the evidence – the phone and the app for the blind – he knew there was no way out,” said Patel.He had spent all the loot on gambling and drinking. “He showed no remorse for the rape. I haven’t interrogated a more hardened criminal in 13-14 years of policing,” said Patel.