When police came knocking on Friday night, and before they could say anything, he uttered: I am the one who gave that interview to Channel 4It was his second interview to Channel 4 on Friday night (India time) that led investigating authorities to 24-year-old Mehdi Masroor Biswas’s whereabouts in Bengaluru. Even as he was opening up to the correspondent of the UK-based channel in a call lasting just over two minutes, police and internal security agencies were in waiting to track the man who handled what is recognised as the most influential pro-Islamic State (IS, or ISIS) Twitter account ‘@ShamiWitness’.Within hours after the call ended, police were knocking on his one-bedroom-hall-kitchen flat located near Ayyappa temple in Jalahalli in West Bengaluru. When they landed at his doorstep around 11:45pm, it was as if he was expecting them. Before the police could even say a word, Biswas told Hemant Nimbalkar, joint commissioner (Crime), who was heading the operation, “I am the one who gave that interview to Channel 4.”What Biswas or Channel 4 did not know was that the second interview was virtually engineered by the police and intelligence agencies. Knowing it was going to be a live interview, authorities in Delhi, Mumbai, Kolkata and Bengaluru were on high alert to trace the call. At the hour of the live interview which took place around 8pm India time, the anti-terror authorities were following, through ultra-tech tracking devices, calls being made from London to especially Bengaluru.Announcing the arrest, Bengaluru police commissioner M N Reddi said they had pulled off a meticulously planned operation. A source, closely connected with the entire exercise, said they were in the dark about the existence of Biswas till Channel 4 broke the story that a pro-ISIS Twitter handler operated from Bengaluru. The whole of Friday was spent in trying to locate him.The entire intelligence network of the country and in London, from where Channel 4 operates, swung into action with just one aim — to trace the whereabouts of Mehdi Masroor Biswas. His Twitter and Facebook accounts led to an IP address.Next, police and intelligence agencies began to focus on the Channel 4 team. “We asked them to give us the phone number, but did not get the desired result,” a source said. The team was convinced into conducting a second interview on Friday by leading them to believe the man had been tracked and was close to being arrested by Indian agencies, the source said. This ploy was engineered with the help of independent sources other than police and intelligence sleuths.“We were expecting them to dial a number in India. Hence, sleuths had their eyes peeled on all telephone networks like GSM, CDMA and landlines.They knew it would be an incoming call from London, specifically from Channel 4. A telephone tracking device in Bangalore went active as soon as the interview began. A cellphone number with Jalahalli location was tracked,” the source said, adding things moved swiftly after that.The tracking device, the source said, is sophisticated enough to give information on both the receiver’s identity and his address. In this case, Biswas neither used a fictitious name or address.“It led us to house number A- 29 in Sujata Building, which has 35 apartments in Jalahalli West. The persons residing in the flat told us that they had moved in six months ago. A little more probing revealed the earlier occupant had moved to A-14 on the second floor of the same complex.” When the cops rushed to A-14, the door was opened by a young man, who greeted the team with the dramatic line: “I am the one who gave that interview to Channel 4.”“He was calm and cool. Going by his body language, it seemed as if he was waiting for us,” Nimbalkar said.Police sources say Biswas has not shown any signs of fatigue and is ‘‘fully co-operating’’ with police and intelligence agencies who have been grilling him. “We do not know if Biswas’s parents were aware that he was operating the ISIS Twitter account.His mother frequently came to stay with her son. His father, a retired engineer-turned-homeopath, occasionally visited too,” the police said. Police have sealed his flat and seized his laptop and cellphone. They have sent the gadgets for forensic examination to cull any hidden data. The sustained interrogation seems to indicate Biswas is highly indoctrinated.“He is not bothered with Jammu and Kashmir, Gujarat or the Babri mosque. He is totally focussed on Iraq, Chechnya, the uprising in the Arab world, Israel, and what he calls the Western world’s ill-treatment of Muslims,” police said, adding they would now try to find out how he gravitated toward ISIS. Meanwhile, the search for Biswas was a painstaking one. Apart from call tracking, police also went through Facebook accounts of all persons with the name. More than a dozen Mehdi Masroors showed up. “In the process of elimination done countrywide, we zeroed in on a final photograph,” police said.Much before the IS Twitter handler sparked off unease with news of his presence in India and the subsequent manhunt, two undercover reporters with pseudo names were already on his trail.They befriended Biswas on Twitter over a period of five to six months and gained his confidence through regular tweets.They hinted to him they would like to go to Iraq and take up arms. Before that, they expressed a desire to talk to their role model.They gave Mehdi a number and he called them. At the end of the call, they identified themselves as Channel 4 staff and that is how the first interview came about. After this, Biswas knew his game was up. Had he not called them, he would, perhaps, have still been on Twitter running the ‘ShamiWitness’ account.- Biswas comes across as a very timid and quiet person- The 24-year-old engineer was extremely passionate about history- A radical, Biswas started reading about Shia-Sunni conflicts over the past few years and began tweeting about it and other issues- He sent direct messages to get in touch with followers without making his conversations public, mostly targeting radical youths in Britain- In order to get noticed, he would create trending hashtags- So popular was his Twitter account that it was almost like an unspoken ritual that new IS joinees would have to follow Biswas- He was extremely interested in wars, especially in the Islamic world- “We are not ruling out the possibility that radicalised youth or anybody interested in joining the organisation could have messaged him to get in touch with the recruiter. We are also not ruling out the possibility that he acted as a middleman and became a source of information for people who wanted to join the war,” a police officer said.Waging war against any Asiatic Power in alliance with the Government of IndiaWhoever wages war against the government of any Asiatic Power in alliance or at peace with the Government of India or attempts to wage such war, or abets the waging of such war, shall be punished.Investigators say Biswas was strongly influenced by the Jihadi movement. However, since he was the sole bread-earner of his family he could not join the “war”. Instead, he decided to do his bit by starting a twitter account and indoctrinating and influencing people towards a cause he held in high esteem.As soon as the sleuths learned about Biswas’s whereabouts, they rushed to apartment A-29 in Jalahalli. But on entering they were surprised to find some bachelors inside. The sleuths then showed them Biswas’s pictures. The boys confirmed that he lived in A-14. The sleuths immediately knocked the door of A-14. Biswas, who was alone in the house, was taken into custody.The sleuths also summoned the apartment owner Srinivasiah to the spot.The owner reportedly told the police that Biswas had approached him directly in 2013 to rent his house.My son told me that his Twitter account was hacked. I don’t believe he had any link with IS. He was very busy with his work from 8.45 in the morning till evening. When I contacted him, he said he did not understand how it happened. I plan to go to Bengaluru and find out what has actually happened —Biswas’s father Mekail Biswas from Kolkata