Police said preliminary investigation found that Nandi was travelling to Mumbai. He was to take a connecting flight abroad for an overseas job. But Nandi has told police that at the last moment, he realised he did not want to leave his ailing wife behind and wanted to return home. He then wrote the threat note on a white card and planted it in the plane’s washroom, hoping that the flight would be aborted. He has told police he was “not in the right state of mind”. Police said forensic analysis has confirmed that the handwriting on the note was Nandi’s. Police found several white cards similar to the one on which the threat note was written with him.

The airport authority said in a statement on Thursday, “In connection with yesterday’s incident involving Air India flight AI 2772 (Kolkata–Mumbai), one passenger was apprehended and handed over to the NSCBI Airport Police Station.” The arrested accused lives in Kolkata’s Sodepur area.

On Wednesday, the plane’s pilot sent a hijack alert to Air Traffic Control after the threat note was found in the washroom. ​The hoax triggered panic and disrupted operations at Kolkata airport.

“For safety reasons, the aircraft was moved to an isolation bay. Security personnel rushed to the spot and surrounded the entire aircraft to begin a thorough search,” an airport official said during the emergency response. It was during the questioning of passengers that Nandi was identified as a suspect and taken into custody. The plane departed seven hours after its scheduled take-off, following mandatory protocol and clearances.