Sources said Khanna -- the former husband of prime accused Indrani Mukherjea -- was brought to the eastern metropolis, where he used to reside prior to his arrest, in the early hours of Monday and taken to various spots where police conducted raids.
Businessman Khanna was arrested by Mumbai police here on August 26, a day after Indrani was nabbed in Mumbai for the murder of her daughter Sheena. On August 27, he was taken on transit visa to Mumbai, where he was interrogated.
On September 2, Mumbai police confiscated Khanna's laptop and finance related papers, in a purported bid to retrace the chats and e-mails between him and Indrani ahead of Sheena's murder in 2012.
In a bid to ascertain if Khanna's alleged involvement in the conspiracy was for financial gain, police have studied Khanna's bank accounts and investment details and took away the papers to Mumbai last week.
Indrani, the wife of former media honcho Peter Mukherjea, and her former driver Shyam Rai, are the other people charged with killing Sheena in 2012 and disposing of her body.