Reports in Russian media said Mr Antov, 65, had fallen from a window at the hotel in the city of Rayagada on Sunday. Another member of his four-strong Russian group, Vladimir Budanov, died at the hotel on Friday.
Superintendent Vivekananda Sharma of Odisha police said Mr Budanov was found to have suffered a stroke while his friend "was depressed after his death and he too died". The Russian consul in Kolkata, Alexei Idamkin, told the Tass news agency that police did not see a "criminal element in these tragic events".