While a cause of death had not been determined and there was no obvious sign of trauma, a police source told the New York Daily News investigators were suspicious because Descoings' cellphone was found on a third-floor landing as if "it had been flung out the window" of his seventh-floor room at the Michelangelo Hotel.
Descoings, 52, was director of the Institute of Political Studies in Paris.
His body was discovered after colleagues asked the hotel staff to check on him after he failed to arrive for a conference at Columbia University. There was no sign of forced entry and hotel staffers told police he had checked in alone.
Police said he may have been alive as late as 9 a.m. Tuesday when staff heard what sounded like snoring through his door, the Daily News said.
"We haven't ruled out foul play," city police spokesman Paul Browne said. "We're investigating the possibility if there was somebody else in the room."