New York police are attempting to piece together the final hours of the director of one of France's most elite colleges after a medical examiner's report shed no clues on the cause of death.

Flowers, letters and candles are displayed in tribute to Richard Descoings, director of the prestigious Sciences-Po, at Paris Institute for Political Studies on Wednesday. Descoings, was found dead in a New York hotel room on Tuesday afternoon. [Photo/Agencies]

The mysterious demise of Richard Descoings, whose naked body was found in his Manhattan hotel room on Tuesday, sparked emotional tributes from students, politicians and fellow academics, who hailed him as a "visionary" and "idol".

The married 53-year-old headed the highly respected Paris Institute of Political Studies - "Sciences-Po" - and was in New York for a conference but he failed to show up, prompting a search and an eventual discovery of his body.

Ellen Borakove, spokeswoman for the city medical examiner's office, said an autopsy performed on Wednesday was "inconclusive" and that more testing would be done, with results expected in 10 days to two weeks.

Police were investigating after the academic's body was found on the bed in room 723 at the Michelangelo Hotel but said there was no evidence of foul play, despite initial reports suggesting otherwise.

"The hotel had checked earlier in the morning at 9 (o'clock), and he was asleep, at one he was found dead," Deputy Police Commissioner Paul Browne said late on Tuesday.

Descoings had been attending a meeting of the heads of major universities under the auspices of UN Secretary General Ban Ki-moon.

The Frenchman was due to meet four colleagues in the hotel at 9 am, but when he failed to show, they assumed he had left without them.

The tabloid New York Post, citing police sources, said empty bottles of anti-depressants and alcohol had been found at the scene, and the newspaper also reported that two men had earlier visited the academic's room.

Descoings's wife Nadia and other family members arrived in New York on Wednesday and were to remain there until the repatriation of the body.

Descoings drew criticism earlier this year when it emerged that he earned a net salary of 24,000 euros ($32,000) a month with a variable bonus on top, while most university heads in France are paid around 4,500 euros a month.

In an interview with Liberation newspaper in which he defended his salary, Descoings also complained he had been "forcibly outed" by the newspaper Le Monde, saying: "I do not see what my supposed homosexuality has to do with anything."

French President Nicolas Sarkozy and the country's Education Minister Luc Chatel led the tributes.

Sarkozy - who studied at Sciences-Po but failed to graduate - praised Descoings's "exceptional career", saying in a statement that the academic had "devoted his whole life to his chosen cause ... education".

Chatel said France had "lost a visionary spirit" who "revolutionized our higher education".

At New York's Columbia University, students and faculty gathered on Wednesday evening to pay tribute to Descoings.

"He was a friend, a fellow traveler, and this is a great loss for us all," Verillaud Francois, in charge of Sciences-Po's international programs, said.

Mamadou Diouf, a professor of African history at Columbia, said he had dined with Descoings at the inaugural event for the academic conference on Monday, the night before he died.

"He was fit, he seemed very excited to be there ... We laughed, we talked. I could not believe it the next day when I opened my computer, that he was dead," he told AFP.

At the Paris school, hundreds of students and teachers gathered for a tribute that included a moment of silence and speeches recalling the man known as "Richie".

Agence France-Presse