The brother-in-law of the Prince of Wales died Wednesday after falling outside a hotel bar and suffering a head injury, police said.
Mark Shand, the brother of Prince Charles' wife, Camilla, Duchess of Cornwall, was in New York for a charity auction at Sotheby's.
Shand, 62, had arrived at the Gramercy Park Hotel's Rose Bar just before 1 a.m. Wednesday accompanied by a relative, police said. He went out to smoke a cigarette around 2:30 a.m. and fell backward as he tried to re-enter through a revolving door, they said.
He was taken to a hospital, where he was pronounced dead at 11:25 a.m., police said. The cause of his death will be determined by the medical examiner's office.
New York Police Department detectives were at the Manhattan hotel on Wednesday afternoon, taking a look at the locations of security cameras. A worker at a building across the street said detectives had asked if the building had any security video, which it didn't.
A call to the hotel's representatives was not immediately returned.
Shand was chairman of an elephant conservation charity and was known for his work as a travel writer and conservationist. He was the author of several books including "Elephant Tales" and "River Dog: A Journey Down the Brahmaputra."
British royal officials at Clarence House said in a statement that Camilla, Prince Charles and all of her family members are "utterly devastated by this sudden and tragic loss."
"Mark Shand was a man of extraordinary vitality, a tireless campaigner and conservationist whose incredible work through The Elephant Family and beyond remained his focus right up until his death," it said.
Sotheby's said it was "deeply saddened" by the news of Shand's death and it was honored to have helped him raise money for his causes.
Camilla and Charles are due to go on a tour of Canada next month.