Ivana Trump, the first wife of the former US president, died of "blunt impact injuries" to the torso in an accident, New York's chief medical examiner said on Friday.
The statement did not specify the circumstances, but US media reported that police had been investigating whether the 73-year-old died falling down the stairs at her Manhattan home.
A spokesperson for the New York Police Department told AFP in an emailed statement Thursday that officers responded to a call at Ivana Trump's address on the Upper East Side, and found her "unconscious and unresponsive."
She was pronounced dead at the scene, and the statement added that "there does not appear to be any criminality."
Donald Trump announced her death on Thursday, calling her a "wonderful, beautiful, and amazing woman, who led a great and inspirational life."
He said her "pride and joy" were the couple's three children, Donald Jr, Ivanka and Eric Trump.
Ivana Trump, a model who grew up under communist rule in the former Czechoslovakia, married Donald Trump, then a budding real estate developer, in 1977.
Their first child, Donald Jr., was born later that year. Ivanka was born in 1981 and Eric followed in 1984.
Throughout the '80s, the Trumps were one of New York's highest-profile couples, their extravagant lifestyle exemplifying the flashy excesses of the decade.
Their power and celebrity grew as Donald Trump's property business soared, with Ivana Trump taking on number of key roles in the business.
Their high-profile split, rumored to have been caused in part by Donald Trump's affair with actress Marla Maples, provided juicy content for New York's tabloids.
Donald Trump and Ivana Trump divorced in the early '90s and in 1993 the future president married Maples.
Ivana Trump went on to enjoy a successful business career of her own, developing clothing, jewelry and beauty products and penning a number of books.
She was married four times in her life, once before her marriage to Donald Trump and twice after.
On Friday, a US justice official said depositions of Donald Trump, Donald Jr and Ivanka in New York's civil probe into alleged fraud at his family business had been postponed following her death.