After an autopsy, the New York City medical examiner ruled Carlisle Brigham's death accidental; the result of blunt-force trauma to the head and neck from injuries consistent with a fall.
Toxicology tests for alcohol and drugs will be done, as is standard procedure, said the medical examiner's spokeswoman. That could take weeks.
Brigham, 29, was the daughter of James Brigham, an investment banker, who was once the city's budget director during the fiscal crisis from 1978 to 1981.
In 2011, she married Anthony Champalimaud, son of a Portuguese banking family.
On Monday, she was coming down from the fourth floor apartment of a male friend at 191 Orchard Street. She apparently fell from the third floor to the second floor.
Mizanur Rahman, who was leaving for a dentist appointment, found her lying in a large pool of blood at about 10:30 a.m. He said she was not breathing, was cold to the touch, but had a slight pulse. Trained in CPR for his elderly parents, he attempted to revive her by turning her over and giving her CPR.
Other witnesses said Brigham was wearing 5- or 6-inch high heels when she was found.
Carlisle lived of Fifth Avenue on East 12th Street. She reportedly was estranged from her husband of just one year and was staying with male friend when she fell down the stairs.