Spade, 55, was found by her housekeeping staff in the bedroom of her Park Avenue apartment at around 10:20 a.m. Tuesday
She appeared to be hanging, and a note was found nearby. Her husband and business partner Andy Spade was in the home at the time, and the couple's 13-year-old daughter was at school. It's not clear how long she had been dead. The medical examiner will perform an autopsy.
Officials said she was found with a red scarf around her neck attached to a doorknob. The officials were not authorized to speak publicly and spoke to The Associated Press on condition of anonymity
Spade created a line of sleek handbags in the early 1990s that created a smash. Her company, Kate Spade New York, has over 140 retail shops and outlet stores across the U.S. and more than 175 shops internationally.
Julia Curry, a spokeswoman for the company, said that "Kate will be dearly missed" and "our thoughts are with Andy and the entire Spade family at this time."
Kate Spade was born Katherine Brosnahan and grew up in Kansas City, Missouri. While working as an accessories editor at Mademoiselle magazine, she and her husband Andy launched the company in their New York apartment in 1993.
She started the company based on six shapes of bags that she thought every working woman needed. It created a smash.
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From the original boxy handbags, she expanded into shoes, luggage and other accessories, as well as a home line, stationery and three books. Spade won multiple awards from the Council of Fashion Designers of America and was named a "giant of design" by House Beautiful magazine.
She walked away from the company in 2007, a year after it was acquired from the Neiman Marcus Group for $125 million by the company then known as Liz Claiborne Inc. In 2017, Coach, now known as Tapestry, bought the brand last year for $2.4 billion.
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Spade and her husband - brother of comedian David Spade - started a new handbag company a few years ago, Frances Valentine. And she changed her name to Katherine Noel Frances Valentine Brosnahan Spade.
Spade is survived by her husband and her daughter, born in 2005.
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If you need someone to talk to about suicide, you can find several helpful resources here at the website for the Los Angeles County Public Health Department.
WABC-TV and the Associated Press contributed to this report.