The cause of death was not immediately announced, but former president Donald Trump told attendees at a New Year’s Eve party that Knavs was “very ill” and that his wife was absent from that gathering to be with her.

In a short social media statement, Donald Trump said it “is a very sad night for the entire Trump family.”

“She was an incredible woman, and will be missed far beyond words!” he wrote.

Knavs was born on July 9, 1945, in Judendorf-Straßengel, Austria. She was a pattern maker at a textile factory, while her husband, Viktor, Melania Trump’s father, was a car dealer and chauffeur. They lived in Slovenia before moving to the United States.

The couple became American citizens in August 2018, after a years-long immigration process in which they first became legal permanent residents, probably through a family reunification process that Donald Trump had derided as “chain migration” and proposed abolishing during his time as president, The Washington Post reported at the time.

He was referring to a long-standing policy designed to make it easier for U.S. citizens to sponsor their parents and siblings for legal residency in the United States.