Dying along with Krupinski, 70, in the tragic accident were his wife Bonnie, also 70, their grandson Will, 22, and the plane's pilot, Jon Kenneth Dollard, 47.
As the Daily Mail reported, TV star Stewart paid tribute to the family at Krupinski's funeral on Friday, but questions linger about how close her relationship was with him.
The couple met Martha in the early 1990s and in 2013, their estranged daughter Laura alleged her father and Stewart were having an affair, a charge that's been vehemently denied.
New York socialite Laura told Page Six that her father Ben cut her off after she found out about a supposed affair he was having with Martha.
Laura, a former model and mother of Will, said years ago that she became suspicious when she saw her dad and Stewart looking cozy in Palm Beach, Florida, during a vacation.
According to Laura, she waited years before telling her mother.
When she brought it up, Laura claimed Krupinski denied it, insisting he was just close friends with Stewart.
He allegedly called his daughter "crazy," while her mother got angry and wouldn't return her calls.
Laura contended her father then cut her off from her $26,000 monthly allowance and her parents kicked her out of her home.
At the time, Stewart's spokesperson denied Laura's claim and said she was friends with the couple.
According to a Page Six source in 2013, "The family has supported Laura financially for 47 years, but she has some personal issues. They hope that she can get some help to subdue her demons."
On June 8, Stewart spoke affectionately about her friends as hundreds of people showed up at First Presbyterian Church of East Hampton in New York for the Krupinskis' funeral.
Ben had renovated homes for the rich and famous. In addition to Stewart, Krupinski had worked for Billy Joel and Christie Brinkley.
Stewart loved his "extraordinary" work as he renovated her 24-room house.
The celebrity chef and lifestyle guru was married to Andrew Stewart from 1961 to 1990 and has played the field ever since.
The plane carrying the Krupinskis crashed off the coast of East Hampton, Long Island, New York, killing all aboard.
Gallery owner Terry Wallace claimed when Stewart was released from prison in 2005, Ben "took his plane and got her."
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