An excerpt from Nicholas Gage’s book, Greek Fire: the Story of Maria Callas and Aristotle Onassis (2000)

In all the reporting on the details of the drama-packed weekend of JFK’s murder and his funeral, one detail that seems to have been hidden from public notice was that one of the few non-Kennedy relatives who received a formal invitation to the funeral, and was asked to stay in the White House was a Greek shipowner named Aristotle Onassis.

I learned the details of that weekend while researching my book Greek Fire (Knopf) about the love affair of Onassis and Maria Callas, whose heart was broken when Ari ditched her for the former first lady.

After the death of Jackie and JFK’s newborn son Patrick on Aug. 9, 1963, Onassis, who was then seeing Jackie’s sister Lee Radziwill, invited the grieving first lady on a cruise on his yacht, which she boarded on October 4, 1963, over the strenuous objections of her husband, who told her “For Christ’s sake, Jackie!  Onassis is an international pirate!”

She went anyway, accompanied by her sister Lee and Lee’s husband Stas Radziwill  and, at the insistence of the President, undersecretary of commerce, Franklin D Roosevelt Jr. and his wife. “to add a little respectability to the whole thing,”  as the President put it.

At the end of the cruise Onassis bestowed on his guest of honor a diamond and ruby necklace reportedly worth fifty thousand dollars.

When Jackie returned to Washington, raving about the trip, she felt guilty about the negative publicity it had raised, so she agreed to her husband’s demand that she accompany him to Texas the following month.

On November 22, 1963, Maria Callas was in Paris and Aristotle Onassis was in Hamburg, Germany, checking on the construction of a new tanker, when they learned the news of the President’s murder.  He called Lee Radziwill in London and she asked him to accompany her and Stas to Washington for the funeral.  The next day Onassis received an official invitation to attend the funeral and to stay at the White House—one of only half a dozen non-Kennedys so honored.

Inside the White House, on Sunday, November 24, 1963, Onassis discovered the raucous atmosphere of an Irish wake. He found himself joking with Bobby Kennedy, Ted Kennedy, Robert McNamara, Ken O’Donnell, and Dave Powers, as well as other family members and close friends.  After teasing Onassis about his fortune, Bobby Kennedy produced a bogus contract pledging half of it to the poor of Latin America.  Keeping a straight face, Onassis signed it in Greek.  He also found time during the weekend to spend a few minutes with Jackie Kennedy in the family quarters and to offer her some words of consolation.

If the press had noted the unusual presence of Onassis at the White House on that historic occasion, the world might not have been so shocked when Jackie announced five years later that she was marrying the Greek tycoon.