Why Jackie Kennedy Quietly Burned Personal Letters and Photos Before She Died (Exclusive Book Excerpt)

In the final months of her life, Jacqueline Kennedy Onassis received a Valentine’s note from a former lover, architect Jack Warnecke. The former first lady had rarely been out of his thoughts, he told her.

According to a new biography — Jackie: Public, Private, Secret by J. Randy Taraborrelli, which was exclusively excerpted in this week's issue of PEOPLE — the note led to a reunion at her apartment several months before her death on May 19, 1994, from non-Hodgkin lymphoma at age 64.

Three decades earlier, Jackie had fallen in love with the architect, who designed the memorial grave site for President John F. Kennedy at Arlington National Cemetery.

Years later, Warnecke shared his memories with Taraborrelli — with one caveat. Out of loyalty to the famously private Jackie, Warnecke asked that everything remain under wraps until a decade after his death. He died in 2010, when he was 91.

Now those details are among the many revealing moments shared in Taraborrelli’s new biography. “So many of the books about Jackie are about the glamour and the celebrity," he tells PEOPLE. "I wanted to write about the human side."

Below, an excerpt from Taraborrelli's new book, Jackie: Public, Private, Secret.

It was nightfall as John Warnecke walked to 1040 Fifth Avenue to visit his former lover, Jacqueline Kennedy Onassis. The apartment was dark and quiet. John Warnecke—better known as “Jack”—noticed a telescope in the corner. Jackie had once told him she often gazed into it to see how the other half lived. He noticed a light from one of the rooms. Wearing a pink chenille sweater over white silk pajamas, she was seated close to the fireplace. Jackie asked Jack to not reveal to anyone what was about to happen, not while either of them was alive, any way.

In [our] 1998 interview, Jack said, “As I took my seat, Jackie handed me a stack of envelopes neatly tied together with yarn. My presence that evening was part of a ritual. Every night that week, she was inviting a trusted friend or family member to her home to take part in it.”

Jackie untied the yarn and took a letter from the stack. She read it before placing it into the fire. He recalled, “There were letters from Jackie’s children, John and Caroline ... There were also letters from Jack Kennedy, Aristotle Onassis, her father, Jack Bouvier and even a few from me.” She held one of the photographs and stared at it. It was her and Jack [Kennedy] on the day of his inauguration. “Keep this for me, will you?” she asked.

Jackie was by her husband’s side in the Dallas motorcade when he was assassinated on Nov. 22, 1963. Some said it sounded like a crack. Jackie Kennedy thought it was the backfire of a motorcycle. Confused, she watched as Jack grabbed his throat and lurched to the left. Rifle shots, all. Three in the course of less than five seconds.

“Jack turned and I turned back,” she later recalled. “I could see a piece of his skull coming off. He was holding out his hand and I can see this perfectly clean piece detaching from his head. Then, he slumped in my lap.”

Less than a year after her husband’s death, architect Jack Warnecke approached Jackie—raising eyebrows among some in her inner circle.

It was in the middle of May 1964 when Jack Warnecke called to ask her out. “On a date?” she asked. “Because I don’t date, Jack, and I never will again,” she said. No, Jack told her, it wasn’t a date. It was just dinner. That night, he showed up at her door with flowers. “But, Jack, I didn’t say yes,” she told him, annoyed. “But you didn’t say no,” he said with a smile. “That’s when it started between us,” Jack Warnecke recalled.

After the president was assassinated, Jackie hired Jack [Warnecke] to design his gravesite at Arlington. Jackie told herself Jack deserved the job. Her friends had to wonder, though. Bobby Kennedy wondered, too. He believed Jack was moving in on Jackie too quickly.

“It’s too soon, Jackie,” Bobby told her. “For what?” she asked. “For this,” he exclaimed. She then leveled with him: “This is none of your business, Bobby.”

In November 1964, she brought Warnecke to the Kennedy compound in Hyannis. “We had dinner—clam chowder—and talked until the sun went down, and then talked beyond that . . . Then, one thing led to another.”

Jackie walked him upstairs to her bedroom, the same one she’d once shared with Jack Kennedy. Much to Jack’s surprise, she wanted to make love, and so they did. The next morning, Jack awakened to find Jackie gone. He found her staring out at the beach. He tried to talk about what had happened the night before, but she didn’t want to. Instead, she asked him to leave. He realized it had been too soon for her.

It was an emotional seesaw: up one moment, down the next. She later told Jack Warnecke, “Everytime I think I’m having fun, I look down at myself from above and can see that it’s all performance art.” 

They dated for three years. In 1966, he planned to propose in Hawaii.

They simply began talking about marriage as if it were a fait accompli, but it bothered Jack that no formal plans were being made, yet. Still, their intimacy didn’t suffer. Warnecke said they had sex not only in the privacy of their bedroom but also in cars and on beaches “and as often as possible. She was sexual . . . alive . . . exciting to be with.”

Soon after, he called to tell her that the expansion of his architectural firm—and their extravagant lifestyle—had left him one million dollars in debt.

After a long silence, her response was a vacant: “Oh?” Jack said he hoped it wouldn’t totally ruin things for them. Before he hung up, he told her he loved her. She didn’t respond. She stopped returning his calls. “Is Mr. Jack coming over today?” little John asked his mother one afternoon. “No, honey,” she said, scooping him up in her arms. “We won’t be seeing Mr. Jack again.”

Jackie married Greek shipping magnate Aristotle Onassis in 1968. It was a turbulent union that ended with his death at age 69 in 1975. Meanwhile, she entered therapy with a psychoanalyst, Dr. Marianne Kris.

“Dr. Kris would never discuss Mrs. Onassis, citing doctor-patient confidentiality,” said Patricia Atwood, Kris’ secretary from 1972 to 1974, in an email. “They addressed Mrs. Onassis’s ongoing PTSD over the assassination, as well as certain nagging issues about their marriage. He went out in a blaze of glory, Mrs. Onassis said, according to one of the notes I read. The way he died had completely robbed her of the right to hate him, she said. Next to that entry, Dr. Kris wrote that her grief was anything but, as she put it, ‘tidy.’”

She discovered Dr. Kris had once treated Marilyn Monroe—long believed to have had an affair with JFK—just one of his many infidelities.

When Jackie confronted her, [Dr.] Kris said she felt no responsibility to inform her about any former patients in the same way she’d never reveal that she’d ever treated Jackie. Marianne asked, “How is this relevant?” to which Jackie responded, “How is that not relevant?”

In her later years, Jackie found companionship with diamond merchant Maurice Tempelsman. Then in early 1994, she was diagnosed with non-Hodgkin’s lymphoma. Two months before her death, she called Warnecke.

It had been about a month since the ritual in her apartment, during which he and Jackie had burned letters in the fireplace. As they talked, Jackie told Jack that after four chemotherapy treatments, her tests had come back clean. She thought she’d beaten the disease.

Then, unbelievably, an MRI showed that it had metastasized to the membranes of her brain and spinal cord. Jack asked her if, in reviewing her life, she had any regrets. She said she wished she hadn’t let Nov. 22, 1963, poison the rest of her life.

“But that’s not what happened,” Jack said, surprised. He said she had gone on after Dallas and she had even thrived. “But I never got over it,” Jackie said, sadly. “I got past it maybe, but never over it.” “What a shame,“ she now told Jack, “to spend so much time tormented by a thing I could never change.” Then again, Jackie mused, maybe that’s what her husband deserved—for her to never really get over it.

Jack remembered, “I told her I never stopped loving her. I thought she was going to say the same to me. Instead, she said, ‘That’s such a lovely thing to say, Jack. Thank you. I’d like to just leave it there if I may.’” They promised to talk again soon. They never did.

Excerpted from Jackie: Public, Private, Secret. Copyright © 2023 by J. Randy Taraborrelli, with permission from St. Martin’s Press.