Mimi Alford was all of 19 when she began working in the White House press office, and almost immediately caught the eye of President John F. Kennedy

She was a wide-eyed White House intern just four days into the job when she found herself standing alone next to the most powerful man in the world — in the most intimate room within 1600 Pennsylvania Ave.

Mimi Alford (née Beardsley) was all of 19 when she began working in the White House press office in 1962, and almost immediately caught the eye of President John F. Kennedy. While last year’s Jackie movie shed new light on how the first lady created the myth of Camelot after JFK’s assassination, much curiosity remains about their marriage and what Jackie knew.

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As Alford details in her 2012 book, Once Upon a Secret, she was stunned when she received a call from Dave Powers, a close Kennedy aide known unofficially as the First Friend, who invited her for a swim in the White House pool. (It didn’t matter that she didn’t have a swim suit, there were plenty available to choose from.)

Bewildered after diving into the pool with two other young, female colleagues, Alford was nearly dumbstruck when the commander in chief himself walked in a short time later.

“Mind if I join you,” the president purred before heading into the dressing room, emerging a short time later in his swim trunks.

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President Kennedy surrounded by admirers in Santa Monica, California

“He was remarkably fit — flat stomach, toned arms — for a forty-five year old man,” Alford writes, and details how the two exchanged pleasantries while treading water.

Later that same day, Alford was back at her desk when Powers called again, this time wondering if she would be interested in an informal get-together “upstairs.”

She accepted the invitation, and was stunned to discover that “upstairs” meant the family residence — and she soon found herself sipping daiquiris with an intimate group before the president entered the room.

A short time later Kennedy offered her a private tour of the residence, and it was when they were alone in the bedroom he shared with First Lady Jacqueline Kennedy that he made his move.

“This is a very private room,” Alford writes that he told her after slipping a hand on her shoulder.

“The next thing I knew he was standing in front of me, his face inches away,” she writes. “He placed both hands on my shoulders and guided me toward the edge of the bed.”

A short time later, Alford lost her virginity to the world-renowned leader, and their trysts continued for more than a year.

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“I think he did take advantage — I was so young,” Alford told PEOPLE in 2012 of that first intimate encounter. “But I liked feeling special.”

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Although Alford faced criticism for revealing so many personal details in the book — she also wrote that JFK asked her to give Powers, and later his brother Teddy, sexual favors — Alford told PEOPLE in 2012 she has no regrets.