The most reliably documented encounter between Marilyn Monroe and John F. Kennedy took place on May 19, 1962, at a birthday fundraiser held in New York.

After the public event, at a private reception in a townhouse, the photographer Ceil Stoutton captured an image of Monroe standing with the president and his brother, Robert Kennedy.

It remains the only known photograph of the three of them together, and it was not widely published until decades later.

Nearly everything else that has been written or said about the relationship between the actress and the president rests on the recollections of other people, most of it recorded fifteen to twenty-five years after the events it describes.

Before that evening in 1962, the two had lived separate lives that began nine years and a continent apart. John Fitzgerald Kennedy was born on May 29, 1917, in Brooklyn, Massachusetts, the second of nine children of Joseph P. Kennedy and Rose Fitzgerald Kennedy.

His was a household full of siblings, expectations, and competition, with summers spent at Hyannis Port on Cape Cod, where the family gathered on the lawns above the water.

His father, a man of considerable ambition, was already thinking about what his sons might become. On June 1, 1926, a girl was born at Los Angeles General Hospital, a charity hospital where the city’s poor patients were treated.

Her birth was recorded under the surname Mortenson, and she was baptized Norma Jean Baker. A third surname, the one the world would later know, had not yet been chosen for her.

Her mother, Gladys Pearl Baker, worked as a film cutter at a Hollywood laboratory, splicing and trimming the negatives of pictures that other people would star in. Who her father was cannot be stated with certainty from the surviving records, and no later account has settled the question.

Gladys could not keep the child with her.

From infancy until she was about seven, Norma Jean lived in Hawthorne, south of the film studios, with a foster family, Albert and Ida Bolender, in a household that was the only stable one she knew in those years.

She lived for a short time with her mother afterward, but Gladys was then hospitalized with mental illness and remained in and out of institutional care for much of the rest of her life.

A friend of Gladys’s, Grace McKee, who later became Grace Goddard, took on the role of guardian.

Kennedy’s childhood moved in a very different direction.

He attended Choate, the boarding school in Connecticut, and then Harvard, where he graduated in 1940. By then his father had spent two years in London as the American ambassador, from 1938 to 1940, and the son had seen at close range a Europe moving toward war.

His senior thesis on British unpreparedness was published as a book, “Why England Slept,” so that a young man of twenty-three had become an author before he had held any office at all.

For the girl in Los Angeles, the next stage had none of that shelter.

From 1935 until 1937, almost two years, she lived in the Los Angeles Orphans Home on El Centro Avenue in Hollywood, only a short distance from the studios where her mother had worked.

She left it for a series of foster homes and the houses of relatives, moving from one arrangement to the next as circumstances allowed.

Grace Goddard remained the guardian of record through these years, though the household she could offer was not always available.

War changed the course of both lives. Kennedy joined the Navy and commanded a patrol torpedo boat, PT-109, in the Solomon Islands.

In August 1943, a Japanese destroyer, the Amagiri, rammed the boat and sank it, and the survivors were left in the water with the wreckage of the vessel behind them.

Kennedy led them to a nearby island. The episode became the foundation of his public reputation, retold in newspapers and later in campaign literature, and it was one of the first things most Americans learned about him.

In the same war years, Norma Jean’s life took an ordinary domestic turn that would not last.

On June 19, 1942, when she was sixteen, she married James Dougherty, the twenty-one-year-old son of a neighbor.

Dougherty soon joined the merchant marine, and she went to work at the Radioplane Company plant in Van Nuys, where the factory floor was given over to the war effort and women worked on the assembly lines of military aircraft.

In 1944 and 1945, a photographer with the Army’s First Motion Picture Unit, David Conover, visited the plant to take pictures of women workers for a morale piece.

He photographed her among them, and those photographs were the beginning of her modeling career.

By then the war had also reached the Kennedy household.

Joseph Kennedy Jr., the eldest son and the one their father had marked out for public life, was killed in August 1944 on a bombing mission. The place he had been expected to fill fell to his brother.

When a seat in the House of Representatives from Massachusetts opened in 1946, John Kennedy ran for it. He was twenty-nine, a war hero with a published book and a surname that carried weight in the state, and he won.

The modeling work led further. Norma Jean signed with the Blue Book Model Agency, and her hair was lightened, a change that altered how photographers and in time the public saw her.

Her marriage to Dougherty ended in divorce in 1946, four years after it began. In August of that year she signed a short contract with 20th Century Fox, and it was there at the studio that the name Marilyn Monroe was chosen for her.

Monroe had been her mother’s maiden name.

So the girl born as Mortenson, baptized as Baker, and now renamed for a studio’s purposes entered the film business in the same year that a young lieutenant returned from the Pacific to win his first election.

He would take a seat in Washington, and she would be sent to the wardrobe and makeup departments of a Hollywood lot. Neither of them yet had any reason to expect that the other’s name would ever appear beside their own.

The first years at Fox did not go as the contract had suggested they might. In 1947 the studio let her go, and the young woman with a new name and lightened hair found herself outside the gates.

She spent the following months looking for work, and in 1948 she appeared in “Ladies of the Chorus” for Columbia, a small picture in which she had a part of some size but which did little to change her prospects.

It was a period of short engagements and uncertain money, and it lasted longer than anything in her earlier modeling years had led her to expect.

The turn came in 1950, and it came through roles that were small but noticed.

In “The Asphalt Jungle,” directed by John Huston, and in “All About Eve,” she appeared in only a few scenes, yet critics and audiences remembered her, and the studio that had dismissed her three years earlier offered her a new contract, this time for seven years.

A calendar photograph then changed the terms of her public life.

In 1952 it emerged that she had posed for the photographer Tom Kelley in 1949, when she needed the money, and the image was now hanging in shops and garages around the country. Fox had reason to fear the story, and reporters waited for her reaction.

She acknowledged the photograph without evasion, and her popularity grew rather than shrank. In 1953 the studio released three films in which she had leading parts.

“Niagara” was followed by “Gentlemen Prefer Blondes,” in which she appeared with Jane Russell, and by “How to Marry a Millionaire.”

In June of that year she and Russell pressed their hands and feet into the cement in the forecourt of Grauman’s Chinese Theater, and the slabs remained there for the tourists who came after.

The girl who had spent two years in an orphanage in Hollywood was now, by any measure of ticket sales, one of the most recognized faces in the country. Kennedy, meanwhile, had been making his way through the Massachusetts political machinery. In 1952 he was elected to the Senate, and he took his seat in January 1953.

What followed for both of them is where documented history and popular memory diverge most sharply.

Kennedy married Jacqueline Bouvier in September 1953 and went on to win the presidency in 1960.

Monroe’s career continued through celebrated performances and well-publicized difficulties, and she died in August 1962, a little under three months after the birthday fundraiser in New York.

Claims of a closer personal relationship between the actress and the president have circulated for decades in biographies, interviews, and films, but they rest almost entirely on secondhand accounts, often recorded long after the fact and sometimes contradictory.

The single photograph taken that May evening, showing Monroe with John and Robert Kennedy, remains the most concrete piece of evidence the public record offers.

Beyond it, the story belongs less to history than to the enduring American fascination with two of the twentieth century’s most famous figures, whose lives briefly and memorably intersected at one documented moment in 1962.