She has maintained a private profile since 1977, following her conviction for negligent homicide in connection with the shooting death of her boyfriend, former Olympic skier Spider Sabich.

Many of her acting roles during the 1960s were in episodes of TV adventure series that included Twelve O'Clock High, Combat!, The Name of the Game, The Rat Patrol, Hogan's Heroes, and Alias Smith and Jones.

Longet was cast as Sharhri Javid in the 1965 episode "The Silent Dissuaders" of the NBC education drama series, Mr. Novak, starring James Franciscus.

Williams described Longet as "a beautiful, athletic, slender, petite brunette with large doe eyes--my favorite French singer.

In the episode "The Sadness of a Happy Time", she performed her English-French bilingual rendition of Antônio Carlos Jobim's bossa nova song "Meditation" ("Meditação").

In 1968, Longet co-starred with Peter Sellers in The Party, a box-office hit that Blake Edwards wrote, produced, and directed.

Her charting singles include her version of "Here, There and Everywhere" (music and lyrics by John Lennon and Paul McCartney), "Hello, Hello" (composed by Terry MacNeil and Peter Kraemer), "Good Day Sunshine" (composed by John Lennon and Paul McCartney), "Small Talk" (music and lyrics by Garry Bonner and Alan Gordon), and "Love is Blue", a 1967 Eurovision Song Contest entry that gained fourth place (music by André Popp and French lyrics by Pierre Cour).

Longet and Williams met in Las Vegas in 1960 while she was dancing lead in the Folies Bergère revue at the Tropicana Resort & Casino.

According to Williams, Robert Kennedy told them that he would make a hand signal at the conclusion of his televised speech at the Ambassador Hotel to confirm their get-together.

Longet and Williams eventually joined Kennedy's family and friends at Good Samaritan Hospital, where doctors labored to save the senator's life.

The front page of the 9 June 1968 edition of the Washington Post featured a large photograph of Ted Kennedy and Longet standing together on the rear platform as the train passed through North Philadelphia.

[11] Longet was arrested and charged with fatally shooting her boyfriend, Olympic skier Vladimir "Spider" Sabich, at his home in Aspen, Colorado, on 21 March 1976.

According to prosecutors, the sample showed the presence of cocaine in her blood, and her diary reportedly contradicted her claim that her relationship with Sabich had not soured.

[14] As they were unable to cite any of the disallowed material, prosecutors used the autopsy report to suggest that when Sabich was shot, he was bent over, facing away, and at least 1.80 m (5'11") from Longet, which would be inconsistent with the position and relative distance of someone who is demonstrating the operation of a firearm.

Critical reaction to the verdict and sentencing was exacerbated when she subsequently vacationed with her defense attorney, Ronald D. Austin, who was married then.