LOS ANGELES (AFP) - Amanda Knox may return to Italy to be re-tried for murder, she said on Tuesday as she launched a memoir about her case, including frank details about sex, drugs and her harrowing time behind bars.

In interviews to promote the book, which recounts how she considered suicide in jail, she said she hoped her slain former roommate Meredith Kercher's family would read it, although she has not had any contact with them.

"It matters to me what Meredith's family thinks... I really hope that the Kerchers read my book. And they don't have to believe me. I have no right to demand anything of anyone. But I hope they try," she told USA Today.

Ms Knox, 25, was ordered to stand trial again by Italian authorities last month in the latest twist of the legal saga, which had seen her acquitted on appeal in 2011 following her earlier conviction.

The American student and her former Italian boyfriend Raffaele Sollecito had originally been sentenced to 26 years and 25 years in prison for the killing of Kercher six years ago, allegedly in a drug-fuelled sex attack.

Although legal analysts expect Ms Knox to be tried again in absentia following the decision in March to order a new trial, the former student told USA Today in an interview she was "considering" returning to Italy.

"My lawyers have said that I don't have to and that I don't need to. I'm still considering it, to be honest," she was quoted as saying when asked if she planned to return to Italy.

"It's scary, the thought. But it's also important for me to say, 'This is not just happening far away from and doesn't matter to me.' "So, somehow, I feel it's important for me to convey that. And if my presence is what is necessary to convey that, then I'll go." Ms Knox is currently launching a publicity blitz in the United States to promote her autobiography Waiting To Be Heard for which she was reportedly paid a US$3.8 million (S$4.7 million) advance.

In the 480-page book, she describes her early life in Seattle and her decision to take a year out to live in the small Italian city of Perugia to learn Italian language and culture.

She is open about her attitude to sex, and how it was changing as she headed overseas. She had had sex with four men before her departure.

"I left for Italy having decided I needed to change that. For me, sex was emotional, and I didn't want it to be anymore.

"I hated feeling dependent on anyone else. I wanted sex to be about empowerment and pleasure, not about 'Does this person like me? Will he still like me tomorrow?'," she said.

She moved in with two Italian girls and Kercher, who was also a foreign student, and led an easy-going life with a group of boys who lived downstairs in the same house.

"Around our house, marijuana was as common as pasta," she wrote, while describing in detail a number of sexual encounters before she met Sollecito, a week before the murder.

She also recounted the day Kercher's body was found, how police rapidly became suspicious. In one early interrogation she reported being slapped around the head while being told "Stop lying!" Ms Knox was eventually charged, tried and sent to jail - where she described repeated sexual harassment and detailed thoughts of suicide, for example in the shower, where "steam would fog up the guard's viewing window."

"I imagined cutting both my wrists and sinking into oblivion in a calm, quiet, hot mist," she writes.

In excerpts of an interview with ABC News anchor Diane Sawyer released ahead of broadcast on Tuesday, Ms Knox said she wanted to clear her name, in terms of her public reputation as well as legally.

"I'd like to be reconsidered as a person," she told ABC. "What happened to me was surreal, but it could've happened to anyone."