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She grins and chats and on Valentine's Day sported a T-shirt that read "All You Need Is Love." One of the first things she said in court was about a rabbit shaped sex toy.

Amanda Knox faces life in prison if convicted of killing Meredith Kercher, a British exchange student who was her roommate in picturesque Perugia in central Italy. However, her breezy behavior in hearings over the last three months has set tongues wagging in Italy and abroad.

Knox's family insists she has always been respectful in court and knows full well the weight of the charges against her.

The 21-year-old former University of Washington student is being tried with her ex-boyfriend Raffaele Sollecito for the 2007 killing that mesmerized Italy with its tales of sex and drugs. Both deny wrongdoing.

Knox was in an exchange program in Perugia and sharing an apartment with Kercher, a 21-year-old student from Leeds University in England, when the Briton was found stabbed to death in the house on Nov. 2, 2007.

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Prosecutors allege that Kercher was killed during what began as a sex game, with Sollecito holding her by the shoulders from behind while Knox touched her with the point of a knife.

They say a third man, Ivory Coast national Rudy Hermann Guede, tried to sexually assault Kercher and then Knox fatally stabbed her in the throat. Guede was convicted of murder in a separate trial last year and sentenced to 30 years in prison.

The case, and particularly Knox's alleged role, has made headlines in Italy and abroad and media outlets still converge here for hearings held most Fridays and Saturdays.

Photo and TV coverage of the trial has focused on Knox's calm demeanor, her chats with the interpreter during breaks and in one case even her fashion sense, when she wore a bright T-shirt with "All You Need Is Love" scrawled in large pink letters on Valentine's Day.

In contrast, co-defendant Sollecito, 25, has appeared more tense and kept a lower-profile; he faces the cameras only when briefly waving to his family sitting in front of them.

Italian and European reports have buzzed with remarks.

"She is defiant and he, fearful," summarized Italy's respected daily Corriere della Sera the day after the opening hearing.

"The Foxy Knoxy show: Smiling murder suspect makes grand entrance as trial begins," read a title on the online version of Britain's Daily Mail, which also described Knox as walking "like a Hollywood diva sashaying along the red carpet."

Knox's behavior also raised eyebrows before the trial opened, with a witness recently testifying in court that the American turned cartwheels and did splits at the police station in the hours that followed the murder.

Other witnesses have told the court that Knox made faces at Sollecito at the police station, crossing her eyes and sticking her tongue out, while also giggling and kissing him.

"Her behavior has never been adequate, given the seriousness of what happened," lawyer Francesco Maresca, who represents Kercher's family, said Wednesday. "I criticize a superficial and inappropriate behavior. There's a girl who died brutally, we could use some respect."

However, criminologist Saverio Fortunato says Knox's apparently carefree behavior could be a psychological "reaction to the pain" of being involved in a murder case.

"It could be a sign of malaise and confusion," Fortunato said. "Facing the wounds of a trial can push you to adopt a certain behavior to fight off the fear, which can be interpreted from the outside as inappropriate."

In recent addresses to the court, Knox spoke in Italian and sounded confident, even in her first public statement when she casually explained the presence of a pink rabbit-shaped vibrator in her Perugia house, saying it was "a joke" and a present from a friend.

In a statement e-mailed to The Associated Press, Knox's family described the American as "generally a positive person," who tries to "see something positive in everybody and every situation."

"When she comes to the courtroom, she is generally happy to see familiar faces," the statement said. "The media seems more interested in what she's wearing or how she acts for brief moments ... than in the lack of evidence against her or her respectful, attentive manner during the court proceedings."

Indeed, both Knox and Sollecito sit quietly near their lawyers and follow proceedings intently, taking notes and referencing in Italian law books. Two prison guards are stationed behind them at all times.

The two defendants have largely ignored each other since the trial opened Jan. 16, but recently they exchanged smiles, whispers and gestured from a distance.

Prosecutors say Knox's DNA was on the handle of a knife found at Sollecito's house that might have been used in the slaying and the victim's DNA was found on the blade.

It's not clear how, if at all, Knox's behavior will influence the eight-member jury, which is expected to reach a verdict after the summer.

"Juries can be influenced by the media, but there is also the presiding judge," who as an expert should be able to see through a defendant's behavior in court, Fortunato said. "I don't think that the trial should revolve around this frivolity."

Yet Knox's attitude has made an impression on the public.

"She probably is not even aware of the seriousness of what has happened," said Valentina Discepoli, a 26-year-old law student in Perugia who has attended some of the hearings. "She could be guilty, but her behavior doesn't label her as such."