It was hard not to notice Amanda Knox as she entered an Italian court for the final time earlier this week — a young, striking American woman walking slowly into a room packed with justice officials, police and reporters from around the world awaiting the verdict from the appellate judge who would set her free just moments later.

The 24-year-old from Seattle was convicted four years ago, along with her former boyfriend, Raffaele Sollecito, of murdering her 21-year-old British roommate, Meredith Kercher, following what prosecutors described as a drug-fuelled sexual assault. The case became an international sensation, generating headlines around the world portraying Knox as everything from a naive girl out of her depths to a beautiful, seductive, manipulative killer the tabloids quickly dubbed "Foxy Knoxy."

After reviews ordered by Italian courts discredited DNA evidence and destroyed the prosecution's case against Knox and Sollecito, an appeals court overturned their convictions on Monday and ordered the pair be freed.

For Georgie Ann Weatherby, a criminologist and professor of sociology and criminal justice at Gonzaga University in Washington State, Knox's case, as well as the recent trial of Casey Anthony, who was acquitted of the murder of her two-year-old daughter, who died three years ago in Florida, dovetailed into her continuing research on women accused of violent crimes and how they are portrayed, perceived and sentenced.

Weatherby saw that despite the seriousness of the accusations against them, the two women, especially Knox, could be construed as victims of the system, perceived as sweetly feminine — and therefore, incapable, at least in the eyes of a jury or a judge, of the horrors described in each crime.

Weatherby has researched the cases and trials of notorious female killers such as Andrea Yates, Aileen Wuornos and Karla Fae Tucker. Yates, a Houston housewife who confessed to drowning her five young children in 2001, was convicted of capital murder, but was later found not guilty by reason of insanity at a second trial and remains institutionalized.

Wuornos, one of America's few known female serial killers, was executed in 2002 for the murders of six men while she was working as a prostitute, despite her claims she shot middle-aged men in self-defence while being raped and sodomized. Her story was made into the Academy Award-winning film Monster.

Tucker was executed in 1998 in Texas for her role in the axe-murders of two people in 1983 while under the influence of drugs and alcohol.

Part of Weatherby's research of the cases focuses on the chivalry theory, a sociological premise that women accused or convicted of violent crimes are often treated leniently because of paternalistic attitudes of authority figures or justice systems toward their gender, as long as they appear to fulfil stereotypical feminine roles.

In an interview with CBC News, Weatherby said the rareness of women being of accused of violent crimes often fuels the public's fascination with cases like Knox's and Anthony's.

She said friends, legal scholars, students she's talked to about the cases, as well as her husband, expressed doubt over their guilt — not because of Italian investigators' errors, but because of how they looked or behaved.

A: I think it's something more with women charged in violent crimes because it's not very common. We can't understand what the heck's going on with it.

A: We need to watch it and figure out why this is happening. To us, these women have either overstepped their bounds or they're not guilty.

A: When it's not clear, they basically will give the woman the benefit of the doubt, unless she portrays an anti-feminine image. They do not do that with men.

I said to my husband last night, "I don't know if she is guilty or not in all of this, Amanda Knox, but I know that they botched all of this, and that's what this is about." And he said, "Oh, she's a student in the University of Washington! She could never have done this." My husband, who lives with a criminologist for years on end and reads my research, and he's falling right into the pattern. I'm not sure, but I know when you have a botched system and you have a woman who seems to be typically female in her responses, we just don't think she has the possibility of doing it.

When we thought Karla Fae Tucker was the ringleader in her case, we really wanted her to go to death row. She admitted in her trial that she had an orgasm every time she swung the axe. People hear that and they say, "This is not a woman anymore."

A: It seems that with time there has been a softening in the image of Knox over the course of her imprisonment, and the leaking of information of what she's doing and the fascination with it. My perception was in the beginning, there might have been less sympathy because it was portrayed as such a brutal murder by more than one person. But even in the beginning, as the facts came out, I think the American public is rather astute, even though they're not trained legally. But I think they understand evidence enough because we have a lot of popular shows, CSI and other stuff, that when they start bringing in character and talking about questionable hygiene and things that are absolutely irrelevant in the law, even the lay public would question the motivation behind doing that. And the seemingly sloppy detective work on the part of the Italian justice system, I think that people are very used to the U.S. system. I've polled my students several times, and I think they've come to appreciate our justice system more, despite its flaws, considering the Italian fiasco of how they collect evidence.

Through time … if the accused defendant on trial, especially if its a woman, is seen as a classic, typical feminine figure, she's almost seen by the public as incapable of such a crime. If she's someone like Aileen Wuornos — a prostitute, hates men, and acts that way in court — then sympathy is lacking. I think people basically had to get their bearings with Knox. They also did the same thing with Casey Anthony.

A: Well, I was unable to watch most of the trial because I was teaching and researching, but what I saw of it and read and spoke to people, in a kind of a straw poll, I observed how they started to see Casey Anthony as a victim of the system. "Maybe she was wrongly accused and she didn't know how to defend herself." My students this summer, who are all pretty astute and were all female, were saying, "Oh, she's so pretty, she couldn't have possibly done such a heinous act." They were looking at what she was projecting and emanating as a feminine woman. In terms of chivalry theory, in courts, on the bench and the jury, too, whether the judge is female or male, if the woman is depicted as really feminine and her crime is seen as a heinous, non-feminine crime, then we're likely to go more lightly on her than a man committing a really brutal, violent crime. If she's portrayed and depicted or emanates more masculinity and not the typical image, then we want justice to be more severe because the woman has stepped outside the feminine bubble.

A: Oh yeah. You're totally brutal and we're not. The chivalry theory comes from us, and judges are no different. Jurors are our peers, so they are us. Judges are not above that either.

A: Yes, and men use more violent means. There are data to back this up in terms of sheer numbers.

A: ...us incapable. However, if we cross that line. That's the interesting part of chivalry theory, that people do this without doing it. Karla Fae Tucker is an example of a woman who crossed the line, with axe-murdering. They're not perceived as feminine anymore. To the public, to juries, even to judges sitting on all levels, they see this as most heinous thing of all, to cross that line and leave that femininity behind.

A: Karla Fae Tucker was "bad." Aileen Wuornos was "bad." Andrea Yates was "mad." She's a housewife, she's a June Cleaver-type, vacuuming and wearing pearls. She's well-off, her husband loves her (didn't work out for them so well, but at least at the time.) She couldn't have done that unless she lost her mind, at least temporarily. That's what we think.

A: It's very much a class perception. You have housewives of all levels, but when they're of a privileged class, they're taught to be feminine and know better. So there's all kinds of bias here. Wuornos was not only anti-feminine, but she was lower class. She was everything people don't identify with, or abhor. Our prejudices come out. Who we favour. Who gets a better trial? Someone who couldn't afford it? Probably not.