Prosecutors called her conniving and callous. The jury believed them

Depending on who you asked, Amanda Knox was a sex-crazed killer or an innocent abroad. Andrea Vogt weighs up the evidence

Meredith Kercher's battered and semi-naked body was found on the morning of November 2, 2007, lying in a pool of blood in the Perugia flat she shared with three other women, two Italians and one American. The Leeds university exchange student had been stabbed in the neck multiple times.

Over the course of the two-year investigation into her murder, two very different narratives of her American flatmate Amanda Knox emerged: one was the wholesome but naive West Coast American student caught up in a nightmarish tsunami of police, judicial and media blunders. The other, and the narrative the prosecution pushed forcefully, was that of the diabolical, conniving girl who killed her flatmate over petty jealousies and then callously blamed someone else to throw investigators off. Last night it was the prosecution's version of events that the jury decided to believe.

Immediately after the discovery of Miss Kercher's body, police testified that they found Knox and her Italian boyfriend Raffaele Sollecito's behaviour suspicious. But it was the conduct of the young American woman that was deemed especially bizarre. Police immediately began monitoring their mobile phone conversations.

Knox, Sollecito and Rudy Guede, an immigrant drifter from the Ivory Coast, were eventually charged with murder and sexual assault. Over the course of the trial the battle between Knox's defenders and her prosecutors steadily grew more acrimonious, and a sharp international divide over her guilt or innocence opened up. Throughout, Knox's quirky character was fodder for the more salacious end of the Italian media.

What happened in the immediate aftermath of the murder and during the launch of the investigation is still a matter of dispute but may have been key in determining how the prosecution case was constructed. Knox's lawyers say she was questioned by police for more than 50 hours during the first five days after Meredith's death, culminating in a late-night session on 5 November and into the morning of 6 November. Knox claims that Perugia police coerced her under harsh questioning that included cuffs to the back of the head. Police deny she was mistreated.

Either way, the end of this period saw Knox breaking down and claiming she had been in the flat the night of the murder. But she tried to deflect any blame by accusing Patrick Lumumba a Congolese man who owned a bar in Perugia, of being the assassin. Lumumba was jailed for two weeks but subsequently freed and absolved of any connection to the crime when forensic testing incriminated Guede. Knox still faces a civil slander suit as well as criminal charges for falsely accusing Lumumba.

Rudy Guede's DNA and bloody footprints were found all over the room where Kercher's body was found and prosecutors also claim they established that he sexually molested Meredith. He initially fled to Germany but was arrested by Interpol on a train and extradited back to Italy. Guede opted for a "fast track" trial, separate from Knox and Sollecito, his lawyers fearing that the young pair would try to pin the blame on him to save themselves if they were tried together. In any case he was convicted and sentenced to 30 years prison. He is now appealing, claiming he was in the bathroom when a fight broke out between Knox and Kercher. He claims he scuffled with an Italian man, then tried to stop Kercher's bleeding before panicking and fleeing the scene.

But the prosecution had maintained throughout that Guede, Knox and Sollecito acted together, with Sollecito restraining Kercher, Guede sexually molesting her and Knox eventually delivering the fatal stab wound. Prosecutors then say that Knox and Sollecito returned to the scene of the crime to stage a burglary and rape in order to throw investigators off. Knox harboured hate for the "prissy" British roommate who complained about Knox's hygiene and household habits, like keeping condoms and a vibrator in plain sight in the bathroom. The two began arguing about missing rent money, prosecutors argued, and the fight degenerated into an "unstoppable crescendo of violence" that ended when Kercher was stabbed to silence her. Defence lawyers ridiculed the theory as "pure fantasy."

The trial, which began in January 2008, involved 50 hearings. The prosecution called more than 100 witnesses to testify about Knox and Sollecito's odd behaviour and conflicting statements, but they relied heavily on DNA evidence. DNA traces found in the small house Knox shared with Kercher for example identified blood and footprints compatible with the women, prosecutors said.

Specifically, forensic police from Rome testified that five mixed DNA samples – blood or DNA that tested positive for both Kercher and Amanda Knox – were found in various rooms. Defence lawyers countered that Knox's DNA could have been there for ages and that this was not unusual, since she lived in the house. Knox's DNA was found on the handle of the kitchen knife that prosecutors allege was used to stab Kercher, a trace of whose DNA was found on the blade. Defence experts contested much of the evidence, alleging the investigation had been badly bungled with shoddy police and lab work.

The Kercher family – her divorced parents, two brothers and sister – were civil plaintiffs in the trial and backed the prosecution's theory. Kercher's mother, Arline, father, John, and sister, Stephanie, flew to Perugia as witnesses, giving heartbreaking testimony that left jurors in tears.

Seven of Miss Kercher's British friends also testified. At the time of her death, Miss Kercher was studying Italian, political science and history in Perugia under the Erasmus student exchange scheme. She had a promising future ahead of her, her father testified, with aspirations to work as a journalist or in Brussels for the European Union.

But Knox's family and friends also took the stand on her behalf, describing her as a normal all-American girl very different from the depictions of her as a sex-crazed, hate-filled diabolical vixen.

Ultimately, however, the jury took a different view.

Kercher case: The key characters

*Meredith Kercher

The 21-year-old European Studies student from Surrey arrived in Perugia in the autumn term of 2007 for a year out from her degree course under the Erasmus student exchange programme.

*Amanda Knox

Seattle-born Amanda Knox spent two years in prison on remand before being found guilty. Her antics in prison garnered her negative attention: she reportedly performed cartwheels and pulled faces before being questioned by police, practised yoga in her cell, and sang Beatles songs to fellow inmates.

*Raffaele Sollecito

The engineering student and ex-boyfriend of Knox was 23 at the time of Kercher's death. The son of a doctor from Bari, he and Knox met at a concert just a fortnight before the murder of which they were convicted last night.

*Curt Knox and Edda Mellas

Throughout the trial Knox's parents – who are divorced, but worked together to defend their daughter – kept a high profile, giving interviews and making statements to reporters. Not only did they campaign in the US media to clear their daughter's name but they accused the Italian police of brutality.

*John and Arline Kercher

Meredith Kercher's parents last month released a statement on the second anniversary of her death hoping for a speedy conclusion to the trial "so that we can finally dedicate ourselves to remember Meredith for the person that all of us knew and not as a victim or as a news item".

*Giuliano Mignini

The role of prosecutor is a powerful one in the Italian legal system, and Mignini announced within a week of Kercher's death that he had solved the case and alleged that Knox and Sollecito were both guilty of murder.