The wrong police were put on the case
The entire murder investigation might've gone differently if the correct cops had arrived on the scene. Instead, Knox and Sollecito encountered the state's so-called postal police, which is normally assigned to petty crimes like phone theft.
Accordingly, two officers were already in the area responding to a call about an abandoned cell phone, which it turned out belonged to Kercher. Knox and Sollecito claim they had already called the carabinieri when the postal police arrived to return Kercher's phone. The postal police claim that call was made later. Regardless, Knox let them into the house to investigate.
As Rolling Stone noted, the carabinieri surely would've closed off the crime scene immediately and conducted a careful inspection. Instead, the postal police let Knox, Sollecito, Romanelli, and Romanelli's three companions "tramp" through the house. They also initially refused to break down Kercher's door, prioritizing her privacy over her safety.
The chief forensics expert would not take Kercher's body temperature, a crucial test for determining time of death, until a full day after her body was discovered. As a result, the tests came back with a wide range of "sometime between 8pm and 4am." A narrower time frame could have cleared Knox and Sollecito, as they were both seen at Sollecito's apartment around 8:45pm, and his computer showed activity until 9:10pm.
One of the prosecution's key pieces of evidence -- Kercher's bra clasp, which contained trace amounts of Sollecito's DNA -- was not bagged for 46 days after the murder. In that time, it had been moved and dumped into a pile of debris. The other major piece of evidence was a knife, which came back with traces of Knox's DNA on the handle and Kercher's DNA on the blade. But when the knife was tested again, none of Kercher's DNA was found.
Knox has always maintained that her signed confession was coerced by the police, who refused to let her see a lawyer and hit her until she agreed to their version of the events. By her account, the police first bullied Sollecito into claiming Knox slipped out of his apartment the night of Kercher's murder. Then they pressured Knox into admitting she had gone back to her home that night, along with her boss at the local bar Le Chic, Diya "Patrick" Lumumba, and heard Kercher scream as he stabbed her.
Whatever happened in that interrogation room, it's clear the police didn't like her; one officer insisted Knox was lying about taking a shower on the morning Kercher's body was discovered because she "smelled like sex."
Tabloids trashed Knox
That "smelled like sex" line very much encapsulates the media's portrayal of Knox as a kinky seductress who killed for sport. This perception was largely shaped by Nick Pisa, the Daily Mail reporter who gave her the inescapable nickname "Foxy Knoxy." Pisa also published Knox's leaked prison diaries. With those, he pounced on details like her worries over an STD scare and previous boyfriends (in his words, "many lovers"). Pisa's reports come across as downright gleeful, and even today, he seems proud of his opportunistic coverage.
Pisa was far from the only one giving Knox a hard time. Over the course of the trials, she was called a "Bambi-eyed killer," "Luciferina with the face of an angel," and a "sex-mad American party girl." And that was just the press -- some of the most vicious nicknames came from the prosecutor trying Knox, Giuliano Mignini. He was fond of calling her a "she-devil," since he was convinced she was in cahoots with Satan.