By Maurizio Troccoli
PERUGIA, Italy (Reuters) - Lack of motive and faulty evidence led to the acquittal of American student Amanda Knox in the murder of her British flatmate, the Italian court that cleared her said on Thursday.
Knox, 24, saw her previous conviction for the murder of Meredith Kercher overturned by the appeals court in October. Hours later, she left the hill town of Perugia and flew home to Seattle.
Kercher, 21, was murdered in 2007 in the apartment she shared with Knox when they were studying in Perugia. The Briton's half-naked body was found in her own bedroom with over 40 wounds and a deep gash in the throat.
Also acquitted on appeal was Knox's boyfriend at the time of the murder, the Italian Raffaele Sollecito.
A 144-page document issued by the court to explain its reasoning said forensic evidence used to support the original verdicts was unreliable, and could not ultimately prove the couple were at the crime scene on the night of the murder - November 1, 2007.
Ultimately, the prosecutors' case could not stand, the court said.
"The bricks of that building just gave way," the document said. "It's not just a case of reassembling the bricks ... but rather a lack of the necessary material for the construction."
In Italy, courts have to release a document to explain their motivation for reaching a verdict.
The court pointed to what it said were flaws in collecting forensic evidence and testing DNA traces originally linked to the defendants. The two have always denied being at Knox's house at the time of the murder.
Knox, who is now considering deals to write a book about her experience, was originally sentenced to 26 years in prison and Sollecito to 25 years in a case that drew attention around the world.
Rudy Guede, an Ivorian drifter who was found guilty and sentenced to 16 years' jail in a separate trial, is now the only person serving time for the murder, although prosecutors said he could not have killed Kercher by himself.
STABBED IN NECK
The prosecutors said the lack of signs of a struggle on Kercher's body showed that more than one assailant had pinned her down before stabbing her in the neck.
The appeals judges said it was not up to them to decide whether or not Guede acted alone.
They said no motive had been established and there was no indication that Knox or Sollecito had known Guede before the murder.
"The sudden choice of two young people, good and helpful to others, to commit evil for evil's sake, without any further reason, seems even more incomprehensible (if it is) to support the criminal act of a young man they had no relation to," the court said.
It also said there was no proof that the knife discovered in Sollecito's flat, which police identified as the murder weapon, had ever been present at the crime scene.
The grieving family of Kercher, a Leeds University student, said after the acquittal they felt they were "back to square one" and they needed to know who killed their beloved "Mez," as Kercher was known, if Knox and Sollecito were innocent.
Prosecutors have said they will appeal against Knox's acquittal at the Court of Cassation, Italy's highest appeal court, which can only review possible technical errors in lower court cases.
Independent forensic experts told the appeal trial that police had botched the investigation and had failed to secure the crime scene or follow international forensic protocols. DNA evidence could have been contaminated, they said.
(Writing by Catherine Hornby; Editing by Barry Moody and Alessandra Rizzo)