The second conviction of Amanda Knox and Raffaele Sollecito for the murder of British student Meredith Kercher in 2007 has baffled many commentators who were quick to point to the flaws in Italy's judicial system.

Speaking from hometown Seattle, a defiant Knox insisted she would never willingly return to Italy to serve her 28-and-a-half year sentence, saying. "I'm going to fight this until the very end.

"It's not right, and it's not fair and I'm going to do everything that I can," she told ABC News' Good Morning America programme.

Although her sentence or the 25-year prison term handed to Sollecito will not begin until further appeals have been heard, it looks quite likely that the Supreme Court will confirm the ruling.

Six years of legal wrangling since Kercher was killed have failed to clear the air of mystery surrounding the case.

Knox was originally convicted of killing Kercher in 2009 by a court in Italy. The verdict was overturned on appeal in 2011 and Knox and Sollecito were freed, after spending a total of four years behind bars.

Homeless drifter Rudi Guede was convicted of killing Kercher in a separate trial and was jailed for 16 years.

Knox and Sollecito were cleared of murder after doubts were raised about the methods used by police to gather DNA from the crime scene. Heavy criticism was aimed at police for their handling of the murder investigation.

But the Supreme Court ordered a retrial because the appeals ruling was "marked by multiple shortcomings and contradictory and illogical profiles".

The fresh sentence means the appeals court has confirmed that Knox and Sollecito were both on the crime scene and both took part in the murder of Meredith Kercher.

Raffaele Sollecito Talks Meredith Kercher Murder Retrial IBTimes TV

A confused alibi

The most crucial point to take into consideration is Knox's statement after Meredith's death.

The American citizen told police that a black man, Patrick Lumumba, was responsible for the murder. She detailed how Lumumba wanted sexual intercourse with Meredith and that both locked themselves in a room. Knox went on saying that she plugged her ears because she did not want to hear what was happening.

Fiorenza Sarazanini, journalist for Corriere della Sera, reports that Knox "wrote her memorial in some papers that were handed over to police".

The Supreme Court said those statements "couldn't not be dismissed, as they were, on the assumption of psychological pressure" put on Knox.

This thesis has been adopted by Knox for years to justify the remarks in which she accuses Lumumba of the murder.

The Seattle-born woman repeated to the Guardian, ahead of the sentence, that Perugia police "made it seem like I had something wrong with my memory.

"And they kept saying, if you can't remember what you did [... ] then there's something wrong with you and you're lying [...] It made me question my own memory.".

However, prosecutors and judges from the Supreme Court have questioned the reliability of this theory. Knox's written testimony was produced "in solitude" and after the excesses of the investigators.

The American even told the same story, accusing Lumumba to her mother, during a private conversation.

Finally, the written statement was used by the appeals court to condemn Knox for false accusation against Lumumba [an offence known as calunnia under Italian law].

The appeals court ruling means that Knox was trying to cover-up Rudi Guede – and herself – when she unlawfully accused Lumumba of the murder. The Italian justice's mix-up, unfortunately, crippled any attempt to ever find the truth on what happened that night.