Amanda Knox made an emotional speech upon her arrival in the US last night.

Knox, who was acquitted of the murder of British student Meredith Kercher earlier this week, is back in her home country for the first time in four years.

She told reporters that she was "really overwhelmed" to be home. Knox has spent the past four years in prison in Italy.

Amanda Knox flies home, cleared of Meredith Kercher murder

Amanda Knox: "I want justice for Meredith Kercher"

She told the assembled press at Seattle’s Tacoma international airport: “I was looking down from the aeroplane and it seemed like everything wasn’t real.

“What’s so important for me to say is just thank you, for everyone who’s believed in me, who’s defended me, who’s supported my family.”

She added: “My family’s the most important thing to me right now, and I just want to go be with them."

However, Knox's dramatic acquittal may not mark the end of the case, which has sparked a media frenzy.

Prosecutor Giuliano Mignini has said he will appeal the verdict, which he called "an absolute contradiction" after the jury found Knox guilty of defaming Patrick Lumumba – the man she initially fingered for the murder – but innocent of all other charges.

Mignini added: "Let's wait and see who's right, the first court or the appeal court. This trial was held under unacceptable media pressure. The decision was practically pre-cooked. This is not normal."

In 2009 Mignini secured two murder convictions that jailed Knox for 26 years and her former boyfriend Raffaele Sollecito for 25. However, the prosecution's case was undermined in the appeal court owing to an independent review of flawed DNA evidence.

A lawyer for the only person now convicted for the murder of Kercher, Rudy Guede, said that he would be pursuing a retrial.

The family of the murder victim – who was found stripped semi-naked with her throat cut in 2007 – said the decision left them with many unanswered questions.

Kercher's brother Lyle said: "If those two are not the guilty parties, then who are the guilty people?"