A tearful Amanda Knox paid tribute to her supporters as she arrived home, after being acquitted of murder and sexual assault and ending a four-year ordeal behind bars in Italy.

Fighting back tears, the US student said it felt unreal to be back in her hometown of Seattle.

“I’m really overwhelmed right now. I was looking down from the airplane and it seemed like everything wasn’t real,” Ms Knox said as she addressed supporters and a media scrum at Seattle airport shortly after her plane landed.

“What’s important for me to say is just thank you to everyone who’s believed in me, who’s defended me, who has supported my family,” she said in her first public comments since being freed, brushing away tears.

“My family’s the most important thing to me right now. I just want to go be with them. So thank you for being there for me.”

Her parents, Kurt Knox and Etta Mellas, also offered their thanks, as they accompanied their daughter off the plane and back home.

Lawyer Theodore Simon said the 24-year-old had been through “a trying and gruelling four-year nightmarish marathon that no child or parent should have to endure.”

The family has said little about her immediate plans – reports suggest she will try to lie low in Seattle and take time to readjust to normal life, despite the huge media interest here. Experts say she could earn millions of dollars in book, TV or film rights for the story of her ordeal.

“Amanda Knox is going to be big, because she is so young and she’s so all-American looking, and we go by how things look,” said Charlotte Gusay, a Los Angeles literary agent.

Ms Knox left Rome swiftly after the decision was handed down by an Italian court, first heading for London to board a connecting flight to Seattle on the US west coast.

She had been convicted along with two others and sentenced to 26 years in prison for taking part in the murder and sexual assault of her British housemate Meredith Kercher, then 21, who was found stabbed to death in the cottage they shared.