By Deepa Babington

PERUGIA, Italy (Reuters) - Amanda Knox killed her British roommate "for no reason" and the American student and her former boyfriend should face the maximum penalty for their crime, her appeals trial was told on Friday.

Prosecutors urged the court to uphold Knox's sentence for murder and said the 24-year-old would flee Italy if freed.

Knox, jailed for 26 years, and her Italian ex-boyfriend, Raffaele Sollecito, are fighting their convictions for the murder of Briton Meredith Kercher in 2007. A verdict is due on Monday.

Knox and Sollecito should be kept behind bars for life, prosecutors said, and they reminded the jury of the gruesome nature of the crime. Kercher's body was found with more than 40 wounds and her throat slit.

"They were young but they killed for no reason," said prosecutor Manuela Comodi. "They killed for no reason and for this they should be given the maximum sentence, which luckily in Italy is not the death sentence."

If the guilty verdicts are overturned, both would be freed immediately. Speculation has been rife that Knox would be whisked home to the United States, where the death penalty exists, if she is freed from the Umbrian prison where she has been held for nearly four years.

Any subsequent appeal by prosecutors or any re-trial might therefore take place in Knox's absence.

"We know that if the verdict is overturned, there will be an immediate escape overseas," prosecutor Giuliano Mignini told the court in rebuttals after closing arguments.

"As a result, even if this is the second of a three-step legal process in Italy, it is up to you to ensure justice."

Kercher's mother and sister are expected to attend Monday's court session when the verdict is announced. They have kept a low profile since the murder, in stark contrast to the Knox family which has waged a tireless media campaign to free her.

Kercher was on a year-long exchange program in Perugia, a cobble-stoned town popular with foreigners studying Italian, when she was murdered.

Her family's lawyer, Francesco Maresca, has described her as sunny young woman "full of life" who was killed during a brutal assault during which the 21-year-old was held down by her assailants.

Knox and Sollecito, who was jailed for 25 years, deny any role in the murder and say they spent the night of the crime in the Italian's apartment watching a movie, smoking pot and having sex.

Sollecito's father said his son was "very scared. But he is hopeful of the right verdict."

"I am hopeful that the court has heard well the arguments presented in the appeals trial and has realized that there isn't any evidence against my son and Amanda," Francesco Sollecito told Reuters.

Rudy Guede, an Ivorian drifter with a criminal record, is also serving time for taking part in Kercher's murder. He has also maintained his innocence.

(Reporting by Deepa Babington; Editing by Robert Woodward)