(ANSA) - Rome, November 20 - A US student accused of the murder of British exchange student Meredith Kercher, hated her ''snobby'' roommate and meant to punish her, prosecutors said Friday while delivering their final arguments.

Amanda Knox, 22, is on trial together with her former Italian boyfriend, Raffaele Sollecito, 26, for stabbing Kercher while forcing her to participate in what prosecutors described as a ''perverse sex game'' in November 2007.

The two then allegedly broke a window in an attempt to simulate a break in.

Recapping the accusations against them, lead prosecutor Giuliano Mignini said that disagreements over money, friends and money led to resentment between the two girls.

He said that the American girl was bent on ''punishing'' her and enlisted the help of Sollecito and Ivory Coast native Rudy Guede. According to the prosecution, Knox and Sollecito met with Guede on the night of Kercher's murder, "possibly for drugs", and then went to the two girls' house where the victim was home alone.

''At that point, there was an argument about money, or perhaps because Meredith wasn't happy about Guede coming over, followed by an attempt to get her involved in some kind of sex game. And that's when her ordeal began,'' said Mignini.

According a the prosecution's reconstruction, Sollecito held Kercher down while Knox held a knife to her throat and Guede tried to sexually assault her, before Knox slit her throat.

Guede was convicted during a separate trial in March and was given a 30-year-sentence, which an appeals court began examining on Thursday.

The prosecution described him as an "unofficial defendant" in the current trial, with both Knox and Sollecitos' legal teams casting him as the "lone killer".

Sollecito's legal team last month presented medical evidence purporting to show that a bloody footprint found in the house was not his, but Guede's.

Guede admits that he was in the house at the time of Kercher's murder, but says he was in the bathroom listening to music, when he heard Knox return home and begin an argument about money.

But Knox maintains that she spent the whole night in Sollecito's house in another part of Perugia, while he claims to have been in front of the computer all night.

Sollecito has said he doesn't remember whether Knox spent the whole night at his house.

Knox's defense team has also suggested that police have the wrong murder weapon. They said the 17-cm inch knife was too long to be compatible with the 8-cm wound found on Kercher's throat The knife was found in Sollecito's house shortly after the murder and police say it has Kercher's DNA on the tip and Knox's on the handle.

Defence lawyers said the DNA was contaminated.

Minigni also reminded the court that Kercher faced charges for wrongly accusing Perugia-based musician Patrick Lumumba, who was later cleared of all involvement in the case.

''She knowingly accused an innocent man of murder, content to let him languish in jail,'' the prosecutor said.

Mignoni also made mention of the "parallel media trial on three continents" which he said had twisted and obscured many of the fact of the case.

''But the only trial that matters, is the one today in this court room,'' he said.

On Saturday, the prosecution will rest its case and ask for a sentence. Judicial sources say a verdict is expected in early December.