PERUGIA, Italy - A judge ruled Friday there was enough evidence to hold a UW student from Seattle, her Italian boyfriend and a Congolese bar owner as suspects in the death of the girl's British roommate.

In the ruling, the judge said the weapon used to kill the girl was owned by the UW student's boyfriend and his footprint was inside the room.

Amanda Marie Knox, 20, Raffaele Sollecito, 24, and Diya "Patrick" Lumumba, 38, have been detained in the sexual assault and killing of Meredith Kercher, 21, who was found dead Nov. 2.

The Italian press has reported that police found Knox's fingerprints on Kercher's face, suggesting she may have held the victim down during the assault.

Judge Claudia Matteini said there were "serious indications of guilt" that warranted keeping the three in jail for up to a year while the investigation continues. She also warned in a 19-page ruling that each of the three posed a flight risk.

The three, all under investigation for murder and sexual assault, have denied involvement in the killing, according to their lawyers.

Under Italian law, suspects can be kept behind bars without being charged if a judge rules there is enough evidence to jail them and there is a chance they might flee, repeat the crime or tamper with evidence. Prosecutors may later seek to indict the suspects and put them on trial.

The judge said in her ruling that, if released, the suspects could try to leave Italy.

"They could easily have left the territory of the state to escape the investigation," the judge wrote, noting that Lumumba is from Congo, Knox is American and Sollecito could have enlisted his girlfriend's help to flee.

Judge: Murder weapon owned by UW student's boyfriend

Matteini said it was not yet clear who might have dealt the fatal blow, but said Sollecito's footprints were found in Kercher's room, and identified the murder weapon as a knife with an 8.5-centimeter-long (3.3-inch-long) blade that the Italian usually had with him.

However, the judge wrote that, when questioned by investigators, Knox said Lumumba was also in the room and that he had killed Kercher.

In her reconstruction of the incident, the judge said Knox, who worked for Lumumba at his Perugia bar, let the two men into the apartment with her keys.

"Then something went wrong," Matteini wrote. "The two (men) demanded some kind of sexual act, which (Kercher) refused to do. She was then threatened with a knife, which Sollecito always carried with him, and with which Meredith was stabbed in the neck."

The judge later released more information, writing Kercher's screams were so loud Knox covered her ears. The judge also said Knox was confused about the events because she had smoked hashish.

One of Sollecito's attorneys, Luca Maori, said he planned to appeal the decision.

"We didn't expect it," he said. While saying he had not yet read the ruling, he said the defense team was "perplexed" by the judge's decision.

UW student posted disturbing story about raping a woman

Knox's MySpace page has also become a point of interest for authorities and European media, where there is a story about drugging and raping a young woman. But Knox's friends in Seattle say it's just creative writing and are asking people not to jump to conclusions.

Knox is a Seattle Prep graduate, the daughter of a teacher, and a star soccer player. She spent the fall attending the University for Foreigners in Perugia.

Knox's family, who has flown to Italy to be with her, released a statement saying, "We love our daughter very much and certainly stand by her through this ordeal. We know she is probably frightened and upset about what has happened, and needs all the support her family can give her."