Amanda Knox's lawyer argued Tuesday there wasn't sufficient evidence to convict the U.S. exchange student in the 2007 slaying of her British roommate, saying Knox had been swept up by a "tsunami" of events that led to her arrest.

In his closing arguments in the year-old trial, defense lawyer Carlo Dalla Vedova charged that key DNA evidence in the case cannot be attributed "beyond any doubt."

SLIDESHOW: Amanda Knox on Trial for Murder

"There are still many doubts in this trial, and there's a young girl waiting to be judged," he told the eight-member jury, which is expected to issue a verdict this week.

The Seattle-born Knox and her former Italian boyfriend Raffaele Sollecito are being tried in Perugia, central Italy, for the 2007 slaying of Meredith Kercher. They deny wrongdoing.

Kercher's body, her throat slit, was found in a pool of blood on Nov. 2, 2007, in the apartment she shared with Knox in Perugia. Prosecutors argued that Knox resented her British roommate and killed her, together with Sollecito and Rudy Hermann Guede of Ivory Coast, under "the fumes of drugs and possibly alcohol."

Prosecutors say a knife with a 6 1/2-inch blade, with Kercher's DNA on the blade and Knox's on the handle, was found at Sollecito's house.

Defense lawyers have argued that the knife is too big to match Kercher's wounds and claim the amount of what prosecutors say is Kercher's DNA is too low to be attributed with certainty.

Dalla Vedova also countered prosecutors' claim of a possible motive for the slaying. Prosecutors have charged Knox wanted to get back at Kercher for saying she wasn't clean and was promiscuous.

"We need facts, not only vague statements," said Dalla Vedova, who contended that any such resentment couldn't explain the crescendo of violence that led to the killing.

The lawyer also portrayed Knox as a "clean-faced young girl, swept away by a tsunami," who decided not to go back to the United States as she could have in the days after the slaying.

Knox, 22, and Sollecito, 25, have been jailed for more than two years since being arrested shortly after the slaying. They are being tried on charges of murder and sexual violence and prosecutors have urged they be given life imprisonment — Italy's stiffest punishment. Both were in court Tuesday.

Guede was sentenced to 30 years in prison last year after a fast-track trial he had requested. He also denies wrongdoing and is appealing his conviction.

Knox and Sollecito maintain they spent the night of the murder at Sollecito's house in Perugia, watching a movie on his computer. Their defense lawyers are working on the theory that Guede was the sole attacker.