PERUGIA, Italy (CNN) -- Amanda Knox has told police she's not sure what happened the night her roommate was killed in the Italian villa they shared -- but that she did not kill Meredith Kercher.
Knox, who is still in custody, wrote a four-page statement for police the day she was questioned about Kercher's death, saying she was confused about the events of that night, but wanted "to tell the truth as best I can."
Authorities said Knox, 20, who is from Seattle, Washington, has given investigators at least three different stories about what happened on November 1, when police say 21-year-old Kercher, an exchange student from Britain, was killed.
Kercher's body was found the next day, half-naked, with a stab wound to her neck.
Knox wrote in her statement, a copy of which has been obtained by CNN, that she's not sure whether she was at the villa that night and that she remembers "flashes of blurred images," but doesn't know if they are reality or dreams.
Knox said she believes she spent the night at the home of her boyfriend, 23-year-old Raffaele Sollecito, who is also in custody in the case.
She said she and Sollecito smoked marijuana at his home and watched a movie. She also said she got a message from her boss, bar owner Diya "Patrick" Lumumba, telling her she didn't need to work that night. She says she told Sollecito she could remain at his home all night.
Lumumba was also arrested in connection with the case but later released due to lack of evidence.
In her statement, Knox said she saw Lumumba in "flashes of blurred images."
"I saw him near the basketball court. I saw him at my front door. I saw myself cowering in the kitchen with my hands over my ears because in my head I could hear Meredith screaming," she wrote.
"But I've said this many times so as to make myself clear: These things seem unreal to me, like a dream, and I am unsure if they are real things that happened or are just dreams my head has made to try to answer the questions in my head and the questions I am being asked.
"But the truth is, I am unsure about the truth."
She cites what the police have said is evidence against her, including what she said was hard evidence that she was at the villa she shared with Kercher and two Italians on the night of the slaying.
"I don't know what proof they are talking about, but if this is true, it means I am very confused and my dreams must be real."
"I know I didn't kill Meredith. That's all I know for sure," Knox wrote. "In these flashbacks that I'm having, I see Patrik [sic] as the murderer, but the way the truth feels in my mind, there is no way for me to have known because I don't remember FOR SURE if I was at my house that night."
Knox also writes about Sollecito telling authorities she asked him to lie for her.
"I also NEVER asked him to lie for me. This is absolutely a lie.
"What I don't understand is why Raffaele, who has always been so caring and gentle with me, would lie about this. What does he have to hide? I don't think he killed Meredith, but I do think he is scared, like me. He walked into a situation that he has never had to be in, and perhaps he is trying to find a way out by disassociating himself with me."
Authorities found a knife in Sollecito's kitchen with Kercher's DNA on it as well as Knox's. Police discovered that the knife had been washed, authorities said, but in-depth testing was able to recover the DNA.
Knox said the changes in her stories were due to shock and stress, as well as being hit by police.
"In regards to this 'confession' that I made last night, I want to make clear that I'm very doubtful of the verity of my statements because they were made under the pressures of stress, shock and extreme exhaustion," she wrote. "Not only was I told I would be arrested and put in jail for 30 years, but I was also hit in the head when I didn't remember a fact correctly.
"I understand that the police are under a lot of stress, so I understand the treatment I received. However, it was under this pressure and after many hours of confusion that my mind came up with these answers."