Alex Reuben McEwan told police a "demon inside his head" made him brutally bash a Korean woman, drag her up a set of concrete stairs and dump her in a Brisbane park to die, a court has heard.
He has pleaded not guilty to murdering Eunji Ban in the city's centre in the early hours of November 24, 2013, but admits to her manslaughter.
In a recording played to the Brisbane Supreme Court jury on Wednesday, McEwan can be heard telling arresting officers "on the night of the murder" he "just woke up randomly and did it."
"I was kind of waiting for it my whole life," McEwan can be heard telling the officers.
When asked what he was waiting for, he responds: "To kill someone."
His lawyer argues his schizophrenia left him unable to control himself when he killed Ms Ban.
During his trial on Friday, the court heard details of letters McEwan wrote to the 22-year-old's family after he bashed her so severely she drowned in her own blood.
"I can't explain how sorry I am for your loss," McEwan wrote to the woman's grieving relatives.
"I wish I could take it all back and give her a bunch of roses instead. I will be praying for you."
In a letter to his own family, which has also been read to the court, McEwan said he was ashamed of what he had done.
"I'm not sure if I will be able to look you in the face ever again because of what I've done to that innocent lady," he wrote.
He said he was sure he was bewitched by a demon at the time because he could not remember what happened.
"Don't forgive me, don't think of me ever again," he wrote.
