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.
Prosecutors allege the then 19-year-old punched Ms Ban repeatedly in the head, leaving her face so swollen her gender wasn't immediately obvious to police and paramedics attending the scene.
The court earlier heard forensic evidence she was dragged feet first up a flight of concrete stairs leading from Albert Street to Wickham Park and dumped next to a tree where she drowned in her own blood.
Photos were shown to the court of items on the ground at the Albert Street site, including a smartphone and smashed prescription glasses.
There was also a square of blue fabric which looked like the pocket of a business shirt.
A blue business shirt missing its pocket was found under Ms Ban's body.
Earlier the court was shown CCTV footage from the morning in question, showing a man running shirtless into an address at Spring Hill.
McEwan's colleagues have also testified that he showed up to work at a panelbeaters in Brisbane's west Monday, November 25, 2013 claiming bandages on his hand were for injuries he'd sustained during a fight at a skate park.
The trial is on Thursday expected to hear the police interview of McEwan following his arrest, along with more scientific and forensic evidence.
