Killer screamed 'die, b---h, die' as he beat student to death

A confessed killer screamed "die, b---h, die" when he beat a Korean woman to death as she walked through a Brisbane park, a court has heard.

Alex Reuben McEwan has pleaded not guilty to murdering Eunji Ban in November 2013, but guilty to a lesser offence of manslaughter on mental health grounds.

McEwan's trial in the Brisbane Supreme Court has heard evidence of what he told police during a formal interview after the killing.

He told officers that he'd said to Ban: "It's your fault you walked this way because you had to run into me" as he violently attacked her.

He also told her: "Die, b---h, die" when he strangled, stomped and punched her for what felt to him like "over a thousand times", the court was told.

"I killed her. Stomped her face in with my feet and my fist. Dragged her across the road," he told police.

"Can't believe I did that ... I f---ed up.

"I didn't look at her. I just did it."

Ban didn't scream due to the suddenness of the attack but was begging "no" and for "me not to hurt her", McEwan said.

McEwan's defence lawyer argues his schizophrenia left him unable to control himself when he killed Ban.

"It was a f---ing demon, man," McEwan told police.

"It doesn't feel like me who did it ... feels like I was possessed.

"I felt like I was trying to go kill. This feeling has been troubling me my whole life.

"Felt like the night ... Felt like it was really strong. Really, really strong. Like I was watching a video while it was happening."

Asked by police if he had a mental health diagnosis, he said: "No ... that's the reason why this happened."

He also asked to see a photo of Ban's battered body "for my personal relief", later claiming the request "wasn't for relief. It was to hurt myself".

He said he felt like a "different person" during the killing after leaving his family's inner-Brisbane unit early on November 24, 2013, to go "out to kill".

McEwan said he kept bashing Ban as he dragged her upstairs to Wickham Park, near her Roma Street Parklands unit, because she was making "weird noises".

He said he saw bubbles of blood coming from her face.

Ban, 22, was found by a tree in the park with head injuries so severe she drowned in her own blood, the trial has heard.

She was walking to her cleaning job when she was attacked by McEwan, who was 19 at the time.

He repeatedly apologised and expressed remorse throughout the police interview and in letters to his victim's family and his family.

"I will be praying for you," he wrote to Ban's family.

The trial continues.

With AAP