Alex Reuben McEwan has admitted killing Eunji Ban near Brisbane's CBD in November 2013.

But he has pleaded not guilty to murder, arguing diminished responsibility on the grounds his mental illness left him unable to control himself.

McEwan has testified being possessed by a demon when he attacked Ms Ban near her Roma Street Parklands unit in the early hours of the morning

He dragged her body up stairs to the nearby Wickham Park before dumping it by a tree.

The Brisbane Supreme Court trial has heard from three psychiatrists who believe McEwan wasn't suffering the affects of schizophrenia at the time of the killing.

"I think this young man has been inconsistent in his accounts of many, many things about the alleged offences," psychiatrist Pamela van de Hoef told the court on Monday.

"To the police, he said it was 'as if' I was watching someone else. 'As if' I were possessed," she said.

"The people I've interviewed, assessed, treated who have had passivity phenomena, there's no 'as if' about it. It actually 'is'. It is perceived as happening that way.

"That (McEwan's) kind of description is much more in keeping with dissociation, de-realisation, depersonalisation."

McEwan, who was diagnosed with schizophrenia after his arrest, told the court he tried but could not prevent himself from attacking Ms Ban.

Closing submissions in the trial will begin on Tuesday morning before the jury is sent out to consider its verdict.

Australian Associated Press