"He was probing regularly about the existence of demons," his mother Ruth McEwan said on Friday.

Murder accused asked mum about ‘existence of demons’

MURDER accused Alex Reuben McEwan told his family of disturbing forces troubling him, a jury has heard.

"He was probing regularly about the existence of demons," his mother Ruth McEwan said on Friday.

She said her son described feeling mental anguish before 22-year-old student Eunji Ban was killed.

"He said: I'm not normal. I don't feel right. I can't see properly. I can't see left from right."

Mrs McEwan said her son spoke of "a sphere or a ball rolling round and round in his head, and he couldn't make it stop because it doesn't have any flat sides to stop so it just keeps rattling him over and over."

On Friday, the tearful mother told Brisbane Supreme Court Alex had an "inability to manage his own affairs".

She said her son at school "got lost in the system because he wasn't [diagnosed] but had problems learning to read and write."

But his problems were not "bad enough to get special assistance", she said.

It has been nearly four years since Ms Ban was killed in Brisbane.

Alex, formerly of Ipswich, and now 23, has pleaded not guilty to murder.

His father Geoffrey said he now wondered whether he was too "dismissive" of problems his son had.

"I look back and say, what are my failings as a parent?" Mr McEwan told the court.

The court heard Alex mentioned a presence in his bedroom, telling his father: "It's like there's something standing beside me. It feels like something there."

Geoffrey McEwan said he recalled thinking: "I don't know how to deal with that".

The father said he was "dismissive" because he wanted to think the best of people.

"If that's my failing, I could say I've failed."

Mr McEwan said he and Ruth "spent a lot of time managing" Alex in the mornings.

"He would lose things, his money, his wallet, his ticket to the train station."

"Alex was, I guess, struggling for a long time, in the sense of, his routine was never get up, go to work, go home and repeat."

Alex McEwan was 19 when Ms Ban was killed on Sunday, November 24, 2013 and her body dumped under a pine tree in Brisbane's Wickham Park.

Forensic pathologist Dr Alex Olumbe told the trial either manual strangulation or "blunt trauma such as stomping" would have caused injuries found to Ms Ban's neck.

Dr Olumbe said any one or combination of three factors could have caused Ms Ban's death.

She likely suffered inhalation of blood to her upper airways and lungs when unconscious.

Ms Bam also sustained facial injuries "which were very disruptive" and could have compromised breathing.

Thirdly, she suffered internal and external blood loss, causing shock.

The trial continues.