ALEX Reuben McEwan's sister knew something was wrong, a jury has been told.

It was Sunday, November 24, 2013 -  the day Eunji Ban died.

Emma McEwan was 16. Her brother, then 19, had in recent years become more withdrawn.

The siblings had been close as they grew up, and used to have deep conversations about life.

"We didn't do that anymore. His temper was a lot shorter," Ms McEwan told Brisbane Supreme Court, where her brother is on trial for murder.

Her brother had always "looked out" for her, she said on Thursday.

But now, she was the one concerned for him.

"It was hard to get through to him. He had more trouble articulating things than he used to."

Her brother's room in the family's Spring Hill apartment was next to her own, and she would sometimes hear disturbing noises.

"Sometimes I heard a lot of banging on the wall, sometimes talking or yelling in his sleep."

But her brother never spoke of a desire to kill or even harm people, Ms McEwan said.

Mr McEwan, formerly of Ipswich and now 23, has pleaded not guilty to murdering Ms Ban.

Ms McEwan said her brother was acting so strangely that Sunday, she had to ask him "What the f**k is wrong with you?"

The trial heard Mr McEwan told police the next day, November 25, of a demon troubling him.

He told police it seemed as if he was possessed, when Ms Ban was attacked and killed, her body dumped in Wickham Park.

After Mr McEwan was arrested, his sister sent a Facebook message to one of her friends

The court heard Ms McEwan told the friend: "Yes, it was my brother."

"I spoke to him one last time before and he couldn't even look at his own family because he was so ashamed."

The trial heard she also told her friend Mr McEwan was "not sober" when Ms Ban was killed, and spoke of being possessed.

"I believe him - and he has been showing signs of it since he was 16."

Prosecutor David Meredith asked Ms McEwan if she believed what she said then about her brother's mental state.

"I was trying to make people know that it wasn't really him,' Ms McEwan said, crying.

"I just didn't want people to think he's a horrible person, because he's not."

As the sister he had "always looked out" for left court, Mr McEwan could only look down, his face buried is his hands

The trial continues.

-NewsRegional

EARLIER: A MURDER trial jury has been told they can expect to hear evidence Alex Reuben McEwan has schizophrenia.

Mr McEwan, 23, is accused of murdering Eunji Ban in central Brisbane in November 2013.

Justice Jean Dalton told jurors on Thursday morning that issues related to Mr McEwan's health were the cause of a delay on Wednesday, when jurors were sent home early.

Ms Ban, a student from Korea aged 22, was found dead in Wickham Park.

In an audio recording played to the jury earlier, Mr McEwan told police he "bashed the s*** out of her face" and spoke of a demon tormenting him.

Mr McEwan, a 23 year-old formerly of Ipswich, has pleaded not guilty to murder.

The trial continues.