Jury may decide on mental impairment in Costa murder trial

Defence barrister Remy van de Wiel, QC, told an ACT Supreme Court jury that the trial simply decided whether the accused would be sent to jail or somewhere else.

"He's not going anywhere. He doesn't get to go home," Mr van de Wiel said on Monday during his closing submissions.

"This trial is not about him going home. But where he will go."

Chief Justice Helen Murrell gave jurors final directions and sent them out to begin their deliberations on Monday afternoon.

They were later sent home for the day and will reconvene on Tuesday morning.

Terrence Freebody, 89, was found dead on the dining room floor of Costa's Mugga Way home on July 22, 2012.

He had suffered fatal knife wounds.

The Crown alleges Costa pushed Mr Freebody off a chair, stomped on his face and neck, and then stabbed and cut him in a drunken attempt to dispose of his body.

Costa, 71, has pleaded not guilty in the ACT Supreme Court to murder.

The trial hinges on whether Costa was mentally impaired at the time of Mr Freebody's death.

During her directions, Chief Justice Murrell indicated, that if he were found not criminally responsible, she would order Costa remain in custody until a tribunal decided otherwise

Supreme Court juries are usually given the option of returning verdicts of either guilty or not guilty.

But the jury in the Costa trial has been given a third option – to find Costa not guilty by way of mental impairment.

Costa's defence team has argued their client suffers from dementia and, therefore, is not guilty of murder by way of mental impairment.

But the Crown – led by Shane Drumgold – argues that Costa faked his symptoms to escape prosecution for Mr Freebody's death.

During the 11-day trial, jurors heard the Freebodys lived across the road from Costa and had been invited to his home for a drink on the afternoon of July 22.

But Costa's foul language drove Mr Freebody's widow away about 5pm, and the accused called triple zero for assistance only minutes later.

Police arrived about 5.30pm to find Mr Freebody dead and Costa in a nearby toilet, covered in faeces and with blood on his hands.

A bloody knife was found on a nearby sink.

Jurors have also heard the triple-0 calls made by Costa, a police recording made after his arrest, and a number of expert opinions that the defendant suffered from dementia.

In his closing submissions on Friday, Mr Drumgold argued that the experts' diagnosis relied upon flawed testing and ignored recognised medical methodology.

Mr Drumgold said Costa had been living an active life, managing a large real estate portfolio and household, going on ski holidays, driving, and socialising before his arrest.

He also argued Costa's alcohol consumption at the time could explain his loss of memory, his emotional fluctuations, aggression, over-reaction, bad decisions, and disinhibition.

But Mr van de Wiel said the prosecution case relied on a "conspiracy theory" that four experts could all reach a false diagnosis.

He told jurors the evidence of dementia "is there if you know what you're looking for".

Mr van de Wiel pointed to evidence that Costa's finances were in disarray, large volumes of food in his home were out-of-date, his personal appearance had begun to decline, and he showed up to non-existent appointments.

"The gears are not moving too well you might think. This is not a man who is in control," the lawyer said.

"Yes, he's got property investments, yes he's got tenants, yes he's got money.

"But who is running it?"

He also dismissed the prosecution theory that his client had merely been drunk and angry.

"Yes he's affected by alcohol, but he's not so affected he would do this.

"It's his brain illness, affected by alcohol, that made him do this."