An abusive Australian husband wrote down the names of his four children and demanded his wife pick which one he would kill, a Brisbane jury has been told.

Lawyers for accused murderer Susan Falls told Brisbane Supreme Court yesterday the "normal mum" from Caloundra had been subjected to more than 20 years of violence from her husband, Rodney Falls.

Mrs Falls, 42, has pleaded not guilty to murdering her husband by lacing his dinner with crushed sleeping pills then firing two bullets into his head as he dozed in his favourite recliner at their home on May 25, 2006.

The shooting took place in front of two of the couple's teenage daughters, while another daughter was also in the Nicholas Street home and the Falls' three-year-old son slept nearby.

In opening Mrs Falls' defence case yesterday, barrister Jeff Hunter told jurors his client did not deny she killed her husband but claimed she did so because, she said, she "just wanted to end the violence and the fear me and my girls were feeling".

"What has happened to her to make her ... think the only way out is to drug her husband and shoot him in the head?" he asked.

"She firmly believed sooner or later she was going to be killed [by him]."

Mr Hunter said days before Mr Falls' death, his client's parents had been planning to visit, which had angered Mr Falls and apparently prompted him to threaten to kill one of the couple's children.

"He actually wrote their names down on a piece of paper and forced her to pick one," he said.

Mr Hunter said the jury would hear evidence that Mrs Falls had police serve a domestic violence order against her husband and the police officer involved in that matter warned Mrs Falls that her husband "would eventually kill her".

The officer, Mr Hunter said, would testify that after 16 years of police work she was deeply concerned for Mrs Falls.

Mr Hunter said the officer had written a statement saying: "I told Susan if she stayed with Rodney he would eventually kill her".

Mr Hunter said Mrs Falls believed no one could protect her from her husband, admitting: "so I just got him. He would kill me, it was just a matter of when. I thought that my only escape was to do what I did".

Earlier yesterday, the trial heard that after shooting her husband Mrs Falls "parked" his dead body in front of an air conditioner for three days where it "got smelly", before she enlisted the help of three men, who face trial alongside her.

Christopher Anthony Cummings-Creed, 25, Anthony James Hoare, 42, and Bradley James Coupe, 30, have each pleaded not guilty to being an accessory after the fact to Mr Falls' murder.

The court was told Mr Coupe and Mr Cummings-Creed disposed of the recliner chair, the gun and the clothes Mrs Falls had been wearing at the time of the killing.

Mr Hoare is accused of helping to dump Mr Falls' body - wrapped in bedding and tarpaulin - in the Mapleton State Forest where it was found in late June 2006.

Prosecutors told the jury that after the "cold methodical killing" Mrs Falls had created "an intricate and elaborate lie" by telling police for several weeks that her husband was missing, even going to the media in a bid to find him.

It was only in late June - four weeks after his death - she admitted she had killed him and detectives were led to his decomposed corpse.

The trial, before Justice Peter Applegarth, continues today.