Maree Mavis Crabtree is accused of killing her 26-year-old son Jonathan with an overdose of painkillers on July 19, 2017 in the family's home north of the Gold Coast before making a $125,000 insurance claim.
The 59-year-old has also been accused of attempting to murder her son in January of the same year.
Crabtree pleaded not guilty to murder, attempted murder and fraud charges when her trial began at Brisbane Supreme Court last week.
The jury on Friday began watching nearly five hours of video evidence from the accused's daughter Tara Crabtree that was pre-recorded on Tuesday and Wednesday.
Tara said she was one year younger than Jonathan at the time he died and living with him and Crabtree.
The jury heard Tara claimed Crabtree crushed up prescription painkiller and anti-anxiety tablets while Jonathan was passed out in bed.
"She cut up fruit and put it in the blender to blend it ... watermelon, pretty sure mango, pineapple are the main ones I remember," said Tara, who has immunity from prosecution.Â
Tara said Crabtree crushed up tablets with a hammer on a chopping board on the kitchen bench and added the powder to the fruit smoothie along with six bottles of liquid oxycodone opiate painkiller.
"She asked me to keep lookout for my brother. He came out and she gave it to him," she said.
Crabtree sat in the dock looking at the TV screen located near her feet while her daughter's evidence was played on Friday.
The jury previously heard Jonathan's behaviour had been severely affected by injuries he sustained in a car crash.
Crown prosecutor Caroline Marco asked Tara why Crabtree had put drugs in Jonathan's smoothie.
"He was violent, a horrible person to live with ... we would have more peace and live a better life without him, that's what she said," Tara said.
The jury previously heard Jonathan co-owned the family home and could not be evicted.
Tara said she had heard Jonathan struggling and making noises after he returned to his room with the smoothie but Crabtree told her not to interfere.
She testified that Crabtree feared she would be arrested and "lose everything" and Tara would be forced to live in a group home if Jonathan survived.
The jury also heard Tara claim Crabtree was concerned about the financial impact of Jonathan being sued by a person he allegedly threatened during a robbery of a pharmacy.
Tara said she was in "shock" after Jonathan died and Crabtree told her not to say anything if the police arrived.
"He committed suicide, that's what she told me to say," Tara said.
The jury is due to see video of Crabtree's defence barrister Angus Edwards cross-examine Tara about her claims.
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