A woman who says she kept lookout before her brother was lethally drugged with a smoothie could have a "sinister" motive to accuse their mother of murder, a jury has heard.
Maree Mavis Crabtree is alleged to have killed 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.
