© 9NewsAlaine Sturniolo, 39, killed her grandmother by swapping her pills with morphine tablets prescribed for her uncle before he died of cancer.
A Perth woman has wept uncontrollably as she was found guilty of murdering her 91-year-old grandmother by tampering with her medication nearly a decade ago.
Dawn Baldwin was found collapsed in her Wembley Downs home in 2012 and died in hospital a week later.
A jury found her granddaughter Alaine Sturniolo, 39, killed the elderly woman by swapping her pills with morphine tablets prescribed for her uncle before he died of cancer.
Sturniolo might have got away with the crime had she not bragged about it to relatives including her sister and former brother-in-law, who dobbed her in to police in 2017.
Seven months before the murder, the mother-of-two posted on Facebook, "What is the one thing you wish you could change about your life - Debt, and my grandmother's life status mwahahahahahaha".
A month later, she wrote "Something I hate - Grandma".
© 9NewsThe pills were swapped with morphine.
Her lawyers argued that was a joke and it was possible another person deliberately or accidentally substituted the pills, including Dawn Baldwin herself.
They also argued Sturniolo's sister and former brother-in-law had an "axe to grind".
But the 39-year-old was found guilty on Tuesday and will be sentenced in July.