TWO teenagers who brutally murdered a helpless 87-year-old grandma were "high on evil and the thrill of murder" when they sliced her throat with a blunt hunting knife, an Adelaide court has heard.
Retiree Anne Redman had gone into her yard with a torch to investigate why her power had been shut off when she was attacked by a 16-year-old boy on Australia Day last year.
The burglar, who can only be referred to as "B" and was the son of a serving South Australian police officer, punched her in the face and sat on her to keep her from getting away.
When his 17-year-old friend, known as "J" grabbed a blunt hunting knife from their car and returned to the yard, he allegedly said to "B" "I thought you would have knocked her out by now" to which he replied "I'm not going to knock her out, I'm going to kill her", news.com.au reported.
While the boy's lawyers gave varying accounts of the events that followed, Prosecutor Adam Kimber said there was evidence both were equally responsible for the murder.
According to Adelaide Now, Ms Redman's daughter Suzanne questioned why the boys had not fled when they were caught by a "doomed" and "outnumbered" elderly woman.
"They had not injected, swallowed or snorted anything to impair their judgement - they were high on the evil and thrill of murder"," she said.
Both teenagers will be sentenced to life imprisonment.
A judge will reveal how much of that time will be served in custody at a final hearing next week.