Brittney Dwyer was just 19-years-old when she murdered Robert Whitwell in his home of Craigmore, Adelaide, last August.
Tonya Dwyer, hasn't spoken to her daughter in more than a year and still struggles to comprehend her heinous crime.
'I think she deserves 20 years in jail. She did the crime. She admitted to it. She pleaded guilty,' Tonya told Melissa Doyle in an exclusive Sunday Night interview.
'I have lost two people, I have lost my dad and I have lost my daughter, and I don’t know if I will ever understand the whole story.'
According to reports, Dwyer's motivation for murder was money, after hearing of a small fortune that her 81-year-old grandfather had in his possession.
Like many, Robert didn't trust the bank with his life savings, so it was hidden in his garden shed.
It was later revealed that Dwyer convinced her 22-year-old friend Bernadette Burns to drive 2000 kilometres from her home in Brisbane to Adelaide to do 'whatever was necessary' to steal Robert's savings.
While Burns waited in the car, Dwyer knocked on the door of her grandfathers home and greeted him like it was any other normal visit.
Robert Whitwell spent the last moments of his life showing his granddaughter photo albums of her childhood. Then, when he walked her to the door, she stabbed him repeatedly in the neck and chest.
She never found Robert’s $100,000, but stole $1000 from his wallet and two digital cameras before driving back to Brisbane.
On Sunday Night, Tonya was overwhelmed by questions.
'What are the signs I missed? What did I miss? What didn't I see? What didn't I pick up on?' she asked.
'It was a person that I trusted, that I brought into the world, that I raised to be a good person.'
She continued, 'It’s like a nightmare that I never wake up from. Every day I think, ‘when is this nightmare going to finish?’ And it doesn’t. It’s my life.'
The aftershocks of the murder have been devastating. Tonya separated from her husband, and Robert’s beloved wife, Joyce, died in a nursing home shortly after his murder.
Dwyer is currently awaiting sentencing in Adelaide Women’s Prison, less than half-an-hour from Robert’s home.
Both Dwyer and Burns will be sentenced on November 7.
This article originally appeared on New Idea.