"This is what God wants," Lotter said she told her 53-year-old mother, Maria Magdaline "Riekie" Lotter.
An emotional Lotter, now 29, said that if she had not believed it was what God had wanted, she would not have done it.
She said she was told by her then boyfriend - Mathew Naidoo, now 25, the alleged mastermind behind the murder of her mother and 53-year-old father, Johannes Petrus Lotter - that he was the third son of God, and that God wanted her parents dead as they had sinned.
"If Mathew had not lied about God, it would not have happened," she said, fighting back tears.
Lotter and her brother Hardus, 23, as well as their co-accused Naidoo, face charges of murdering the senior Lotters at their Westville home outside Durban in July 2008.
Lotter said that she and her brother would not have received anything from the inheritance from their parents.
"It was all going to go to Mathew," she said.
And she claimed that Naidoo's mother, Rita, was also implicated in the double murders for financial benefit.
Lotter said that Naidoo's mother had said in a statement to police that she (Lotter) had complained to her that she had wanted to kill her parents.
If true, Naidoo's mother could have prevented the murders by telling the police and warning her parents that their daughter was insane and wanted to kill them.
She could have prevented the murders, but did not as she was going to benefit from it financially.
Lotter said Naidoo had told them the day before the murders that their parents had been condemned to death for their sins.
This message came from three "beings", including the angel of justice, James.
Naidoo had told her and her brother to come up with a plan to murder their parents, and when they could not he slapped them in the face.
Then Naidoo told them that their parents had to be shot with a Taser [an electroshock weapon] and have air injected into their veins to induce heart attacks.
Asked how she felt about this, she said she could not oppose God, but was relieved that her parents would not feel pain.
After separating their parents and luring their mother to the kitchen, her brother came in with a Taser, she recalled.
Her brother did not want to Taser their mother and switched on the torch light instead of the Taser, she said.
As the Taser did not knock their mother out, they assaulted her.
She tried injecting air into a vein, but could not find one.
'We did not know how to kill someone," she said, so she drove to the nearby Pavilion shopping centre and collected Naidoo.
Her mother was still alive and bruised from the assault and her brother was holding her mother down, she said.
When she brought Naidoo back to the house, Naidoo told her that she had to stab her mother.
When she told him that she had done it, he told her several times to go back and make sure her mother was dead.
"I had to go back and stab my mother. I don't know how many times."
When Naidoo was finally satisfied her mother was dead, he said: "Good riddance to that bitch."
He had stood over her body and said she was such a hateful woman, she deserved to die.