A three-year-old boy watched in wide-eyed horror as his mother attacked his screaming grandmother, the South Gauteng High Court in Johannesburg heard yesterday.

"I looked over the wall and I saw two ladies and a small boy," said Madeleine Pieterse, a witness in the trial of Lerato Monamodi, 33, who is charged with the murder of her mother, Refiloe Rebecca Monamodi, in March last year.

"One lady was lying on the ground," Pieterse said.

"She was being dragged and pulled from the house to the door. The one pulling was wearing a white [night] gown. The lady who was lying on the ground was the one screaming.

"She was just lying flat. There was no defence. All she could do was scream."

Pieterse said she also eventually screamed, to get some attention, and the child responded.

"The boy turned and looked at me. He was obviously terrified. He said: 'Mommy is pulling my grandmom'.

"It's like he was asking me to help."

Pieterse told the court Monamodi would not stop assaulting her mother despite threats that the Pieterses would call the police.

Pieterse said Monamodi was her immediate neighbour and that their houses were separated by a security wall.

She told the court she woke up at 6am and, as she went out to feed her dogs, she heard loud, anxious screams.

"It was very odd for something to happen around that time on a Sunday morning," Pieterse said.

She said Monamodi looked at her and told her "everything was under control".

"I said to her I am going to call the police because she just continued. There was a stage where she hit her mom with her foot on the head."

Pieterse said the incident traumatised her and her children and she took them inside and there was silence.

"I told my husband that the lady is dead. I went out and looked over the wall again and I heard the water splash.

"I saw the lady in the white gown bending forward next to the pool. The boy was standing there staring at something. He was motionless, like frozen. I could not see the other lady."

Pieterse's husband, Warner, confirmed her version.

He said at some point Monamodi banged her mother's head and fiddled with a garment around her neck.

The Pieterses had been living in the area for seven months when the incident occurred, he said.

The couple confirmed that they saw Monamodi only when she had parties on her own where she sang loudly and danced alone at night.

Monamodi has pleaded not guilty to murder.

The trial continues.