Days before Tanilla Warrick-Deaves died, her mother's boyfriend allegedly boasted "watch me make her scream" as he forced the two-year-old to run laps of her lounge room.
Warren Ross, who is on trial for the child's murder, then made the toddler "squeal" by lashing her with his belt, acquaintance David Wilson told the Supreme Court in Sydney on Thursday.
"It was pulling on my heartstrings to see a little two-year-old like that," Mr Wilson told the court.
"I thought myself the punishment was way too harsh."
Ross is on trial for the murder of Tanilla, the daughter of his girlfriend Donna Deaves, at her Watanobbi home on the NSW Central Coast on August 25, 2011.
He has pleaded not guilty.
The Crown alleges Ross abused the child in the weeks leading up to her death as he attempted to toilet train her, forcing her to run laps, whipping her with various implements and hitting her.
Mr Wilson told the court he called at the home in August 2011, several days before the toddler died.
He saw the "distressed" toddler attempting to run laps of the lounge room while Ross ordered her to "pick up the pace".
"I hit her with a cord. I hit her with a strap," Ross allegedly said, adding that "she deserves it".
Mr Wilson said Ross told him the child was being punished because she had picked up his heavy tool box and dropped it on her hand.
Ross then unwrapped the bandage on the girl's hand and showed it to Mr Wilson, the court heard.
"Her hand was as big as mine," Mr Wilson said.
"She couldn't move her fingertips."
Deaves was sitting in the lounge room at the time but did nothing, Mr Wilson added.
The trial also heard from next-door neighbours Paul and Wendy Coker, who took note of what they say occurred in the house in August 2011.
Ms Coker said she often heard Ross "chastising" Tanilla.
"The chastisement that I heard was slapping and yelling," Ms Coker said.
"It really was to do with toilet training. That's when it got out of control."
A couple of weeks before Tanilla's death, Ms Coker said she heard Ross yell at Tanilla, "You f***ing little black bastard, you shit yourself."
She said she was scared and asked her husband to go outside and see what was happening.
"It sounded like someone being whipped by a belt," Mr Coker told the court.
"It went on for about 30 to 35 minutes".
He said the whipping only ended after he heard Deaves yell "enough".
The Cokers informed the Department of Community Services (DOCS), who visited the house the following week.
Tanilla died in Wyong Hospital just days later on August 27 having spent two days lying injured in a pram, the court has heard.
The Crown alleges Ross beat her, made her run laps and held her over the toilet bowl by one leg before causing her to hit her head on a door.
The day before Tanilla died, Ms Coker said she saw Deaves and Ross standing in their garden looking "very subdued".
She said she thought it was strange because "they were (usually) very vocal".The trial continues before Justice Stephen Rothman.