The grieving father of a murdered toddler has described his son's bashing as disgusting and inhumane.
BJ Williams was only two years old when he was beaten to death by Brock Michael Powell in January 2012, in an Adelaide granny flat he shared with his then-partner, the boy's mother, Latara Lee Hunt.
Justice Timothy Anderson last month found Powell, 25, inflicted BJ's extensive injuries after launching a vicious attack when he was slightly affected by alcohol and drugs.
Brendan Williams told the South Australian Supreme Court on Thursday of missing his son's laughter, smile and big blue eyes.
When he finally got to see him in hospital, it looked like "someone had smashed his head into the floor" he said.
After the toddler's life support was turned off, Mr Williams said he held his dying son in his arms, which had been the worst feeling ever.
If Powell had wanted a fight, he asked why he had not fought with an adult instead of bashing BJ in a disgusting and inhumane act.
Ms Hunt said she had lost an amazing little boy who had been perfect in every way.
"I will never forgive you Brock for the pain and suffering you have caused forever in my life," she said.
BJ's maternal grandmother, Karen Hunt, said she had only spoken about a dozen words to her daughter since the death of her beloved chubby grandson.
She also asked Powell to tell the truth about what happened, instead of the "garbage" he put forward about BJ falling from his bed and becoming wedged against a wardrobe.
The toddler's paternal grandmother said BJ always lifted her spirits by doing wacky things and she would miss the kisses he gave when he presented her with lavender from the garden.
Her strong son was now "crippled by grief" at being unable to protect his son, she said.
"How could a grown man beat a two-year-old?" she asked.
Powell will be sentenced on March 7.
