A six month-old baby was referred to as "zombie boy'' after being held upside down, violently shaken and dropped on a bed, the Crown says.
James Hemana has denied murdering baby Cezar Taylor but pleaded guilty to failing to provide the necessaries of life.
Cezar was taken to Middlemore hospital with severe brain injuries and died five days later on July 28, 2010.
Crown prosecutor Josh Shaw opened the Crown case this morning and told the court that Hemana's cousin took two photographs of baby Cezar on her mobile phone, days before he was admitted to hospital.
"He was constantly vomiting, barely awake and his eyes would roll. He was referred to as 'zombie boy','' Mr Shaw said.
He said Hemana was living with baby Cezar's mother in Mangere and was jealous of the six-month old. He would also get angry when the baby would cry.
Mr Shaw said that on one occasion, Cezar was crying and woke Hemana, who yelled and swore at the baby.
Hemana is alleged to have grabbed the baby by the front of his onesie pajamas.
"He violently punches him back and forth repeatedly before dropping him on to the bed.''
Mr Shaw said Hemana also picked Cezar up by one leg and again violently shook him before dropping him on the bed.
He said Cezar's mother, Victoria Taylor, tried to intervene. Hemana is alleged to have told her: "I don't give a f***, b****. I'll waste all of yous''.
Mr Shaw said Ms Taylor described her son as a "very different baby'' after the two incidents.
"Most of the time he was effectively lifeless and unresponsive.''
He read from a statement from Ms Taylor: "Before he was alert. He would talk away, watch TV. Now he just sits there and rolls his eyes. He looked like a dog and just sat there.''
It was about five days later that Ms Taylor took her son to hospital. Mr Shaw said she was prevented from going earlier by Hemana.
He said Hemana did not go to the hospital with Ms Taylor, told her not to mention him and to say bruises on the baby's head were caused by bumps and falls.
"In short, in anger and frustration, he gambled with Cezar's life and ultimately took his life.''
The jury of six men and six women is set to hear from 54 witnesses over the next two weeks.
The trial continues.