Police in Auckland say a post-mortem shows a two-year-old boy suffered blunt force trauma to his stomach, and had severe damage to his internal organs.
James Lawrence, known as JJ, died before ambulance services arrived at his home in the suburb of Orakei. He was buried on Thursday.
Detective Inspector Scott Beard says some accounts of what happened to the child are not consistent with the results from the post-mortem.
He says the police understand four adults and three children were present at the time of his death.