A little girl said to have died from a violent blow to the stomach delivered by her step dad would often turn up to her grandmother's with itchy skin and smelling "so bad".

Michael Joseph Martin, 25, has pleaded not guilty to murdering 2-year-old Leilani Mary-Jane Lotonu'u at their Manurewa home in June 2012.

He is accused of hitting the child so hard an internal organ ruptured, resulting in a fatal infection.

Martin's lawyer Lorraine Smith told a jury in the High Court at Auckland today that Martin denied any wrongdoing and the child's mother Amy Lorigan was responsible for her daughter's death. Ms Lorigan denies this.


Ms Lorigan's mother Marie Chapman described how Leilani would often stay with her. Although she liked playing, she couldn't talk and her body was covered in sores.

Mrs Chapman agreed with the defence that Ms Lorigan didn't look after Leilani and another daughter she had with Martin "the way a mother should".

Leilani also "stunk so bad" because her clothes were never washed. Martin and Ms Lorigan, who had been together since early 2011, did not own a washing machine and their home reeked of urine, Mrs Chapman said.

Leilani was pronounced dead shortly before 6am on June 10, 2012, when paramedics were unable to save her.

The day before, Martin and Ms Lorigan were looking after the little girl but she was alone with Martin for about an hour when Ms Lorigan went grocery shopping.

It was then, the Crown says, that Martin administered a "violent assault" akin to a kick from a horse against his stepdaughter, who he resented.

Expert evidence would suggest the girl was in great pain but would have survived if she received prompt treatment, Crown prosecutor Christine Gordon, QC, said in her opening statement.

When Ms Lorigan arrived home, Martin told her their relationship with over. He did not tell her what he would later tell police that Leilani had fallen off a chair.

This was his attempt to explain Leilani's injuries, Ms Gordon said.

She said Martin "misled" police about his feelings for Leilani and the state of his relationship with Ms Lorigan.

"Amy Lorigan loved her daughter Leilani. The accused, however, struggled to accept a child that wasn't his and was going to leave."

Mrs Smith said Martin did not injure Leilani and did not see anything happen to the little girl.

"He has no history of child violence. No one has seen him smack Leilani or even smack a child. The bottom line is there's no evidence whatsoever that Michael Martin was responsible for Leilani's injuries.

Mrs Smith said Ms Lorigan did not seek medical help for Leilani when she vomited throughout the afternoon of June 9, 2012, and was heard by a neighbour shouting at her.

Martin has also pleaded not guilty to a charge of child neglect for failing to provide Leilani with medical assistance.

The trial, before Justice Graham Lang, is expected to last about three weeks. The Crown is due to call 35 witnesses.