A jury in the Palmerston North High Court has today found a man not guilty of murdering his then partner's three-year-old daughter but guilty of her manslaughter.

Sean James Donnelly, 23, was accused of murdering Kash McKinnon, who was found unconscious with head injuries at a Hulme St, Palmerston North, house on August 19, 2009.

She died of head injuries in Palmerston North Hospital the next day.

A jury of eight women and four men deliberated for just two hours before reaching its verdict, the Manawatu Standard reported.

Donnelly, who was the former partner of Kash's mother, told the court the injuries were caused by accident.

He had hit Kash after she had put a toilet roll into the toilet bowl, he said.

Kash had told him she did not have to listen to him when he decided to spin her around by the ankles, because he did not want to hit her again, Donnelly said.

However, he had become dizzy and let her go.

He saw her stumble around for a few minutes before falling unconscious.

"I thought she had just gone to sleep - she was dizzy and just gone to sleep," Donnelly said.

Crown prosecutor Chris Shannon argued Donnelly's story did not add up.

Donnelly was remanded for sentencing on March 25.