Spencer Jordan and Marie Magoon are charged with first-degree murder in the death of Meika Jordan in 2011.
The girl's biological father and his spouse are accused of burning, punching and throwing the girl down the stairs.
Jordan’s lawyer Mitch Stephensen said Tuesday afternoon that it was impossible to determine who struck the fatal blow and also questioned Magoon’s credibility.
Crown prosecutor Susan Pepper said in her final arguments that both accused committed crimes which were sufficient to cause fatal injuries.
Magoon’s lawyer Allan Fay said Magoon had admitted to burning Meika with a lighter and other assaults, but none caused fatal injuries.
Fay also said Magoon was a “stranger to the truth.”
Both Magoon and Jordan told undercover officers pretending to be crime bosses that they burned, punched and pushed the little girl.
The judge ruled the recorded confession could be admitted into evidence.
Medical officials have testified Meika died of blunt force trauma to her head. Her pancreas and liver were torn and she was badly burned.
Judge Rosemary Nation will hand down her decision June 3.