Moko died in Taupo in August last year while in the care of the couple.
Moko's mother, Nicole Dally-Paki, was in Auckland with another child who was sick in Starship Hospital, and asked Shailer to take care of Moko and his older sister while she was away.
A post-mortem examination revealed Moko died as a result of "multiple blunt-force traumas".
He had lacerations and haemorrhaging deep within his abdomen, historic bruising and damage to his bowel. Combined, that resulted in his bowel rupturing. Faecal matter leaked into Moko's abdomen, causing septic shock. His brain was swollen, he had blood clots under his scalp representing numerous injuries inflicted at different times.
There was evidence the toddler had been smothered. Moko had human bite marks, contusions, abrasions, deep bruising, lacerations, patterned injuries on his face, chin, neck, ears, lower lip, gums, eyes, ribs, testes, skin, chest, tummy, shoulder and arms.