Del Graff also says in a report that there should have been greater assessment of risk factors in the child's case, so social workers could have apprehended her sooner.
The girl, almost 10 months old, was taken to hospital in 2012 with an unknown injury to her genitals.
A doctor had flagged potential child abuse, but she was sent home with her mother since her father — who had a history of domestic abuse — was not living in the house.
The child was admitted to hospital twice more in the days that followed with a head injury and broken bones.
Police later charged an occasional male caregiver, who had previously faced criminal charges, but social workers didn't know about him.