That is a tough case. I know that many countries (for example, US is one) have laws that teachers and others who have contact with children are required to report even a suspect of child abuse. If they see a child with unexplained bruises, they have to report it to an authority. Otherwise, they can be "held liable".
Is even 16 months in this case too long? I dont know. Very sad all around. Everybody lost in this instance.