HOMICIDE investigators say a child who died in Mandurama did not have injuries consistent with a fall.
A 35-year-old man, believed to be the baby's stepfather, took the 11-month-old girl to Blayney Hospital with head injuries on Wednesday morning.
Doctors carried out CPR on the infant but could not save her.
Police were told the baby girl had fallen off a trampoline at the family home in the village of Mandurama.
However, NSW homicide squad commander Detective Superintendent Mick Willing told reporters the child's injuries were not consistent with a fall.
"The deceased child will be subject to a post-mortem examination later that will hopefully tell us what happened," he told reporters.
"... we have some concerns about some injuries that the child is displaying."
Local police want to hear about the family's movements leading up to the infant's death.
"We really want to hear from anyone who may have information about the family or the movements of them around that incident," Bathurst police Detective Inspector Luke Rankin said.