A five-day coronial inquest into the death of Cooper Scifleet last year heard the baby was most likely shaken to death in 2009.

After handing down her findings, NSW Coroner Mary Jerram called for the introduction of a new offence for cases where a child is deliberately seriously harmed and it is clear that one of a closed group of people has inflicted the injuries, but there is not enough evidence to prove who is responsible.

Under such an offence, which has already been introduced in Britain, all members of the group would be charged in relation to the child's death.

A spokeswoman for Attorney General Brad Hazzard told The Daily Advertiser yesterday the deliberate infliction of injuries on children was regarded as a very serious matter.

"Inquiries have been made to see what the practice regarding this offence is in the UK," the spokeswoman said.

"Further inquires are now being made in New Zealand and South Australia.

"Given the seriousness of the offence it is important to fully research all options."

The spokeswoman said a final decision was yet to be made.

Cooper's parents, Gary and Rebecca Scifleet, were initially unable to explain what had happened to their son, but later suggested a number of possible causes, including a slip in the basin while bathing, a car accident, and the involvement of the infant's three-year-old brother.

The coroner rejected those explanations and concluded that, on the balance of probabilities, Cooper had been "shaken with such force that he suffered injuries that subsequently led to his death''.

"The shearing nature of the brain injuries, the manner in which retinal detachments came about, and the number and nature of the fractures found in a four-week-old baby are ... all strongly indicative of traumatic origin,'' Ms Jerram said in her findings, which were handed down on October 30.

Cooper was four weeks old when taken to Cootamundra District Hospital and five weeks old when he died in Westmead Children's Hospital.

- with The Sydney Morning Herald