Zahra's stepmother charged with murder

Zahra Baker was murdered and then dismembered, but an autopsy on the 10-year-old Australian girl's remains failed to determine exactly how she was killed.

"Based on the history and autopsy findings, it is our opinion that the cause of death in this case is undetermined homicidal violence," the autopsy report by the North Carolina Medical Examiner states.

The report was released hours after District Attorney Jay Gaither announced a grand jury in North Carolina had charged Zahra's US stepmother, Elisa Baker, with second-degree murder.

Baker, 42, faces eight to 30 years in jail if convicted of Zahra's murder.

Zahra's biological father Adam Baker has not been charged and Mr Gaither said there was "no credible evidence to suggest that anyone other than Elisa Baker was involved in the murder of Zahra Baker".

Zahra's skull, right arm, right leg, left forearm and hand remain missing.

The autopsy report does offer hints about the grisly dismemberment and disposal of parts of Zahra's body in bushland around her adopted hometown of Hickory, North Carolina.

Bones found by authorities had "distinct cut marks", the autopsy report states.

"Several of the bones exhibit cutting tool marks that are consistent with dismemberment," according to the autopsy report.

"The marks grossly appear to result from the use of at least two different cutting instruments."

The cut marks on the bones "indicate that the decedent was dismembered and are presumed to have occurred postmortem".

The report also describes how "multiple allegations of abuse" on Zahra "were reported to Department of Social Services during 2010".

Zahra was last seen alive on September 24, 2010, but was only reported missing by her father on October 9.

Elisa Baker can't be sentenced to death if convicted of murdering her stepdaughter.

Mr Gaither's office declined to discuss with AAP the decision to charge Elisa Baker with second-degree murder, rather than a more serious first-degree charge that could carry a death sentence.

Police who led the investigation supported the charge.

"We concur with the decision made today by the Catawba County grand jury," Hickory Police Department chief Tom Adkins told reporters.

The DA did say at a press conference investigators did not have "credible evidence" anyone other than Elisa Baker was responsible for the death of the young girl.

Zahra's biological father Adam Baker was forced into hiding after angry locals hounded him in his adopted hometown of Hickory, North Carolina, after Zahra went missing four months ago.

Mr Gaither's comment points to Mr Baker, a former Queensland sugar mill worker, not being charged with the death of Zahra.

"At this time the state has no credible evidence to suggest that anyone other than Elisa Baker was involved in the murder of Zahra Baker," Mr Gaither told reporters.

Zahra went missing in late September last year and weeks later parts of her dismembered body and prosthetic leg were found scattered in bushland outside Hickory.

The second-degree murder charge includes aggravated circumstances such as Zahra was "handicapped" and Elisa Baker "took advantage of a position of trust" and "had a history and pattern of physical, verbal and psychological abuse of the victim".

"Elisa Baker secreted the victim Zahra Baker from family and others prior to and after the offence delaying the detection of the offence," Mr Gaither, listing the other aggravating factors, said.

"Elisa Baker desecrated the body of Zahra Baker to hinder detection, investigation and prosecution of the offence."

Zahra needed a prosthetic leg and two hearing aids after battling bone cancer.

Adam Baker is free on bond, facing numerous charges not related to his daughter.

He may become a key prosecution witness in the case.

Zahra and her father moved to the US two years ago to be with Elisa Baker. Elisa and Adam Baker met on the internet and married in Queensland, however US authorities have charged her with bigamy because they believe she was still married to an American man at the time.

- AAP