TWEED police have been unable to find how Greg Hutchings and daughter Eeva Dorendahl-Hutchings died, but they still expect to release their bodies to family in the next couple of days.

A post mortem by a coroner on the father and his daughter has been completed, but due to the dire condition of the remains no concrete information on how they died has been found.

"At this stage no cause of death has been established due to the bodies being there for so long," Tweed Byron LAC Detective Superintendent Stuart Wilkins said.

"We're taking other steps to establish cause of death and we're going through the forensic process, keeping an open mind.

"Hopefully they (bodies) will be released within the next couple of days."

The coroner responsible for finding out how the pair died will release a report to NSW Police at a later date.

Mr Hutchings and Eeva's bodies were found in beachside scrub at Pottsville on January 28, following an intensive 17-day search.

A murder investigation was launched by Tweed police, with Det Supt Stuart Wilkins previously saying a murder-suicide was not being ruled out.

Before the discovery of the bodies by an SES search volunteer, the pair had not been seen since they were last sighted at Pottsville Rd, Pottsville on Saturday, January 11.