A "spectrum of possibilities" would remain, Katherine White said while giving expert evidence at the High Court at Palmerston North.
Doctor White conducted a post- mortem examination of Mr Waipouri on December 24 last year, a day after his grisly death at his home on Rangitikei Street.
Mr Waipouri died from significant head and neck injuries.
There were no defensive injuries, or injuries caused through defending himself, found on Mr Waipouri's body, Dr White said.
Under cross examination by Gilling's lawyer Mike Antunovic, Dr White said she couldn't definitively state whether or not a single blow caused the death of Mr Waipouri.
Other injuries, including those sustained to his ear, his penis and his nipples, were thought to have been inflicted while he was dying, Dr White said.
The post mortem revealed the tip of the penis had been cut off along with further mutilation, Dr White said.
It was not know what instrument was used to sever the penis.
The examination also found a fragment of bone protruding through the skin, above Mr Waipouri's left eyebrow.
Impressed into it was a small linear pattern, Dr White said. This week, the court has heard such patterns can be caused by fabric imprints.
Dr White told the court a blood sample from Mr Waipouri revealed 301mg of alcohol per litre of blood. The legal limit is 80mg.
No other notable substance was found.
Dr John Goulden presented findings of CAT-scan of Mr Waipouri's body to the jury yesterday.
A head scan, and a subsequent 3D reconstruction of the skull and face, revealed shattered bone fragments in the mid-face section, extensive swelling around the brain, and showed two lower incisor teeth had been displaced.
Mr Waipouri's facial fractures were consistent with assault or motor vehicle trauma.
However, Dr Goulden said he'd not "seen such severe frontal fractures on any living person".