Rare grass pollen found in Mellory Manning's nose and on her clothes was an exact genetic match to plants from a Mongrel Mob pad, a murder trial has heard.
Scientists who examined the pollen said it was so rare it was "almost impossible" it came from any other site in the world.
That was because the ripgut brome grass growing at the pad, at 25 Galbraith Ave in Avonside, experienced a "genetic mutation" in the summer of 2008, which happened nowhere else.
Forensic palynologist Dallas Mildenhall today gave evidence on day five of the High Court trial in Christchurch of Mauha Huatahi Fawcett, 26. He denies murdering Manning on or about December 18, 2008.
The evidence baffled Fawcett, who, when asked if he had any cross-examination questions, said: "I'm confused about this one. I might just pass."
The Crown says Manning was picked up from the corner of Manchester and Peterborough streets, taken to the Mongrel Mob pad and fatally attacked before her body was dumped in the Avon River.
Police took grass samples from the Galbraith Ave address shortly after Manning's murder, including from a concrete pad.
Mildenhall examined the samples in early 2011.
"There was a genetic mutation at this site, that is why this is so unusual," Mildenhall said.
"For it to happen elsewhere would be remarkable. It is almost impossible."
He compared the pollen with that found in "abundant" amounts on the back of Manning's cardigan, which was on her body in the river. It matched.
The pollen had also embedded into the fabric of the cardigan. This showed it came in "direct and forcible contact" with the grass while she was lying on it. It could not have got so deep in the fabric from simply brushing past, he said.
Mildenhall determined the concrete pad, as well as a spot about 20 to 30 metres away, could not be ruled as "possible sites for the attack on Miss Manning".
Mildenhall also examined pollen found in Manning's nasal cavities, in a bid to determine where she died. This pollen also matched that from 25 Galbraith Ave.
It did not match pollen samples from other locations including the Avon River, Avonside Drive and Dallington Tce.
Therefore, Mildenhall could "not rule out" the possibility that 25 Galbraith Ave was the site where Manning drew her last breath.
Police identified 131 potential murder sites in the weeks after Manning's death. This was "shortlisted" to 32 sections, of which 19 were searched and investigated.
Police believed her body entered the Avon River about 11pm on December 18, 2008, leaving a short time frame in which the fatal attack took place.
The trial continues on Monday and the Crown expects to finish its evidence halfway through the fourth week.
- The Press