Rajinder, 35, is on trial before the High Court at Dunedin, accused of stabbing 27-year-old Gurjit Singh to death and partially decapitated him.
The victim’s body was found outside his Liberton home in January last year when friends became concerned the victim was not responding to messages and phone calls.
Defence co-counsel Katy Barker stressed DNA evidence could never definitively identify a single person.
"We’re only talking about probabilities and likelihoods, we’re not talking about certainties," she said.
Yesterday, New Zealand Institute for Public Health and Forensic Science’s Kate Stevenson concurred.
But she spoke of several blood samples taken from in and around the victim’s home which were 500,000 million times more likely to be attributable to Rajinder than a random New Zealander.
It provided "extremely strong support" for the proposition the DNA belonged to the defendant, she said.
Tested blood samples were from the road outside Mr Singh’s home, the pavement beside it, the carpet in his dining room, the back of a curtain and a surface between doors within the home.
Ms Stevenson also analysed two blood stains from the ceiling upholstery of Rajinder’s Toyota Prius, which likely contained the DNA of both the defendant and the victim.
The sample was 5000 million times more likely to feature Mr Singh’s DNA than someone selected at random, she told the jury.
Ms Barker, though, noted the major component of the mixed sample belonged to Rajinder.
She asked whether the result of the scientific testing could have come from the defendant’s blood combined with DNA deposited perhaps by a tool Mr Singh had used coming into contact with the vehicle’s ceiling.
Ms Robertson could not rule out the possibility but said the indirect deposit of DNA from one item to another depended on elements of time and friction.
There were inherent limitations with such scientific analysis, Ms Barker highlighted.
Forensic testing could not identify what type of cells had been deposited — whether it was blood, skin, sweat or another — nor could it determine how the DNA had got to that location or how long it had been there.
The witness agreed.
The court earlier heard from a forensic pathologist that when the victim’s body was examined, hairs were found in his hand.
Ms Stevenson said the analysis of one such hair also provided extremely strong support for the hypothesis it came from Rajinder.
There were also findings of mixed DNA results from some samples.
Blood spots on the sofa in the lounge and stains on walls were 10 million times more likely to be from Rajinder and Mr Singh than another random duo, the court heard.
Another forensic scientist, Gary Gillespie, who examined numerous areas at the crime scene, also gave evidence yesterday.
He told the jury he was tasked with comparing bloody partial footprints at the scene with a pair of shoes thought to belong to Rajinder.
Mr Gillespie assessed prints on Mr Singh’s deck and on fragments of glass outside the house as providing, at best, "moderate support" for the Crown case.
He noted parallel lines on the shoe sole that appeared to match impressions at the scene, but counsel Anne Stevens KC argued it was a common design and showed the witness footage of armed police walking through the shards as they initially cleared the scene.
"There would be other shoes out there with similar lines on them," Mr Gillesipie acknowledged.
He told jurors he had tested for blood on the shoes, but the results were "inconclusive".
A verdict is expected this week.
rob.kidd@odt.co.nz , Court reporter
