A senior scientist at ESR has told the jury at the Blessie Gotingco murder trial that the male DNA profile on the vaginal swab from Mrs Gotingco showed it was 280 times more likely to have come from the defendant than any other random male New Zealander.
A 28-year-old man with name suppression is accused of Mrs Gotingco's rape and murder, as the trial moves into its final week.
The Crown case is that just before 8pm on May 24, 2014 the defendant deliberately ran Mrs Gotingco down in his car as she walked home along Salisbury Rd from work.
It is alleged he then bundled her into his car and took her back to his home where he raped her, slit her throat and stabbed her to death, before dumping the body at a nearby cemetery.
Mrs Gotingco's body was found two days after the alleged killing and the defendant was charged with committing the murder on May 27.
She said she separated the cells from the vagina and the sperm and the DNA from each cell samples was tested.
"Some of the DNA present in the vaginal swab originated, in my opinion, from the semen," she said.
Amicus of the court Kevin Brosnahan challenged that the sample of the sperm taken from the vaginal swab included carry-over cells and the sperm was a very small sample.
Earlier today, ESR's Fiona Matheson was cross-examined in the High Court at Auckland after giving evidence last week of finding sperm present on intimate swabs taken from the victim's body.
Ms Matheson gave evidence of microscopic sperm heads being present on swabs taken from the body.
But she told the jury there were some issues with those samples, regarding which she emailed the officer in charge of the case.
ESR protocol dictates the end of swabs be cut off after they have been used so the material on them dries and is therefore preserved for analysis.
However, that did not happen when they were collected at post mortem and Ms Matheson had to allow them to dry in the laboratory.
The man charged with the murder of Blessie Gotingco. Photo / Sarah Ivey
Mr Brosnahan suggested that was "sub-standard" and the witness agreed it was not best practice.
"Where you get this increased power and sophistication [in forensic analysis], it heightens the need for extreme care and vigilance to minimise this risk of contamination," the lawyer said.
Mr Brosnahan suggested there were other means by which the defendant's semen could have incidentally got onto the victim's body.
He said it was accepted that Mrs Gotingco had been in the back of the man's car, where there could have been pre-existing stains.
"People have sex in the back of cars; I assume," Ms Matheson said.
Mrs Gotingco's body was eventually found wrapped in the defendant's bedsheet and Mr Brosnahan asked whether it was possible semen from the material transferred to her body from that.
"It's a possible scenario to consider," Ms Matheson said.
Ms Matheson admitted to the court her own bookkeeping in relation to the case was deficient.
"What's obviously not reliable and robust is my note-taking... it doesn't reflect my skills," she said.
During cross-examination Ms Matheson conceded she had used incorrect forms to record data and had used post-it notes when she should have formally recorded findings.
Mr Brosnahan asked her if it was possible she might have mixed up samples from different areas of the body.
"Definitely not," she said.
The lawyer also probed the witness on a "last-minute" lab test of a cervical swab, undertaken only 10 days before trial at the request of the Crown, which eventually indicated the presence semen.
Mr Brosnahan said the testing resulted in 400 pages of notes being disclosed to the defendant's then defence team on the eve of the trial.
