Semen stains may last years
DNA found on Charlene Makaza's clothing and bedding required caution, a Crown witness has advised the Gwaze trial.
The High Court in Christchurch is hearing evidence in the trial of George Gwaze, 60, a former vet in Zimbabwe, who is charged with violating and murdering 10-year-old Charlene, his niece, in her bed in the family home in Bryndwr, Christchurch.
The Crown contends Charlene died from organ damage caused by suffocation.
Gwaze, who, with his wife, had adopted Charlene and her sister Charmaine when their parents died in Zimbabwe, allegedly injured Charlene in a violent attack on January 5-6, 2007. She died on January 7 in Christchurch Hospital.
Institute of Environmental Science and Research (ESR) scientist Susan Vintiner, a DNA profile expert, told the court today she had found DNA from the accused's sperm on Charlene's underpants and bedclothes.
Sperm could have transferred to Charlene's garments from semen-stained clothing through the laundering process in several ways.
The least likely, in her opinion, was through a machine wash, but other mechanisms were through handwashing and clothing with wet stains lying on other clothes about to be washed.
If the underwear of a sexually active male was washed with the clothes of others in the household, a real possibility existed semen-soiled underpants would transfer semen to other clothes, Vintiner said.
If the soiled underpants were cotton, 46 per cent of the sperm would still be on the garment after a machine wash, and the average ejaculate contained 250 million sperm, she said.
Clothes needed to be washed several times in a hot wash before sperm could be reduced to a non-detectable level.
The results of the ESR tests of Charlene's clothing and bedding therefore needed to be treated with caution, she said.
Science was not able to say how the semen was deposited, she said. Semen stains if kept in a dry environment could last for several years.
In earlier evidence, Vintiner told the court Charlene's pink underpants were tested after they were found washed in the washing machine.
She had found sperm in the crotch area of the underpants which corresponded to the accused.
The sperm fraction tested was at least 10 million million times more likely to have come from Gwaze than the rest of the population, she said.
Two pairs of Charlene's underpants found unwashed on the laundry floor also showed traces of Gwaze's DNA, she said. Neither exhibited sperm but sperm fractions from the underpants had DNA corresponding with Gwaze.
Traces of semen found on Charlene's skirt, which had been washed, were also matched to the accused but not as strongly as the underwear stains. One fraction was 5000 million times more likely to come from DNA from Gwaze, she said.
The sheet from Charlene's bed, which was washed, was cut into 63 sections and three showed the presence of sperm. Tests showed the DNA from the sperm fractions was 200,000 million million times more likely to come from Gwaze, she said.
In other evidence, Simon Nadel, a paediatric intensive-care specialist at St Mary's Hospital in London, giving evidence for the defence by video link, said his hospital had the biggest number of HIV children in Britain.
He said Charlene had probably died of shock caused by an infection or toxins released into her blood from a colonisation of bacteria such as staphylococcus.
When she arrived at hospital, Charlene had presented with several signs of septic shock including low blood pressure, and her skin was cold, he said.
HIV children sometimes developed abnormal reactions to sudden infections and were more likely to get widespread infection. Shock, he said, could kill within hours.
It was harder to reverse Charlene's condition because she had presented with advanced septic shock, and although her low blood pressure responded to treatment initially, it returned.
Although the pathogen that could have caused the infection had not been identified, that was not uncommon in these cases.
He did not agree with Charlene's intensive-care doctor, who ruled out shock as the cause of death because she believed Charlene had a low blood volume.
He disagreed with the doctor's interpretation of Charlene's clinical signs.
In cross-examination, Nadel agreed Charlene's low blood pressure could have been due to asphyxia as could her temperature vacillations.
He said Charlene's clinical signs on January 6 could have been the result of asphyxia or some other event that deprived her of oxygen.
Charlene had presented with symptoms typical of shock but not of asphyxia, he said.
He agreed the degree of lung damage Charlene had would not have caused a sudden oxygen-deprivation event.
The trial started its fourth week today.