Key Takeaways:
- Rajwinder Singh, the accused, is 3.7 billion times more likely to have contributed to a DNA sample found on a stick at Toyah Cordingley’s burial site.
- Forensic testing of DNA samples collected by police during their investigation into Ms Cordingley’s death has linked Mr Singh to the crime scene.
- Mr Singh has pleaded not guilty to the 2018 murder of Toyah Cordingley.
- The trial has heard evidence about the concept of an "adventitious match", which refers to a situation where a true non-contributor to a DNA profile gives a likelihood ratio supporting contribution.
- The court has also heard that washing and detergents can remove DNA, which could impact the ability to find DNA on items.
Introduction to the Case
The trial of Rajwinder Singh, accused of the murder of 24-year-old Toyah Cordingley, has begun hearing evidence about forensic testing of DNA samples collected by police during their investigation into Ms Cordingley’s death. Ms Cordingley was found buried beneath sand at Wangetti beach in Far North Queensland in October 2018. Mr Singh, a 41-year-old former nurse, has pleaded not guilty to the crime. The prosecution has presented evidence that links Mr Singh to the crime scene, including DNA samples found on a stick and bark at the burial site.
Forensic Evidence
Forensic scientist Angelina Keller told the court that it was 3.7 billion times more likely than not that Mr Singh had contributed DNA to a two-person mixture found on a stick at Ms Cordingley’s burial site. This suggests that Mr Singh’s DNA was present at the crime scene, and that he is a strong suspect in the case. Additionally, Ms Cordingley was more than 100 billion times more likely to have been the other contributor to that mixture, which further supports the prosecution’s case. The court also heard that Mr Singh was 580 million times more likely to have contributed to one sample from some bark at the gravesite, and 42 million times more likely to have contributed to another DNA sample on the bark.
DNA Analysis
Ms Keller explained that DNA analysis is a complex process that requires careful interpretation of the results. She noted that while the results can suggest a likelihood of contribution, they cannot provide absolute certainty. The court heard that the reference samples used in the analysis included DNA from 91 different people, including Ms Cordingley, Mr Singh, and their relatives, as well as police officers, Wangetti locals, and other individuals who were investigated during the course of the inquiry. The results of the DNA analysis have been presented as likelihood ratios, which indicate the probability of a particular individual contributing to a DNA sample.
Inconclusive Results
The court also heard about some inconclusive results, including a DNA sample taken from a tape lift of the stick, which was 4,100 times more likely to have had a contribution from the accused. However, other incomplete two-person mixtures found on the stick and logs at the gravesite were less conclusive. Ms Keller explained that the likelihood ratio will be lower if there is limited information to compare to. The court also heard that Mr Singh was unlikely to have contributed DNA to the multiple-person mixtures found on the lead and collar of Ms Cordingley’s dog, Indie.
Additional Evidence
The jury also heard forensic examination results for the lead and collar of Ms Cordingley’s dog Indie, which was found tied to a tree at the beach. Mr Heidenreich, Ms Cordingley’s partner, was greater than 100 billion times more likely to have contributed to the DNA mixture found on the lead and collar. The court also heard that Ms Cordingley’s parents, Troy Cordingley and Vanessa Gardiner, who gave evidence about their efforts to untie Indie from the tree, also returned high likelihood ratios. Furthermore, the court heard about a two-person DNA mixture taken from Ms Cordingley’s hand, which accounted for 99 per cent of the DNA sample, while 1 per cent of it was the DNA of a male.
Male DNA from Fingernails
The court heard that some samples of male DNA from Ms Cordingley’s fingernails were forwarded to New Zealand for specialist Y-chromosome testing. The results of this testing have not yet been presented in court. The court also heard about the concept of an "adventitious match", which refers to a situation where a true non-contributor to a DNA profile gives a likelihood ratio supporting contribution. Ms Keller explained that this can occur when a person’s DNA is present on an item, but they did not actually contribute to the DNA sample.
Washing and DNA
The court also heard about the effects of washing and detergents on the ability to find DNA. Ms Keller explained that any sort of washing can remove DNA, whether it is washing your hand or an item of clothing. This could impact the ability to find DNA on items, and may explain why some of the results were inconclusive. The court also heard that the top Mr Heidenreich wore on the day Ms Cordingley was killed was examined, and the court heard DNA from bloodstains on the shirt was determined to be his.
Cross-Examination
In cross-examination, defence barrister Kate Juhasz asked whether some of the less conclusive results could be explained by the presence of an unknown person’s DNA. Ms Keller replied that this was one possible explanation, but that she could never say for sure because of the limited amount of information in the profile. The cross-examination is due to continue on Monday, and the trial is expected to continue for several more days. The prosecution will likely present additional evidence and witnesses, and the defence will have the opportunity to present their case and challenge the prosecution’s evidence. Ultimately, the jury will have to weigh the evidence and decide whether Mr Singh is guilty of the murder of Toyah Cordingley.