2 days Ago By By Talker News
By Stephen Beech Maggots may help solve rape cases, suggests a new study. Blowfly eggs and larvae can carry crucial evidence - such as sperm - which could help in sexual assault investigations, say scientists. Research shows that blowflies can inadvertently collect and retain DNA evidence from sexual assault crime scenes, making them a potentially powerful tool for forensic investigations.
Forensic entomology is already well-established for its ability to estimate time of death and other details by studying insect activity. But the new study, by researchers at the University of Portsmouth , examined whether insects can carry DNA evidence to identify a sexual offences suspect. The research team say their findings, published in the Journal of Forensic Entomology, could prove "invaluable" in solving complex cases where conventional evidence is scarce or unavailable.
Alexine Clarke, of the University’s School of Criminology and Criminal Justice, said: “I wanted to question whether eggs being laid on a body with semen present could act as a vessel for DNA, which would theoretically allow us to link an offender to the crime. “Although forensic entomology can be used in death investigations to estimate time since death, recovering male offender DNA, attributed to sperm cells, from the gut content of blowflies is relatively new, and this is the first time research in England has looked specifically at sperm cells.” The research team designed an experiment to mimic real-world forensic scenarios.
A small amount of boar semen was applied to the skin of pigs to simulate evidence sometimes found at serious and complex crime scenes. Blowflies were attracted to the decomposing remains and lay hundreds of eggs and larvae. The researchers processed some of the blowfly eggs and younger larvae by washing and freezing them after collection.
Other larvae were left to grow larger and their gut content was examined just before they pupate. They used a specialist technique called "differential extraction" to separate the sperm from piglet skin cells. The samples were then analyzed under a microscope to detect the presence of intact sperm.
Clarke, a lecturer in forensic investigation, said: “In at least 50 percent of the samples, sperm cells were present. "This is an exciting finding because it shows that the blowfly eggs and larvae can retain evidence such as sperm, potentially linking perpetrators to crime scenes.” Dr.
Katherine Brown, Principal Lecturer in Forensic Science, said: “This research builds on existing knowledge of host DNA detection in blowfly and other insect larvae, with the important distinction that we can attribute the DNA to the cell-of-origin; sperm. Not only does this indicate the source of the DNA, but also potential activity, contributing significantly to serious crime and tackling violence against women and girls.” Clarke is now exploring whether a full DNA profile can be obtained from the samples.
Dr. Brown said further research is also necessary to explore how environmental factors and time affect the preservation of such evidence on and within blowflies. She added: “As we expect samples to rapidly degrade, this project is interlinked with our Single-Cell DNA Identification (SCAnDI) work to maximize chances of obtaining a full DNA profile.
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