Routine DNA sampling needed to help identify ocean deaths: UCT study

The difficulty in identifying bodies found in oceans has been flagged by a University of Cape Town (UCT) team.

Of the 289 bodies found in the sea, rivers, dams and swimming pools between 2017 and 2021, one in three arrived at the Salt River Mortuary without a name. Of the 289, 26 left the mortuary without a confirmed identity.

This is according to a study led by associate professor Laura Heathfield from UCT’s division of forensic medicine and toxicology.

Urban water sources like baths and pools saw a near-perfect identification success rate of 98.6%, the study found. For ocean cases that figure dropped to 87.2%.

Published in the journal Forensic Science, Medicine and Pathology, the study found that nearly half of the bodies (48.4%) were pulled from the ocean, mostly along the western coastline between Camps Bay and Bloubergstrand.

Ocean cases were the hardest to solve. “Strong currents, marine life and prolonged exposure to water can severely damage deceased bodies, making it difficult to recognise individuals or apply conventional forensic identification methods,” said Heathfield.

Nearly 79% of those recovered were male. More than half the adults were between 18 and 35, which fits global patterns — young men drown more than any other group

When a body enters the sea, it can travel far from where it went in. Currents move it. Marine life damages it. The longer it stays in the water, the harder it becomes to identify.

One of the biggest challenges investigators face is figuring out how long a person has been in the water. For nearly half the cases, that question could not be answered at all. Without knowing that, it becomes much harder to piece together what happened.

Nearly 79% of those recovered were male. More than half the adults were between 18 and 35, which fits global patterns — young men drown more than any other group.

But one detail stood out. Children under three made up about one in 10 cases. Almost all of them were found in swimming pools and bathtubs, not the ocean.

Just over half the deaths were ruled accidental. But 10.4% were classified as homicides. Cape Town has one of the highest murder rates in the world, and the ocean can hide that. Some of these bodies were never meant to be found.

In most cases, identification came down to a family member looking at a face and confirming who it was. That worked 76% of the time.

DNA testing was the next best option. It was only used in 28% of cases and even then, it only led to a confirmed identity about one in three times. “This reflects the difficulty in obtaining DNA profiles from bodies recovered from water, as well as a shortage of reference DNA samples,” said Heathfield.

If you have a missing family member and have never received answers, Heathfield is asking you to come forward and provide a DNA sample for comparison

Part of the problem is resources. Families often have not provided a DNA sample to compare against. South Africa has no national missing persons database so even a good DNA result can hit a dead end.

The study found that nails gave the best results for DNA testing compared to blood, a finding the researchers say has practical implications for how samples are collected at the scene.

The researchers are direct about what needs to happen.

DNA sampling must become routine, not optional. The way waterlogged bodies are handled needs to be standardised. According to researchers, each pathologist presently makes their own decisions which leads to inconsistent results. And the records kept on these cases need to include more detail, such as water temperature and seasonal factors, to help both investigations and drowning prevention.

Most accidental drownings in South Africa happen in summer. Roughly 85% of South Africans cannot swim. Most people in Cape Town live within 30 minutes of the coast. “The risk is structural, not incidental,” the study notes.

UCT’s molecular forensics laboratory is now running a project to DNA-profile unidentified bodies at the Observatory Forensic Pathology Institute in Cape Town.

If you have a missing family member and have never received answers, Heathfield is asking you to come forward and provide a DNA sample for comparison. The laboratory can be contacted via e-mail at mfl@uct.ac.za.

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