Significant advances in DNA technology over the past three decades have made it possible to prove that Joanne Hayes was not the mother of Baby John, who was found dead on Cahersiveen beach in Co Kerry in April 1984.
However, checks so far made against the State’s National DNA Database, which was set up in 2015, have shown that no one currently registered has been matched as being related to the baby.
In a newspaper column in April 2014, one of the leading investigators in the case, the now-retired detective Gerry O’Carroll, called for DNA tests to be carried out.
“The only way to get to the truth of the Kerry Babies mystery is to exhume both infants and subject tissue samples to DNA analysis. This would prove, I believe, that Ms Hayes was the mother of both babies,” he wrote then.
Following the discovery on the beach, Dr Louise McKenna of what was then known as the State Forensic Science Laboratory took a sample of blood – the sample shown to be type A.
However, deoxyribonucleic acid, or DNA-testing, from which a person’s unique genetic profile can be determined, was not then available. Through it a person’s parentage can be determined with fingerprint accuracy.
Late last year Dr Geraldine O'Donnell, the director of DNA at Forensic Science Ireland – the successor institution to the laboratory – re-examined the blood sample which had been dried at room temperature and frozen.
“The practice at the time was that we would have transferred some of the blood [of the Cahersiveen baby] on to a piece of cotton cloth, stapled to a piece of cardboard, to keep in anticipation of technical developments,” she explained.
DNA profiling has become significantly more sensitive, she added: “Years ago you’d need a sample about the size of a 20 pence coin. Now all you need is a sample that can’t even be seen with the naked eye.”
DNA profiling allows for certitude when determining the parentage of an individual because DNA is inherited directly from parent to child, and somewhat less certitude in determining a sibling relationship.
Meanwhile, statistical methodology and analysis has improved since the Kerry Babies case. “Initially it was just parent to child. Now you are better able to establish relations between siblings,” said O’Donnell.
“Once the relationship goes beyond siblings into, say, cousins, the relationship is diluted and the comparison is less certain. The certitude is reduced quite significantly [between cousins] to the extent that it wouldn’t be a useful comparison.”