Matching DNA can be ‘magic tool’ for detectives

DNA fingerprinting has been hailed as magical tool that can catch criminals and clear the innocent.

Our DNA is a carrier of genetic information.

It can be used in a laboratory technique to establish a link between biological evidence and a suspect.

A DNA sample is taken from a crime scene and compared with a DNA sample from a suspect.

If there is a match then the case may be cracked.

There is now a DNA profile of Baby John found on Cahersiveen beach with the Forensic Science Laboratory in Dublin and it follows a blood test taken from the dead baby 33 years ago.

The task now is to use it to find a relative of Baby John.

But as yet detectives have no known samples with which to test a potential match.

People in Kerry may be asked to volunteer samples.

Prof Seamus Martin, prof of medical genetics in Trinity College, said the whole area has become extremely advanced.

“You need now just a tiny amount that contains the cells of a person.

“These can include skin cells.

“Even if someone left their saliva on the edge of a glass or on a lollipop you can get DNA from it.”

Samples stored in the 1970s can be re-analysed, he said.

The highest match is with parents or siblings.

But DNA matches can also be found with extended blood relatives.

Prof Martin said DNA analysis in the future is going to get so sensitive that just by breathing air in a room we will contaminate it with our DNA, which could be tested.

“It could be possible gardaí go around constantly analysing the air of various places,” he added.

Gardaí are bound by 2014 legislation which has protections for the public in the collection and storage of DNA samples.

A key safeguard is also ensuring that rigorous technique is used to avoid any false results.