NewsCrime Desk

Irish expert to crack cold cases after breakthrough in DNA profiling

Dr David Casey
Dr David Casey

A NEW DNA profiling technique, which finally nabbed the Boston Strangler after half a century, is being used in Ireland for the first time to try to solve cold cases.

The genetic test is currently being employed to crack some of Ireland's most serious unex­plained crimes.

The technology - known as Y-STR DNA profiling - pinpoints male DNA in evidence samples which contain high levels of female DNA, such as in semen samples taken from a female victim in a sexual assault case.

The technique is now employed in the labora­tories at Forensic Science Ireland in Garda HQ at the Phoenix Park.

Forensic scientist Dr David Casey said this cutting-edge analysis has been employed since November in re-testing samples from cold cases.

"We have a team of people in the lab who are looking at these cold cas­es, testing them with the Y-STR profiling to see if they can resolve them.

"Some of the cases would be suspicious deaths or murders. It covers the whole remit of case types that occur. It only came in to case work in Novem­ber last year. There will be samples there from 20 years ago we can look at.

"An Garda Síochána have a cold case review team and we are in com­munication with them regularly about new tech­niques."

The new test has been used most famously to fi­nally confirm the identity of the Boston Strangler three years ago.

Forensic scientists matched DNA taken from the body of 19-year-old Mary O'Sullivan, who was raped and murdered 50 years ago, to suspected killer Albert DeSalvo, who was believed to be responsible for the slew of deaths that terrorised Boston in the 1960s.

DeSalvo admitted to kill­ing Ms Sullivan - believed to be the last victim of the Strangler - and 10 other women in the Boston area between 1962 and 1964, but later recanted.

He wound up in prison on other charges and he was later killed there by another inmate.

In 2013, authorities told how the male DNA testing technique allowed them to test DNA from the scene of Ms Sullivan's death and get a match first with DeSalvo's nephew and later with his exhumed remains, that excluded 99.9 percent of suspects.

Dr Casey added: "As long as the evidence is preserved we can have a look at it. With clothing the Gardai would have a central storage area. With the swabs, we retain them in the lab. Once a sexual assault kit comes in or kits from the scene of a suspicious death, they are retained by ourselves.

"The lab was established in 1975. We could have cold cases dating even further back if the gardai can go back to their central storage area and identify cases.

"There is really no time limit. If we find the evi­dence, it has a major impact. We are actively looking at cold cases with An Garda Síochána."

Dr Casey examined evidence in 1,450 sexual assault cases in Ireland in a new study, which con­cluded that evidence of sperm in victims declines significantly 48 hours after sexual intercourse.

Dr Casey said the new Y-STR testing for male DNA can be employed in the absence of any trace of semen in a sexual assault case where the presence of so much female DNA can mask the DNA of the perpetrator.

He said: "Y-STR profil­ing is profiling of male DNA only. It ignores the female DNA. It is much more sensitive.

"It has improved our ability to get the best fo­rensic evidence in sexual assault cases.

"We can also pick up the male chromosome in male saliva which contains male cells from our perpetrator. It picks up pretty much any type of male DNA."

The national DNA da­tabase, which is up and running over a year, is also proving to be a ma­jor success by making a connection between in­dividuals and 530 crimes - including 359 burglaries and five sexual assaults in its first year.

Dr Casey said the main message to the public from his study is to get medical­ly examined as quickly as possible after a sexual assault.

However, he did express his frustration that their vital forensic work in solving Ire­land's criminal cases is being hampered by conditions in their outdat­ed building in Garda HQ.

"It is a matter of public record that where we are at the mo­ment is not fit for purpose," he said.

"We have been promised the new laboratory and we're waiting for it to begin, but it's been prom­ised for a number of years."