Forensics expert tells Mark Nash trial he would’ve expected more blood

More blood flakes would’ve been expected on jacket if accused had been present at crime scene

A forensic scientist told a murder trial jury on Friday that he would have expected to see more blood flakes on a jacket belonging to the accused if it had been present at the killing of two women 18 years ago.

Mark Nash (42), who has last addresses at Prussia Street and Clonliffe Road in Dublin, has pleaded not guilty at the Central Criminal Court to the murder of Sylvia Shields (60) and Mary Callanan (61) between March 6th and March 7th, 1997.

The trial has heard the two women were living in sheltered accommodation in a house attached to St Brendan's Psychiatric Hospital in Grangegorman at the time.

Defence counsel Mr Hugh Hartnett SC today called the second and last of his witnesses; Dr Philip Avenele, a doctor of philosophy and forensic scientist who has worked on high profile cases on body fluids and DNA profiling.


Dr Avenele told the court he has been involved in several hundred criminal investigations and cold cases within the forensic world including the Stephen Lawrence murder case and the Coastal Path murders.

Mr Hartnett asked Dr Avenele about his involvement in this case and the examinations he carried out on the material in the laboratory at Forensic Science Ireland.

“Last December I got a phone call from James MacGuill solicitors requesting me to become involved in the case. I received documents from MacGuill solicitors from witnesses outlining their scientific findings in the case and to have a look at them,” said Dr Avenele.

On January 9th 2015 Dr Avenele told the court he visited FSI where he reviewed files and viewed the jacket belonging to the accused for himself.

Dr Avenele told Mr Hartnett he would have expected to have seen more blood flakes on the jacket belonging to the accused if it had been present at the killing eighteen years ago.

Mr Hartnett then put it to Dr Avenele that the “limited material” is of significance? Dr Avenele replied saying: “It is of significance.”

Mr Hartnett later asked Dr Avenele to summarise his findings in the case.

“In summary in my findings I have considered two propositions, the first was that the DNA had been deposited on the jacket or shortly after the murders, the second that the DNA could have been deposited at some time when it was seized by gardai, I was unable to determine which was more likely,” said Dr Avenele.

The trial continues.