Forensic scientist tells double-murder trial about changes to contamination measures

Forensic scientist tells double-murder trial about changes to contamination measures
Sylvia Shields

A forensic scientist has told a murder trial jury that a change of procedure involving the wiping down of the outside of exhibit bags arose out of a contamination incident in Forensic Science Ireland in 2013.

Mark Nash (aged 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 (aged 60) and Mary Callanan (aged 61) between March 6 and March 7, 1997.

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

Today, Dr Linda Williams who was involved in DNA analysis and has worked in the DNA section of Forensic Science Ireland (FSI) since February 2003 was under cross examination by Mr Hugh Hartnett SC for the accused.

Mr Hartnett put it to Dr Williams that things have changed considerably since 1997 and there wasn't the same sensitivity or awareness about contamination in 1997.

Dr Williams replied saying while there was awareness regarding contamination, in that they may have sent samples to other labs, she agreed "contamination measures have changed over the years".

On Thursday the court heard from Dr Williams how she got a DNA profile match to Miss Sylvia Shields, one of the women killed in Grangegorman 18 years ago.

The profile match came from the threads from the jacket belonging to murder accused Mark Nash examined in 2009 but Dr Williams couldn't say from "which set of threads it came from."

Mr Hartnett put it to Dr Williams today how it seems to be the case, that there was no exam carried out looking for traces on the threads so she combined them and got a single result from the threads from the three separate buttons, which Dr Williams agreed with.

"So you can’t say from which thread you got the result?" asked Mr Hartnett.

“Even if tests were done, I would be reluctant to say where it came from” replied Dr Williams.

"It could be from anything like a piece of hair, a skin cell, nor is it possible to say what time it got there or at what stage?" asked Mr Hartnett.

"I can’t say when it got there" replied Dr Williams.

"The same could be said for the particle?" asked Mr Hartnett.

Yesterday Dr Williams told the court she generated Mary Callanan's profile, the second woman killed in Grangegorman, from a "small particle, which was like a small piece of grit" found inside the seam of the right sleeve of a black pin-striped velvet jacket belonging to the accused.

“I can just tell you there is a profile there” said Dr Williams.

Discussing the change of procedures that arose from a contamination incident in FSI in 2013, where two cases that were totally unrelated, were examined on the same surface, in the same room, at the same time, on the same day, Mr Hartnett asked Dr Williams if this "led to a specific change of procedures?"

Dr Williams replied telling Mr Hartnett that FSI "started wiping down the outside of the plastic bags then."

Counsel for the State Mr Brendan Grehan SC called their final witness of the trial, Dr Geraldine O'Donnell who has been employed as a forensic scientist in Forensic Science Ireland since 1992.

Dr O'Donnell told the court she worked as a case worker in the DNA area until 2007. From 2007 up until three weeks ago she was the laboratory quality manager but had now being promoted to the role of Director of DNA in FSI.

Mr Grehan asked Dr O'Donnell what was the procedure in relation to how she approaches the work she does?

"As quality manager I would operate a quality system, where people wear protective clothing, masks, caps, gloves, lab coats, wipe benches, put down paper, do their work in different rooms and change gloves very regularly to avoid contamination, they would be the central core principles to avoid contamination" replied Dr O'Donnell.

Mr Grehan put it to Dr O'Donnell that FSI have a log of contamination events from 2011 onwards?

“We always kept systems but the ethos is we try to improve year on year how we do things, we also monitored how we did things from 2008 but formal event logs began in 2011” said Dr O'Donnell.

“Part and parcel is to monitor the environment and contamination, it gives you information you need in any good quality system to assess the procedures so information is important in a quality system to be able to do that and have confidence to stand over your testing, while no lab can be DNA free, its allows scientists to have confidence in the process" said Dr O'Donnell.

"If a scientist does something wrong or makes a mistake, you want to foster an environment for people to hold up their hands and say I made a mistake” concluded Dr O'Donnell.

Mr Grehan then brought Dr O'Donnell to a contamination case in a "totally different case " in 2013 which was contamination between two separate cases, also known as "case to case contamination".

“It was a scientist working in the lab, no one involved in this case” said Mr Grehan to Dr O'Donnell and he asked her to summarise what occurred.

“The scientist had two cases in the same search room, at the same time, on the same day, he took a sample for DNA processing and when he processed that sample, he found it had a DNA profile that matched a blood stained lamp that had been in the room on the same day” said Dr O'Donnell.

“The two cases were totally unrelated and the lamp was from a totally different case. They had been in the room at the same time and examined on the same surface” Mr Grehan put it to Dr O'Donnell, which she agreed with.

Cross examining Dr O'Donnell, Mr Hugh Hartnett SC for the accused put it to her that she firstly came to the conclusion that the contamination must have taken place in storage but she then found it was in the bench logs.

“If there hadn't been bench logs you might have been in difficulties to discover the truth, as the statements filled out by scientist were grossly incorrect?" asked Mr Hartnett.

"I told him it was poor practice and it was important he got his anti-contamination measures right” replied Dr O'Donnell.

"Without bench logs, the truth would never have been discovered, there would have been confusion and uncertainty” Mr Hartnett told the court.

"Were there bench logs in 1997?" asked Mr Hartnett.

"No" replied Dr O'Donnell.

"So they are there to allow you to carry out quality checks, they are now considered to be an essential part on the monitoring of a lab, as it allows one to carry out the appropriate checks" said Mr Hartnett.

"Just because you don’t have bench logs, doesn't mean you can’t track a case" said Dr O'Donnell.

In the case of best practice of a cold case review, Mr Hartnett told the court, how the use of a separate scientist working independently on the case had been adopted in the Stephen Lawrence murder case in the UK.

"What is being suggested is the use of a scientist outside of the lab, who can bring a fully independent view to the movement of exhibits during that period of time" Mr Hartnett put it to Dr O'Donnell.

Dr O'Donnell said she was of the opinion, that the more opinions you can get the better.

Mr Hartnett put it to Dr O'Donnell that in November 2013, contamination occurred because up to date anti contamination measures were not in place at that stage?

Dr O'Donnell replied saying: "What was not in place was the wiping of the outside of bags."

"And the wiping of bags is a possible cause of contamination" added Mr Hartnett.

The court heard from Dr O'Donnell how contamination events have been logged formally since 2011.

"How many events have you logged?" asked Mr Hartnett.

“In 2011, 14 contamination events, in 2012 it was 22, with new chemistry's it increased to 31” said Dr O'Donnell.

Re examining Dr O'Donnell, Mr Grehan asked about the accreditation of FSI in terms of international bodies?

"We are accredited to 17025, this is the most important for any testing lab to have, as it demonstrates there are technically competent and able to produce accurate and precise results" replied Dr O'Donnell.

Mr Grehan asked Dr O'Donnell if she had any comment to make on a six-week gap between items being examined in the same exam room?

Previously the murder trial jury heard that a jacket belonging to the accused and heavily blood stained clothing and bedding found at the scene were examined in the same room at a laboratory six weeks apart.

"I would consider that after a period of six weeks it would be ok to examine. I would know in UK labs there can be cases where quite a number of exhibits come in and there isn't enough room , to keep all things separate, and you get over that by keeping a time gap. This wouldn't be a new practice" replied Dr O'Donnell.

Mr Hartnett then re-examined adding that the protocol in 2015, is that the same room shouldn't be used for crime material and suspect material and cleaning systems today are totally different.

Mr Grehan then told the jury of six men and five women that this concluded the prosecution's case.

Subsequently Mr Justice Carroll Moran addressed the jury saying a legal issue has now arisen and as indicated by counsel it will take up much of Monday, so there was no point in them being here and asked them to come back on Tuesday morning at 11am, where he hoped they would be in a position to resume the case.

The trial continues.


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