Forensics expert ‘had been on medication’ in the witness box

She said in cross-examination that the medication, both prescribed and unprescribed, had made her "weary, tired and confused'' when she was in the witness box in June 2012.

The expert is giving evidence at the trial of Fred McClenaghan (52), from Broad Street, Magherafelt.

He denies murdering his former partner at a Portstewart launderette in March 2012 with a 100-year-old shotgun.

The defendant entered a plea of guilty to manslaughter on the opening day of his trial, but this was rejected by the prosecution who said it was "murder, pure and simple''.

The forensics expert was giving evidence on her fifth day in the witness box at Antrim Crown Court sitting in Belfast.

Under cross-examination by defence QC John McCrudden, the witness agreed that her evidence at this trial contradicted testimony she gave at the previous trial' in 2012.

She admitted that she did not take notes while testing the shotgun in a workshop and also confirmed she had not followed all procedures and protocols on testing the firearm.

The witness confirmed that she had been on sick leave from work at Forensics Science Northern Ireland (FSNI) between January 2012 and June 2012.

She told the jury, sitting with Mr Justice Treacy: "My doctor had advised that I do not take the stand. I was on 10mg of Valium and 30mg of Citalopram.''

It was at this point the witness broke down in tears and proceedings were adjourned for a short period to allow her to compose herself.

Resuming her evidence, the firearms expert told the jury: "I was originally on 20mg of Citalopram and then my doctor increased this to 30mg.

"I also took 20mg of Valium/diazepam on the morning (of her evidence). I was self medicating.''

Mr Justice Treacy asked: "How did you get non prescribed drugs? Diazepam and Valium, are they not prescribed drugs?''

The witness replied: "I had some in the house. My husband had been in an accident and some of his were left over.''

Asked by defence counsel why she was prescribed Citalopram, she said: "For stress and anxiety.''

The counsel asked if the source of her stress was work-related and the witness replied it was a mixture of pressures at work and home.

She said: "It was everything. Eventually everything comes together and that's when people get to the end of their tether.''

Mr McCrudden QC asked if she was aware that an expert, who had formerly worked with her at FSNI, was going to examine the gun while she was on sick leave.

The court heard that the colleague prepared a report in March 2012 in which she said the witness's testing had been done in the "wrong order".

The witness was also asked if she was on medication while giving evidence yesterday and confirmed she was on 20mgs of Citalopram.

"How long have you been on them?'' she was asked.

Witness: "Since I was prescribed it in 2012. I actually want to come off it. I was looking to come off it after this trial.''

After five days in the witness box, trial judge Mr Justice Treacy thanked the witness for her evidence and told her she was free to go.

At hearing.