The jury in the trial of 44-year-old Stephen McKinney is to view the hire cruiser from which he claims his wife Lu Na slipped and fell, but from which the prosecution say he "caused her to enter the water".

Madam Justice McBridge told the jury of eight men and four women they would be bussed from Dungannon Crown Court today (Thursday) to see the Lough Erne cruiser Nobel Cadet for themselves.

The hire boat is moored at the jetty at Enniskillen PSNI station. Once there the jury will be able to get a fuller understanding of the boat and its layout.

McKinney, with an address in Castletown Square, Fintona, but living in Convoy, Donegal at the time denies murdering his 35-year-old wife who allegedly drowned during the family boating trip in April 2017.

On Wednesday his trial heard further evidence of the possible affect the sleeping tablet Zopiclone may have had on the mother of two at the time of her suspected drowning off the western side of Devenish Island where the family had moored the cruiser.

The trial, now in its fifth week has already heard that McKinney told police Lu Na was taking the drug for insomnia. He admitted buying the drug over the internet and did not know why he and his wife had not gone to their doctor.

Traces of the sleeping draft was the only drug detected during a screening of a blood sample taken from Lu Na for toxins. Northern Ireland's State Pathologist, Dr. Alastair Bentley has already told the trial the level found was only slightly above therapeutic dosage.

On Wednesday, a pharmaceutical professor said the standard dose of 7.5mg tablets was designed to be absorbed fairly rapidly into the bloodstream, acting on nerve cell receptors by changing their function and decreasing excitability.

These receptors are spread around the nervous system, especially the brain, where one particular part is crucial for Zopiclone to regulate how awake a person is. Once there is sufficient loss of excitability, sedation and sleep can result.

"There is a decrease in the level of anxiety. Zopiclone starts and maintains sleep, with normal predictions of seven hours," explained the professor.

Based on the level of the drug found in the screening, the professor said she had taken "at least two 7.5 mg tablets on the evening before. However, considering some level of post mortem loss almost certainty occurred, it is likely more that two tablets were ingested."

He said Zopiclone effects are not influenced by gender but race could have issues around elimination, as: "Very often drugs are similarly absorbed but there are differences around metabolism."

Under cross-examination from defence QC Martin O'Rourke, the professor said he could not exclude the possibility Mrs. McKinney may have developed a tolerance to Zopiclone, as this would vary per person.

The expert also accepted he could not "rule out" the possibility that Mrs. McKinney may not have awoken upon entering the water, according to the evidence of another medical specialist, regardless of whether she had taken one or two of the sleeping tablets.

At hearing.