Stephen Cahoon, known to his friends as Stephen Moore, admitted strangling mother-of-four Jean Teresa Quigley, who was 10-weeks pregnant with his son. However, Cahoon of Harvey Street, Derry, who grew up on a farm in Magherafelt, pleaded not guilty to murdering the 30-year-old at her home at Cornshell Fields, Shantallow, Derry on July 26, 2008.

The seven women and five men of the jury had been given the option of reaching a majority verdict of either murder or manslaughter following the two-and-a-half-week trial. However, after almost eight hours deliberating, they told Mr Justice Patrick McCarthy they could not reach an agreement.

The judge told them to write 'disagree' on the issue paper and discharged them from jury service for 10 years. The case was then but back into the court list, with the father-of-one facing retrial here.

Ms Quigley's mother, who found her bruised body, broke down in tears and was comforted by her other four children as she left court. She had discovered lying in a pool of blood on her bed, naked apart from a pair of pink socks.

The Cahoon trial made legal history. Stephen Cahoon was charged under the Criminal Law Jurisdiction Act of 1976 and was given the option of being tried in Dublin or in Northern Ireland. He opted for trial in Dublin and became the first person to be tried before a jury here for an offence under the anti-terrorist legislation.

The 1976 Act was brought in to allow for trials in the Republic for offences committed outside the jurisdiction in Northern Ireland or Great Britain. It has rarely been used and up until now the only cases have been brought before the three-judge, non-jury Special Criminal Court, which deals with terrorist offences.

Last November, Belfast man Gerard Mackin was convicted of murder at the Special Criminal Court under the 1976 Act and jailed for life. He was found guilty of murdering Belfast taxi driver Eddie Burns in the city in 2007.

The trial had heard that the deceased had recently broken up with Cahoon, whom she had begun dating on St Patrick's Day. The court heard that she was shaking the day she told him to leave her house, about two weeks before the killing.

The jury saw text messages she sent him in the days before her death in which she described him as a nutter and told him she wanted him out of her life. However Cahoon went into the witness box and said she could say one thing and mean another.

The accused said he went to Ms Quigley's house about 2 o'clock that Saturday morning to pay her £150 for two dogs they had bought. He told the prosecution he didn't think he needed to ring first, despite her telling him she did not even want to be friends.

He said the taxi driver was mistaken when he said Cahoon had a holdall with him on the way to the house. He claimed he asked the taxi to stop at the end of Ms Quigley's road because he felt sick, not so that he wouldn't be seen, as the prosecution had suggested.

Cahoon said the young mother let him in her two front doors; he could not explain why the internal door was damaged and appeared forced when police arrived that evening.

He said that after he fed their dogs, which he was trying to sell, she told him he could sleep on the couch. He claimed she later said he could sleep with her.

He said she tied him up with handcuffs and some parcel tape and they had sex. He said they had this type of sex about twice a week.

He claimed that after a smoking break, he insisted that it was his turn to tie her up and they had sex again. His phone rang but he didn't answer it, he said.

Cahoon said that afterwards, Ms Quigley asked him to check who was calling. He said that when he gave the name of a female friend, she told him to get out.

He told her he did not want to leave as she had already told him he could spend the night, and that he wanted to stay with her and his baby.

He claimed she began screaming that the child was not his and that she was having an abortion.

"I snapped," he said. "I just grabbed her by the throat. I wanted her to be quiet."

He said he didn't mean to kill her when he pressed down on her neck for about a minute.

"She just riled me up," he said, introducing the defence of provocation, which can reduce murder to manslaughter.

He could not explain why her head, body, arms and legs were covered in bruises.

He denied gagging her with a sock found covered in her saliva. He said he used it after he strangled her to clean the blood and 'frothy stuff' coming out of her mouth before giving her CPR.

He said when the CPR did not work, he 'went for a piss' and left. He blamed panic for his locking her inside the house.

Cahoon booked a taxi from a bus shelter under his friend's name. He was arrested in Donegal Town about 10 days after the killing.