A former dentist has told a court how he gassed his first wife and his former lover's husband to death.

Convicted murderer Colin Howell, 51, has already admitted killing his wife Lesley and Trevor Buchanan - the policeman husband of his then mistress Hazel Stewart.

Today he gave evidence at the trial of Stewart, who is accused of the double murder in May 1991.

She was married to Mr Buchanan at the time of the murders and was having an affair with Howell.

She is accused of being part of a joint enterprise to kill her husband and Howell's first wife, but denies the charges.

Giving evidence at Coleraine Crown Court, Colin Howell told the jury that he discussed a plan with Stewart to kill their spouses in May 1991.

He said he gave Stewart tablets to put in her husband's food to ensure he was asleep on the night they were to carry out the killings.

Howell said: "When Hazel accepted the pills I took it that a contract had been signed [to go ahead with the plan]".

He also described to the court how he used a hosepipe to kill his wife with car fumes on the night of his son's second birthday.

He said he put her body in the back of his car and then drove to the Buchanan family home to do the same thing to Mr Buchanan.

He alleges that while he was gassing Mr Buchanan, Stewart was there and expressed concerns that the fumes would leak in to the bedrooms of her sleeping children.

Howell then drove the bodies to a quiet garage behind a cottage and made the scene look like suicide.

He told the court Stewart panicked about being caught but never objected to the principle of killing their spouses.

Howell also told the court why he had confessed to the killings: "I just knew that the time had come that the truth had to be told."

"I was overwhelmed by my conscience from hiding those crimes for such a long time.

"I believed there still were scars that needed to be put right and I wanted to tell the truth, but that was my only motive."

In his first of two days as a Crown witness, Howell recounted how and why his affair with Stewart had developed in 1990.

He claimed he and his wife Lesley had relationship problems before their marriage in 1982 and these got worse as the years passed.

Howell described how his wife "generally got the upper hand" in arguments and that he began to feel insecure, seeking out someone who "approved" of him.

He said he got to know Stewart when she worked as an assistant in the playgroup his children attended.

"She approached me and said she was impressed with the way I was doing my front crawl. That she would like to do it the way I did because she had problems breathing."

He told the court he gave her a few lessons and on the third he recalled running his hand across her stomach.

"She didn't object," he said.

He then apologised and admitted he was not having "innocent thoughts" about her.

She then declared: "Well, I'm not that innocent myself."

The affair then developed into a sexual relationship weeks later when he went round to her house on the pretence of giving her guitar lessons.

Howell - a successful cosmetic dentist who boasted Jordanian royalty among his patients - was jailed for a minimum of 21 years in December.

He is currently incarcerated at Maghaberry prison, Co Antrim.

Source - Yahoo.