REVEALED: How evil dentist Colin Howell killed his wife and husband of former lover

By Deric Henderson,David Young and Michael McHugh, Press Association

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Colin Howell then drove off with their bodies in the boot of his car and fooled investigating police by stage-managing a scene to make it look as if they had died in a suicide pact, Belfast Crown Court was told.

He kept the secret for almost 20 years before eventually confessing to detectives after losing more than 350,000 in a bid to find missing gold in the Philippines - a project which turned out to be a

scam. Howell, 51, first killed his wife Lesley and later Constable Trevor Buchanan at their homes in Coleraine, in May 1991 when he attached part of a baby's feeding bottle to a garden hose to poison

them with carbon monoxide fumes as they slept.

He ran the hose from a car and killed them after they both fought for their lives. Mrs Howell cried out for her first-bornsonMatthew

when she woke up and realised her life was in peril,

the court heard. Later Howell was involved in a desperate struggle when he gassed Constable Buchanan at his house.

At one stage Howell feared he himself would be overcome by the toxic fumes. Details of the double murder were revealed for the first time at a pre-sentence hearing for Howell, who has pleaded guilty to the murders. The court heard the two bodies were discovered in Mrs Howell's car in a garage behind a house once owned by her father, who had collapsed and died just days earlier.

Crown lawyer Kieran Murphy told Mr Justice Anthony Hart: "This was a meticulous and devious plan and pre-meditated in a manner that might be

described as professional." Howell, of Glebe Road, Castlerock, has already been sentenced to life imprisonment after admitting the two murders. Hewill be told on Friday the minimum term he will have to serve.

His former lover, mother-of-two Hazel Stewart, who remarried after Constable Buchanan's death, has pleaded not guilty and her trial, which is due to begin in early February, is expected to last up to a

month.

The court also heard that two years after he remarried, Howell told his second wife Kyle, an American divorcee with two children, about the

killings, but his admission was never disclosed until January last year,when he confessed all to his church elders who then called in the police.

Howell and Constable Buchanan's wife had resumed their affair when the dentist decided to carry out the murders late on the Saturday night of

May 18 and the early hours of May 19. The first was in his own house where his wife, who had been drinking and taking prescription tablets

because of her distress over the affair, was sleeping in her night-dress on a sofa.

Howell attached the garden hose to the exhaust of the Renault Savanna by using a baby's feeding bottle which he cut in half. He ran it through a utility room and kitchen to where his wife was lying,adistance of about 25 paces.

He then switched on the engine and waited at the living door as the fumes began to seep out just inches from Mrs Howell's face. But she woke up and cried out for her son Matthew, then aged six,whowas sleeping in another room with his sister Lauren, four, and two brothers,Daniel, two, and Johnny, just nine months.

Howell then pulledaduvet over her head, squeezed hard, and pushed the hose into her face with his right hand and held it there until she died.

At one stage he checked her chest to see if she was still breathing.

As relatives of Constable Buchanan looked from the public gallery, Mr Murphy said: "She called out Matthew, his son's name, and he said that memory haunts him."

The court heard that he then dressed his wife in a T-shirt and leggings and carried her to the boot of the car. He placed a blanket over her head and put a bicycle on top of the body. He drove the Renault from his home at Knocklayde Park to the far side of Coleraine where Constable

Buchanan lived with Hazel and their two young children, Andrew and Lisa, at Charnwood Park, just off the Mountsandel Road.

Trevor was asleep in the double bed. Howell drove into the garage and did the same thing with the garden hose - he pulled it through the house and placed it close to the sleeping officer.

But Trevor also woke up to find Howell, who had been standing outside the bedroom door. He also fought for his life, the court heard. They struggled and fell to the floor to face each other.

Howell bumped his head, but managed to trap Trevor's arms inside a quilt and pulled it over his head. He shoved the hose towards his face, and listened as the policeman took his final breaths.

In a statement to the police Howell said: "I pulled the quilt over his head first and with my right hand put the hose to his mouth. I remember him sitting up and I pulled the quilt over him. He saw me."

Howell became dizzy at this point because of the fumes. He ranout of the house to the garden, which backed on to a forest, to catch his breath. He then returned.

Trevor, a scenes-of-crime officer with the Royal Ulster Constabulary, was also dressed. His body was carried outside and placed in the boot beside Lesley's. Mr Justice Hart was told that Howell then drove towards

Castlerock, along the Cranagh Road. But before reaching the seaside village he turned right along the Barmouth Road, close to a railway crossing and nature reserve, where he left his bicycle on a grass verge.

He turned, went back and headed for Castlerock to a row of houses at Cliff Terrace which were also known as the Twelve Apostles. One of them, number six, had been owned by Lesley's father,Harry Clarke,who had collapsed and died at his daughter's home 12 days previously.

It was here, in a small garage at the back of the house, that Howell stage managed the suicides. He reversed in and pulled on a pair of plastic surgical gloves.