A builder accused of murdering three generations of the same family had sex sessions with one of the victims, Swansea Crown Court has heard.

David Morris, 40, told police he and mother-of-two Mandy Power were having relations, despite the fact that Mr Morris was living with Mrs Power's best friend Mandy Jewell.

I suppose that it could have gone on for years, once here, once there

Defendant David Morris

Mr Morris said both he and Mandy Power were guilt-ridden by two impromptu sex sessions, which of which had both been the "stupidity of the moment".

Mrs Power, her two daughters Katie and Emily, and her 80-year-old mother, Doris Dawson, were found dead at their home in Clydach in June 1999, following what was described in court as a "massacre".

Mr Morris, 40, of Craig Cefn Parc near Clydach, denies all four charges.

Despite the sexual relationship, the court heard Mr Morris told police neither of the couple had attempted to build an affair.

"But I suppose that it could have gone on for years, once here, once there," he said.

Forensic experts found a bath of blood

Earlier in the trial, prosecutor Patrick Harrington QC claimed that Mr Morris had carried out the killings after the mother of two spurned his sexual advances.

He then set fire to the house to conceal his crime, it was claimed.

On Tuesday, the court heard that forensic scientists had failed to find any DNA evidence linking Mr Morris to the murder scene, a jury has heard.

The jury was told that Home Office scientists examined hundreds of items removed from the house where the family members were battered to death.

A further detailed examination of the house was carried out. Again, no evidence was found to link Mr Morris to the scene, apart from a gold chain lying in a pool of blood.

Neither was any incriminating evidence found when scientists examined clothing belonging to him.

David Morris denies four counts of murder

Forensic scientist Claire Galbraith had told the jury that whoever committed the murders either bathed or showered before leaving the murder scene.

She found a bath at the house half full of bloody water, and there was also blood on the shower control unit.

The court was told that divorcee Mrs Power, aged 34, suffered the worst of her injuries in front of her bedridden mother.

Asked to speculate on the sequence of deaths, Mrs Galbraith said she thought Doris Dawson was the first to have been attacked.

Police found a gold necklace lying in a pool of Mrs Power's blood on the bedroom floor, and the prosecution has alleged that the it belonged to Mr Morris.

The trial continues