A police officer has described his shock at discovering his wife had been having an intense affair with a woman who was murdered along with her family.

Sergeant Stephen Lewis, 35, told Swansea Crown Court that his "life had collapsed around him" after Alison Lewis revealed the relationship - just hours after Mandy Power, her mother and two daughters were found dead.

Stephen Lewis was shocked by the affair

Mrs Power, 34, her children Katie, 10, Emily, eight, and grandmother Doris Dawson, 80, were bludgeoned to death with an iron bar in their home at Clydach, near Swansea, in June 1999.

Scrap merchant David Morris, 39, of Craigcefnparc, Clydach, denies four charges of murder.

The prosecution claims he murdered Mrs Power when she rejected his sexual advances.

Mr Lewis learned of the affair when detectives from South Wales Police interviewed Mrs Lewis about the relationship on the day of the murders.

Officers had told Mrs Lewis: "Tell your husband about it or we will."

The court also heard how the couple were arrested almost a year later on suspicion of the murders and attempting to pervert the course of justice.

Mr Lewis's brother, Inspector Stuart Lewis, was also arrested. All three were released without charge.

The family's burned-out house in Kelvin Road

Stephen Lewis said that within a month of the revelations about his wife's affair, he had packed her belongings in bin bags and filed for divorce.

The jury was told that Mrs Lewis had often visited Mrs Power's home in Kelvin Road, Clydach, and would spend the night there when her husband worked late shifts.

Mr Lewis described a conversation with Mrs Power the day before she died, in which she talked of alleged threats made by her former husband, Michael Power.

After hearing of the murders, Mr Lewis telephoned colleagues with the information.

Speaking about the new of his wife's lesbian affair, the told the court: "I just could not believe it. I was in a state of shock. My God, my kids were supposed to be there for Sunday lunch.

David Morris denies four counts of murder

"My kids could have been in the house if I'd been working nights."

Confirmation of the murders came in a phone call from Mrs Lewis: "The first thing she said was 'It's true - they are all dead'."

"She was hysterical. She was at the scene and I said go home and I will be there now."

Earlier in the trial, Mrs Lewis told of her love for the murder victims.

Mrs Lewis has described how she began an intimate and passionate relationship with Mrs Powers, only two weeks after the couple met at a tarot cards evening.

Gold necklace

She accused South Wales Police of "torturing her with grief" after she was accused of the murders.

On Tuesday, two witnesses told the murder trial they saw David Morris wearing a gold necklace similar to one found at the scene of the murders.

The jury has already been told that Mr Morris admitted the necklace was "probably" his days before the case opened last month.

The trial at Swansea Crown Court is continuing - minus one of its panel of jurors who suffered a stroke at the weekend.