The final witness for the Clydach murder trial defence has said she saw a serving police officer in the street where an entire family were "massacred," at around the time of the killings.

Nicola Williams told the jury she saw a man in the early hours of the morning close to the home where mother-of-two Mandy Power and her family were murdered in June 1999.

Mr Morris denies all the charges

The court heard that she later identified him as Stephen Lewis, the former husband of Alison Lewis - the couple who were at one time suspects in the case for which builder David Morris is standing trial.

Mr Morris, 40, of Craig Cefn Parc, near Swansea, denies the murders of Mrs Power, 34, her daughters, Katie, ten, and Emily, 8, and her 80-year-old mother, Doris Dawson.

Previously, the jury at Swansea Crown Court had heard that Mr Morris believed the bisexual mother-of-two was "probably" murdered by Mrs Lewis.

The defence claims Stephen Lewis then helped his wife by clearing evidence from the murder scene.

Both were arrested one year after the killings on suspicion of murder and were released without charge after four days of intense police questioning.

Defendant David Morris claims Alison Lewis "probably" killed the family

The second-to-last witness in the defence's case, Louise Pugh, 19, said she posted a borrowed video tape through the letterbox of the Power home hours before the deaths - described by the prosecution as a "massacre" - were discovered.

The same film was later found at the home of Mrs Lewis.

Miss Williams's evidence was that she saw a man wearing a distinctive jacket close to Mrs Power's Kelvin Road address at 0230 BST on the night of the murders.

She said she was returning from Cardiff after a night out when she saw the man, described as about 6ft tall, and slowed down to see if it was someone she knew.

"I slowed down to have a look at him. I had a good look at him but I did not know him," she told the court.

Miss Williams, from Clydach, told the court the man was in his 30s, was walking quite quickly and was dressed in dark trousers and what looked like a shiny, police-style bomber jacket.

The Powers's Kelvin Road home was burnt out in the attack

She said the following day, at lunchtime, she found out about the killings and immediately went to the murder scene to speak to the police.

"It dawned on me that the man I saw could have had something to do with it," she said.

She added that she spoke with a policeman and left her telephone number and later gave a series of witness statements. An e-fit likeness of the man she described was also made.

In September of the following year she was shown a video by the police and told to watch it twice before making any comment.

She then identified Stephen Lewis from the video and told the court today she was "certain" it was the man she had seen on the night of the murders.

Aerobics class

Under cross-examination from Patrick Harrington QC, prosecuting, she denied that the time and the place she had seen the man later identified as Mr Lewis were wrong.

The court also heard that at the time of the murders Miss Williams regularly took aerobics classes at Pontardawe Leisure Centre, which was also used by Mr Lewis.

Miss Williams rejected a suggestion she would have known Mr Lewis from the leisure centre.

On Wednesday the jury is to hear the summing up by the defence and prosecution.