Penelope John used her own sleeping tablets to try and kill her mother Betty Guy, a jury heard today (Wednesday).

And when that didn't work her son Barry Rogers "finished off his grandmother" by placing a pillow over her face, it was alleged.

A jury at Swansea crown court heard that the couple were later secretly tape recorded talking about John crushing tablets of Zopiclone and giving them to her mother in whiskey.

But, said Paul Lewis QC, prosecuting, Mrs Guy had never been prescribed Zopiclone - but John had.

The prosecution allege that John, aged 50, of Union Terrace, St Dogmaels, and Rogers, 33, of High Street, Fishguard, had decided "it was time for 84 year-old Mrs Guy to go."

They deny murdering Mrs Guy on November 7, 2011, at her home in Hillcroft, Johnston.

Mr Lewis said: "It may well be that she was unwell, elderly and frail. But the law still does not permit the killing of one person by another.

"We submit that what the defendants did, and whatever their motivation, was wholly unlawful and each of them is therefore guilty of her murder."

The jury heard today from Mary Collier, a close friend of Ms Guy who lived five minutes walk from her home and who had a key to her two bedroom bungalow.

She said she worked two days a week with Mrs Guy in a charity shop in Johnston.

Mrs Collier said about 9pm on November 6 she called in on Mrs Guy, a former nurse, and found her ill and in bed.

"She said she had had enough and wanted to go. I had never heard her say anything like that before. She was a lovely woman, full of life."

Mrs Collier telephoned John who said she would drive to Johnston immediately and she returned to her own home.

In the early hours of the following morning John telephoned her to say Mrs Guy had died.

Mrs Collier returned to the house and a police officer was already there.

The prosecution claim that after arriving in Johnston John had telephoned Rogers, who was then living in Frome in Somerset with his partner Rhianne Morris.

Miss Morris later told police she heard Rogers say to John, "It's time, is it?"

Rogers then drove to Johnston and, according to the prosecution, he and his mother put into action their plan to end Mrs Guy's life.

Mr Lewis said at first Mrs Guy's death was put down to natural causes and her body was cremated soon afterwards.

But in the following years, he alleged, Rogers made a series of confessions to several people.

After their initial arrest they had been granted police bail on the condition that Rogers lived with his mother in St Dogmaels.

By then officers had bugged the house and John was tape recorded saying to Rogers, "No..I can't remember. Did I text you when I said I crushed Diazepam up and I crushed Zopiclone up and I put it in her (indecipherable)."

Mr Lewis said the pair had become concerned that they had sent each other text messages which the police might be able to recover.

The trial continues.