Barry Rogers and Penny John have been jailed for life for the murder of Betty Guy.

Each must serve a minimum of 11 years before being allowed to apply for parole.

Mrs Guy "loved life" and "loved a little giggle", her daughter Lorraine Matthews has said in a victim impact statement.

The statement read by Jim Davis, for the prosecution, at Swansea Crown Court, said: "We grieved once after her death and now we have to go through a different kind of grief."

Ms Matthews said she was "shocked that a member of my own family is capable of committing such a despicable act on an old lady".

She added: "My mother was in no way ill enough to warrant a mercy (killing).

"I had spoken to her doctor some months before and was reassured of her health... I find it difficult to come to terms with the fact that her life ended before it should have naturally."

Christopher Henley, QC, for Barry Rogers, said the "only way of explaining what happened is as a mercy killing".

He said Rogers loved Mrs Guy "deeply and truly".

"There's no direct evidence of this but there appears to be a solid basis to believe that Betty Guy was a participant in discussions about what happened," he added.

Mr Henley urged the court to act with "a degree of compassion".

Sentencing Rogers and John, Mr Justice Lewis said they committed the murder "on a belief, a misguided belief, held by each of you that the murder was an act of mercy".

He said: "Mrs Guy was not terminally ill.

"She did not have any form of cancer. Mrs Guy had mobility problems but she was not bed-bound.

"She was in pain and had been prescribed a painkiller but there's no evidence at all to suggest that Mrs Guy was suffering unbearable pain.

"You did not therefore kill Mrs Guy because she had, or you believed she had, a terminal illness.

"Again this was not a case where Mrs Guy was suffering or you believed she was suffering in unbearable pain and you wanted to bring that pain to an end... you believed Mrs Guy was old and ill and wanted to die and you believed that you should end her life.

Mr Justice Lewis said Rogers and John had both agreed to end the life of Mrs Guy.

He said: "You each had your role to play.

"You, Ms John, decided that the time had come to kill your mother.

"You arranged for your son to come and carry out the killing, you gave your mother drugs, intending to sedate her.

"You, Barry Rogers, were the one to place the pillow over Mrs Guy's face and to suffocate her."

Mr Justice Lewis said Mrs Guy was a "cheerful, lively and well-liked person".

Nadine Radford, QC, for John, said her client suffered from PTSD as a result of an "extremely abusive, extremely violent" relationship of 22 years with her "first love" who she met aged 16.

Ms Radford said prison would be more difficult for John because of her condition.

Of the reasons for the killing, she said: "There's no motive for this, there's no motive whatsoever.

"There's no question there was some sort of violent motive... there's no financial motive, quite the contrary, there's every emotional reason for it to go the other way."

Ms Radford urged the court to conclude that Mrs Guy's death may have been a killing based on "care and love".