A 72-year-old man who prosecutors claimed had "confessed" to his cats has been cleared of killing his partner.
David Henton had known Joyce Sutton for 32 years
David Henton of Neath denied the murder and the manslaughter of Joyce Sutton, 65, who was found in her bed in 2006.
Secret police recordings showed him telling his cats he hit her, a Swansea Crown Court jury was told.
But his defence said the tapes could be interpreted differently. South Wales Police have not yet decided whether to reopen the inquiry into her death.
There were gasps from the public gallery as the forewoman of the jury declared that Mr Henton was not guilty of murder and the alternative charge of manslaughter.
Mr Justice Grigson thanked the jury of nine women and three men for their patience during the 41 days of the trial.
Before Mr Henton left the court building he was embraced by members of the jury, who had taken nearly 12 hours to reach their verdicts.
Mr Henton declined to comment before he was driven away, and as he was led from court by his solicitors, the family of Mrs Sutton hurled abuse at him.
Det Sgt Dave Peart of South Wales Police said: "We acknowledge the not guilty verdict at Swansea Crown Court earlier today.
"Our thoughts are with the family of Joyce Sutton. They can be assured that we will continue to support them where we can."
Police arrested David Henton a year after Mrs Sutton's murder
He added: "No decision has yet been made as to whether the case will be reopened."
Mr Henton said he found Mrs Sutton dead after discovering the back door window of the property had been smashed. He then called the police.
He was charged after detectives secretly recorded largely solitary conversations with his cats Twinkie and Pudsey in January 2007, almost a year after Mrs Sutton's death.
The prosecution and defence team had argued over the interpretation of the recordings.
Excerpts the prosecution claimed illustrated his guilt such as "I hit my Joyce", were interpreted by the defence as "I miss my Joyce".
The prosecution claimed microscopic glass particles from the broken window of Mrs Sutton's home were on Mr Henton's clothes and car mats.
Darren Sutton was jailed for rape during his mother's murder inquiry
But police admitted in court that evidence bags used to gather the clothes were not sealed straight away which was "not good practice".
Mr Henton had told the court he had known Mrs Sutton, a grandmother, for 32 years and he had never hit her or raised a hand to her.
He told jurors any concerns would be talked through by the couple and that his time with her were the "best years of his life".
He had nursed her when, in the latter part of her life, she developed depression and refused to get out of bed.
He also told the jury how Mrs Sutton's son Darren had borrowed several thousand pounds from him but never repaid the money.
Mr Henton described how he had been called over by Mrs Sutton because her son was there in a temper and he had found him with a knife in his hand in front of his mother.
After trying to talk him into leaving the house he told the court there had been a struggle.
Earlier in the trial, Mr Sutton denied murdering his mother while under cross-examination by Mr Henton's defence barrister.
The court was told he was arrested on suspicion of the murder but the investigation was then dropped.
During the murder inquiry Mr Sutton was arrested for rape and jailed, the court was told.