Former Librarian Edwards told a jury how she was woken in the night by a noise while she was visiting her parents without her husband over a bank holiday weekend in May 1998 at their home in Blenheim Close, in the Forest Town area of Mansfield.
Edwards told a jury she got up and went into bedroom where the door was ajar and the light was on, adding: "I saw my father on the floor and my mother standing over him.
"I knew my father was dead. I don't know how I knew, I just knew,
"[My mother] kept saying all of these things. She said she knew of my father's abuse," Edwards said.
"She kept going on and on.
"At some point I lost it. I shot my mother."
A woman accused of burying her parents in their garden after murdering them told a jury of the moment she "lost it" and shot her mother.
Susan Edwards, 56, with husband Christopher, 57, is accused of murdering Patricia and William Wycherley in 1998 and then pretending they were alive for 15 years.
Prosecutors have told Nottingham Crown Court the pair killed the elderly couple at their semi in Mansfield, Nottinghamshire, before burying them in their garden and then raking in £245,000 by making it seem like they were still alive.
The former librarian told the jury she had gone into her parents' bedroom to find her mother standing over her father, who was dead on the floor.
She said she picked up the gun after her mother had put it on a bed and shot Mrs Wycherley who was provoking her with relentless taunts.
Christopher Edwards has told the jury at Nottingham Crown Court that when his wife, Susan Edwards, told him she had shot dead her mother, he wanted to go to the police but agreed not to when she became stressed.
Edwards claims she became agitated and that she said:
We can't. It's matricide. It's my mother. They won't understand.
Christopher Edwards has told the jury at Nottingham Crown Court that when he and his wife went to France last year they never intended to "hide there forever" and that they "could not sustain things anymore".
He says that they eventually returned to the UK because they had run out of money.
More to follow...
A woman accused of murdering her parents and pretending for 15 years that they were still alive faked a decade-long "pen pal" relationship with French actor Gerard Depardieu, her co-accused husband has told a court
Christopher Edwards claimed he only found out during their trial at Nottingham Crown Court that dozens, if not hundreds, of letters from the movie star were fabricated by his wife Susan.
Both Christopher and Susan Edwards deny murder.
Christopher Edwards has told the jury at Nottingham Crown Court that his wife told him how, when she was a teenager, she wrote a letter to the former Liverpool boss Bill Shankly and that she received a reply inviting her to meet him at the Cumberland Hotel in London.
He told the court that Susan Edwards also told him she had correspondence with the actor Gerard Depardieu, but that over the last few days he has come to believe the letters she received were actually written by her.
A man accused of killing an elderly couple & burying them in the back garden has began giving evidence at Nottingham Crown Court.
Christopher Edwards and his wife Susan Edwards are charged with the murders of her parents William & Patricia Wycherley.
Their remains were found buried in the back garden of their former home on Blenheim Close, at Forest Town in Mansfield, last October. Both had been shot twice in the upper body.
Christopher Edwards told the jury that he did not gun down his parents-in-law in cold blood.
When asked by his barrister if he planned - with his wife Susan Edwards - to kill the Wycherley's, he replied "I did not".
The Edwards deny murder. More to follow...
The bodies of William Wycherley and his wife Patricia were wrapped in duvets that each had two bullets in them, a court has heard.
Their daughter, Susan Edwards and her husband Christopher, are accused of murdering the couple 16 years ago and burying their bodies in their back garden in Mansfield.
ITV News Correspondent Ben Chapman, who is at Nottingham Crown Court, reports:
William & Patricia Wycherley's bodies were found wrapped in duvets, lying one on top of the other, under the garden. 2 bullets in each duvet
The woman accused of murdering her parents and burying their bodies in their back garden in 1998 told her husband of the killings a week after the incident over fish and chips, the man told police.
He said the couple then watched the Eurovision Song Contest together before agreeing to bury the bodies the following morning, a court has heard today.
Susan Edwards told police following her arrest last year that she had been staying at her parents' house in May 1998, when she heard her mother shoot her father dead.
She said Patricia Wycherley then admitted having an affair with Christopher Edwards, her husband and co-accused, and that during the argument that ensued she picked up the gun and shot her mother, a court was told.
Patricia and William Wycherley lay undiscovered in their garden in Mansfield for 15 years until last autumn.
A woman sent Christmas cards to relatives of her parents, whom she's accused of murdering, in order to convince people they were still alive, a court has heard.
Susan Edwards told relatives her father and mother were travelling in Ireland. In reality, they had been shot dead eleven years earlier and buried under the garden of their home.
She wrote: "It is as if he's having his second youth. All he speaks of now is travel and travelling ... I cannot really keep up with where he is planning to settle! It is good to see them with such zest."
Susan Edwards is accused, along with her husband, Christopher, of shooting William and Patricia Wycherley to death in 1998, before burying their bodies in their garden.
The court was told that over 15 years they claimed more than £245,000 in the dead couple's name.
They both deny murder, but admit burying the bodies and theft. Susan Edwards also admits the manslaughter of her mother.