A 41-YEAR-OLD Lydney woman has gone on trial for the attempted murder of her neighbour after breaking into the property and allegedly stabbing the victim four times with a large kitchen knife.

At Gloucester Crown Court prosecutor Edd Hetherington explained that during the early hours of May 28, last year, Joanna Mammatt had forced an entry into her neighbour’s home in Lydney and had allegedly stabbed Hannah Gwynn, an off duty police officer, four times in her thigh.

The defence has said it will ask the jury to return a special verdict of not guilty due to insanity.

Mr Hethrington said this was an unusual and sad case and told the jury of nine men and three women, that the two neighbours had known each for around two years after Ms Gwynn had moved in during 2021.

“But in the weeks before this incident Ms Gwynn noticed a decline in Ms Mammatt’s mental health in the brief neighbourly chats that they had been having,” said Mr Hethrington. 

“Ms Mammatt began saying odd things and believed that Ms Gwynn had been placed next door that she and her partner could spy on her.

“Ms Mammatt told Ms Gwynn that she knew that there were secret recording devices in her shed and that a shadowy group was trying to harm her.”

Ms Gwynn became so concerned about her neighbour’s welfare that she reported that matter to relevant bodies as well as raising her concerns with her sergeant at work.

The jury was told that Ms Gwynn did not consider Ms Mammatt to be a threat to others, but felt she needed some mental health support. 

Ms Mammatt was subsequently visited by the police and social services who offered her support over the coming days.

The prosecutor said: “Ms Gwynn was woken up at just before 4am on May 28, last year when she heard the noise of her front gate closing. She initially thought her partner was returning home early after working a late shift. 

“But then she noticed that something was unusual as her dogs were acting oddly, and this motivated her to get out of bed and investigate. Ms Gwynn made her way downstairs and in complete darkness she saw a figure standing at the bottom of the stairs. 

“Ms Mammatt then started screaming at Ms Gwynn telling her you have been trying to cause my family harm. 

‘You killed a doctor’ she said, and ‘You’ve been planning all of this’. 

“It was at this point Ms Gwynn realised that Ms Mammatt had a knife in her hand and when she swung out at Ms Gwynn, who was two steps higher, Ms Mammatt allegedly stabbed her victim in the thigh. It was a deep wound. 

“She pulls the knife back out and plunges it straight back into her thigh again. She allegedly repeated this stabbing gesture twice more. 

“Ms Gwynn reacted by grabbing Ms Mammatt’s wrist and began screaming for help from any passer-by or another neighbour to call the police. She managed to wrestle Ms Mammatt down the hallway to the front door. 

“Ms Gwynn was able to grab her front door keys, but then realised that Ms Mammatt had turned and was attempting to push the knife into Ms Gwynn stomach, but she was able to take evasive action and turn her away. 

“It then appeared to Ms Gwynn that Ms Mammatt was then going to use the knife on herself. Ms Gwynn grabbed at the knife, slicing her finger in the process, and threw it as far as she could into her living room. She was also able to remove an orange life hammer from Ms Mammatt. 

“Lizzy Powell, another neighbour, who had heard the commotion, and had called the police, was outside the property when Ms Gwynn was able to open the front door and evict Ms Mammatt. 

“She grabbed her hair and pulled her down to the floor. Another neighbour Marion Balam also helped restrain Ms Mammatt.

“Ms Gwynn’s initial instincts was to find her handcuffs, but when she realised that she was bleeding badly from her leg and the floor was covered in blood. She called her partner to immediately return home and called an ambulance. Ms Gwynn’s two other neighbours then assisted in first aid until the paramedics arrived. 

The jury heard that Ms Mammatt had climbed in through a downstairs window having forced it open and when the police arrived at the scene, Ms Mammatt was outside her own home and had been spotted putting clothes into her bin. She told the officers she would come peacefully. 

After her arrest Ms Mammatt told officers that she was glad she had done something that would eventually go to court, adding: “I need to tell people what’s happened. I didn’t want to have to do that.”

The jury heard that a blackboard inside Ms Mammatt’s house had various statements on it, including, ‘If you profess to love God, why you killing her?’ and ‘If I die, life itself dies. I don’t want death to win’. 

On scraps of paper Ms Mammatt had written, ‘Joanna is good, very very good. Hannah, next door, is evil, very evil’ and ‘I’m a friendly giant, she is cruel and must be destroyed’. 

Another sheet of paper had another statement, ‘No evil allowed. Everything is private, including me. I turn Hannah off. She gets no enjoyment from hurting me’. 

Mr Hethrington concluding by telling the jury that it was obvious that when Ms Mammatt tried to kill Ms Gwynn, she was suffering from a very significant mental illness at the time. However unusually in this case there could be an additional verdict that the jury could reach, aside from being guilty or not guilty, but not guilty by reason of insanity.

Stephen Donnelly, defending, said: “The issues in this case revolve around the mental health issues of Ms Mammatt, which run parallel with the facts. 

“In relation to the main charge, the defence case is the actions of Ms Mammatt did not amount to attempted murder of Ms Gwynn. The psychiatric evidence is such that the defence would invite the jury to return the special verdict of not guilty by reason of insanity. 

“Even if she did have a knife in her possession without good reason, the defence in light of psychiatric evidence, as this was part of her insanity.”

Ms Mammatt, flanked by three mental health support workers in the dock, denied the attempted murder of Ms Gwynn on May 28, 2023 and possessing a knife in public, without good reason on the same occasion.

The trial continues.