A man has been found guilty of murder after stabbing a woman to death in a park hours after he warned he would kill a stranger if he was not sectioned.

Cameron Davis fatally attacked 74-year-old Lorna England as she walked home through Ludwell Valley Park in the Wonford area of Exeter, Devon, on the afternoon of February 18 last year.

The 31-year-old had pleaded guilty to a charge of manslaughter by diminished responsibility but was found guilty of murder at Exeter Crown Court on Tuesday.

The judge, Mrs Justice Stacey, told Davis: “You are going to be sentenced for the offence of murder, for which you know that there must be a life sentence, and my task will be to decide what the minimum sentence will be.”

Davis will be sentenced on Thursday.

Addressing the jury, the judge said she hoped the verdict would bring some sense of “comfort and closure” to Mrs England’s family, describing it as an “awful, awful case”.

“This has been one of the most shocking and brutal killings – the killing of a member of the public walking through a park by a complete stranger taps into very deep-seated, human fears,” she said.

“The tragedy for the England family and their grief is unimaginable.”

She praised jurors for their dedication to the case, saying it was full of complex medical evidence, with 17 health experts providing evidence.

Ms England’s family said they were “relieved” that Davis would be in prison, saying he had “ripped our family apart and broken our hearts”.

In a statement released through Devon and Cornwall Police, the family said: “Our family has been devastated by the brutal murder of our much-loved Lorna.

“We have been tormented by the violence, pain and suffering inflicted by Cameron Davis on Lorna from such a mindless and brutal knife attack.

“We will never be able to come to terms with losing Lorna in this truly horrific and evil way.

“Every day we are tortured and tormented as we constantly relive in our heads what Lorna endured prior and during the attack, what she had to go through, what she saw, heard and experienced that day.”

The family said they may never know or understand the reasons Davis attacked a “defenceless, kind and beautiful lady”.

They described Davis as an “angry and manipulative liar” and hoped he would never be considered for release back into the community.

“Life without Lorna is lonely and empty,” they added.

“The family home misses her presence, her love, her laughter and her voice.

“There’s a massive void in our lives now, which has changed forever. This has had a profound and lasting impact on all of her family and friends.

“Every single second of every day we miss Lorna and are living a nightmare.”

Senior investigating officer, Detective Inspector Dave Egan, from the major crime investigation team said: “This was a brutal assault on an innocent woman.

“For reasons known only to Davis, he launched this unprovoked attack on Lorna as she walked home on a Saturday afternoon.

“His pleas to manslaughter were not accepted by the team and we are pleased that the jury reached this verdict today.”

He said Davis went out intent on causing harm that afternoon and he believed it could have been anyone he attacked, and only he would know the reason why he attacked Ms England.

Mr Egan added: “She should have been safe and could never have foreseen what was about to happen.

“It is clear from speaking to Lorna’s family that she was very much loved, and her death has left a huge void in the lives of all who knew her.

“My heartfelt sympathies go out to the family and friends of Lorna who have shown nothing but courage and dignity throughout this trial.”

At a previous hearing, Joanna Martin KC, prosecuting, told the court Mrs England had left home, where David, her husband of 52 years, remained, to walk to buy flour from a Lidl supermarket and was returning when she was attacked.

The jury heard that Davis, who did not know Mrs England, stabbed her twice, once across her neck and once to her chest to a depth of nearly 5in (12cm). Mrs England also suffered defensive injuries to her hand.

The court was told that Davis was living in temporary accommodation provided by a housing association, having been homeless in Exeter when he moved there from Bournemouth.

On January 23, he asked to talk to his support workers because his mental health was deteriorating, saying he would either hurt himself or someone else.

He was assessed by two psychiatrists on January 28, who both decided he did not need to be sectioned.

Davis began expressing his love for his support worker between February 9 and 16 and was seen by the mental health team, who decided he did not need to be sectioned.

He was then given seven days’ notice to leave his accommodation.

Ms Martin said Davis called police at 4.41am on the morning of February 18 – the day he attacked Mrs England – and threatened to take his own life in a fire at his accommodation unless he was arrested.

Paramedics and police attended the property, where they found Davis sitting on the pavement outside.

“He said he was going to kill someone if he was discharged that day,” Ms Martin told the court.

“He said he had committed other crimes in the past and always got away with it. He repeated that if he was discharged, he would kill a random person.”

Davis was taken to the Royal Devon and Exeter Hospital, where he was told that if he did anything it would be a pre-meditated crime.

Two psychiatrists discussed whether to section Davis and decided that he did not need to be admitted to hospital.

He later bought vodka and a knife at a Lidl supermarket and went to Ludwell Valley Park, where he fatally attacked Mrs England and took her mobile phone.

After leaving the park, Davis went to shops and two pubs in Exeter before being spotted on CCTV sitting on the pavement in the city centre at 9.30pm.

He was arrested on suspicion of murder, telling police: “I f***** warned you c****, that’s why I f****** done it. I didn’t want to but none of you f****** c**** listened.”

Davis later said: “Why didn’t they listen to me at the hospital? The people at the hospital should pay for this. I cried out for help.”