Aria died from a single stab wound to the chest at her home in Weston-super-Mare, north Somerset, on 15 December last year.
The 16-year-old boy, who cannot be identified due to his age, denied charges of murder and manslaughter in relation to Aria's death.
Giving evidence at Bristol Crown Court, the boy said he stabbed her accidently when he picked up a knife from the kitchen of Aria's home and went into the lounge where she was sitting on the sofa.
The boy later told the jury that he had taken the knife into show it to Aria to "scare" her.
He demonstrated moving the knife in a ninja-style way before jabbing it towards Aria as if he was fencing.
He said the knife accidentally went into Aria, causing the fatal injury.
Police and paramedics attended, but Aria was pronounced dead at 6.58pm.
After the verdict was read out on Thursday, several members of the public gallery - including Aria's mother Tori Hull - left the court room quietly.
The court had earlier been warned by judge Mrs Justice O'Farrell not to show any emotion when the verdicts were delivered.
"Members of the jury, I want to express my thanks to you for the work that you have done in this case - your careful attention to all of the evidence and the speeches as part of your civic duty," Justice O'Farrell said.
"I appreciate that this has been a distressing case.
"I am grateful to you for undertaking this difficult task with fortitude and calm reflection."
After the jury left the courtroom, Justice O'Farrell told the teenager: "You have been found not guilty and you will now be taken down to be processed."
Following the verdict, Avon and Somerset Police Detective Inspector Neil Meade said: "Aria Thorpe was a fun-loving girl, adored by her parents and wider family. She clearly brought a huge amount of joy to many people's lives.
"Aria's grieving family have shown exceptional courage over the past six months, particularly during this trial, and our thoughts are with them."
'I felt horrible'
During the trial, the boy described how he had picked up the 21cm blade and walked into the lounge.
He told the jury: "Aria stood up and I was waving around the knife.
"Then at some point I decided that I was going to try to make her flinch and scare her, to get a reaction.
"I leaned forward, acted like I was fencing."
The defendant said Aria had been in front of him at the time.
"She had almost taken a step forward but without taking a step forward because before she could, it happened," he said.
"I don't know what she was doing.
"The knife went into her. Then I pulled it out. I didn't know what to do. She put her hand to her chest."
The boy said Aria then fell to the floor.
The teenager then walked to Worle railway station, where he told a group of children that he had killed Aria accidentally.
He borrowed a phone belonging to another boy and searched "what happens if you kill…".
Another girl then called the police, prompting the boy to run onto a train, before he was arrested by officers.
When asked how he was feeling about what happened at that time, the boy replied: "I felt horrible".
Aria attended school and a dance class on the day of her death, before she and her mother made pizzas at home.
Ms Hull then left for an evening shift.
A family friend found Aria on the floor at about 6pm and rang police.
Three critical and six major shortfalls were highlighted in a report by the Human Tissue Authority (HTA) on Queen's Medical Centre, run by the Nottingham University Hospitals (NUH) NHS Trust.
It comes after a major inquiry found hundreds of mothers and babies died or suffered potentially avoidable harm because of "deeply embedded systemic failures" at the hospital trust.
Chair Donna Ockenden highlighted that leaders at NUH NHS Trust knew there were serious issues in the maternity department - but failed to take action.
Experts concluded there were "potentially avoidable" outcomes relating to 444 maternity cases examined up to May 2025, alongside 76 newborn cases.
Problems first came to light after Jack and Sarah Hawkins, whose daughter Harriet was stillborn in 2016, found out her body had been allowed to decompose so badly that it needed to be triple-bagged for her funeral.
Critical shortfalls highlighted
During the HTA body audit, the inspection team, who visited the trust in March, identified eight bodies that were showing "advanced deterioration due to not being transferred to a freezer within a sufficient timeframe".
The report said: "Due to the lack of freezers, it has become routine practice to use hermetically sealed bags, or body bags, to store the deteriorating deceased within a refrigerated 'isolation' area."
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The inspection team noted that this had a "detrimental effect on the condition and dignity" of the deceased.
They also pointed out that a lack of checks on wristbands in the mortuary was increasing the risk of the "wrong body being released to funeral services".
Another critical shortfall highlighted in the report was that "no systematic checks were being undertaken for certain categories of bodies".
The report added: "Bodies held in frozen storage, those contained within hermetically sealed bags, and those received in an advanced state of deterioration were not subject to ongoing condition checks."
A critical shortfall was defined in the report as being one which "poses a significant risk to human safety and/or dignity or is a breach of the HT Act or associated Directions" or is a "combination of several major shortfalls".
NHS trust responds to findings
Responding to the findings, Tracy Pilcher, chief nurse at NUH NHS Trust, said: "We recognise that some of the systems and processes used in our mortuary did not meet the standards expected by the Human Tissue Authority (HTA), our trust or of our patients, for which we are truly sorry.
"We take the concerns raised by the HTA very seriously and have already taken action to make improvements. We are grateful for the feedback from the HTA following the inspection and have met them to talk through their concerns and how we can improve."
She added: "While we have met the majority of the HTA standards, we know that there are some very important areas we need to change to ensure our patients and families have confidence that we care for their deceased loved ones in a manner which is dignified and respectful.
"Our teams have been working hard to take immediate actions, including transfer of paediatric post-mortems to our central post-mortem space as soon as it was highlighted by the HTA, increasing mortuary capacity, increasing condition checks, audit oversight and regularity, and further staff training and oversight for incident reporting. In addition, we have increased oversight of our services, to ensure that our practices are in line with standards and with an agreed route to board level reporting.
"We have also increased governance in this area, with further senior oversight and escalation to ensure continuous monitoring, timely escalation of risks, and assurance of sustained compliance."
Reaction to Ockenden report
James Murray, the health secretary, promised the government will present a national action plan to improve maternity care informed by Ms Ockenden's report by the end of the year.
The chief executive and chairman of the NUH NHS Trust have also reacted to the report's findings.
The independent review marks "a watershed moment for affected families, our staff and for the communities we serve", CEO of the trust Anthony May and chair of the board, Nick Carver, wrote in what they call "an open letter to the people and communities of Nottinghamshire".
"We apologise unreservedly to the women and families who have suffered harm, loss, trauma or distress while receiving care in our services," they added.
"We failed you, and on behalf of Nottingham University Hospitals Trust, we accept responsibility for our failings."
In May, the 74-year-old's third trial over the allegation ended in a mistrial after the jury said it was deadlocked.
The majority-male jury was unable to reach a unanimous decision over whether Weinstein had raped former aspiring actor Ms Mann, now aged 40, in 2013 in a New York hotel.
Ms Mann appeared to support the dismissal of the case, saying in a letter that a prosecutor read to the court: "After a lot of thought and reflection, I have chosen not to proceed with a fourth trial against Harvey Weinstein. It was clear to me at this last trial I could no longer endure going through this any longer."
Weinstein had a neutral expression as court officers led him out of court in his wheelchair.
He had pleaded not guilty to the charge of rape in the third degree, and has denied all allegations of nonconsensual sex.
The May mistrial came nearly a year after another New York jury failed to reach a verdict on a charge tied to Ms Mann's allegations, which she recounted across five days in court.
At his first trial in New York in 2020, Weinstein was convicted of raping Ms Mann and assaulting onetime production assistant Miriam Haley in 2006.
But the state's highest court overturned the conviction and Weinstein's 23-year prison sentence after concluding he did not get a fair trial.
A Manhattan jury then convicted Weinstein of sexually abusing Ms Haley at a trial in June 2025, but found him not guilty of assaulting former model Kaja Sokola.
The same jury were deadlocked on the third-degree rape charge relating to Ms Mann, and a mistrial was declared, paving the way for May's retrial.
Weinstein was convicted of rape in California in 2022 and is serving a 16-year prison sentence. He is appealing that conviction and sentence.
The Miramax studio co-founder will face up to 25 years in prison when he is sentenced for abusing Ms Haley.
Weinstein had remained in custody at New York's maximum-security prison, Rikers Island, serving a 16-year sentence for a separate Los Angeles conviction of rape and other sexual assault charges, while prosecutors weighed the possibility of a further New York retrial.
Speaking on the Electoral Dysfunction podcast, the veteran Labour peer said the "strongest candidates" were Mr Miliband and current Foreign Secretary Yvette Cooper.
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Asked to choose who it "should" be between those two, she said: "I'm caught between Ed and Yvette, but I think, marginally, Ed."
Mr Burnham, widely expected to replace Sir Keir Starmer as prime minister, is also thought to be planning to replace Rachel Reeves as chancellor.
Names rumoured to replace Ms Reeves, alongside Mr Miliband, include former health secretary Wes Streeting and Home Secretary Shabana Mahmood. Ms Mahmood is thought to want to stay in here current job, however.
On how to pick a chancellor, Baroness Harman said a prime minister needs to pick "somebody who's on the same page" as them.
She said: "You cannot have economic policy division and strife between No 10 and No 11."
Baroness Harman also said Burnham will "want a chancellor who is going to be radical".
"It can't be business as usual," said Baroness Harman. "The Treasury likes to be the deficit reduction department - it needs to be the growth generating department."
But, the former Labour deputy leader added that as well as someone "radical", the next chancellor also needs to be "credible".
She said that Mr Miliband is "radical", but also "experienced", and "knows the Treasury inside and out". She pointed to the energy secretary's past role chairing the council of economic advisers for former chancellor Gordon Brown in the early 2000s.
To make himself a "credible" chancellor, he would need to do "something big to show that he understands the fiscal cliff edge we're on".
On Ms Cooper, Baroness Harman said although she "is not being talked about so much", she also has experience in the Treasury, and is also "radical".
The incident happened shortly before 8.50am on Thursday at the level crossing in Hoghton, Lancashire, British Transport Police (BTP) said.
BTP added that woman was pronounced dead at the scene, while the girl remains in "critical condition" in hospital. They were the only people in the car.
A BTP statement read: "Two people were in the car, and sadly a woman was pronounced dead the scene, an eight-year-old girl was taken to hospital where she remains in a critical condition.
"There have been no other injuries reported from passengers on the train."
The Rail Accident Investigation Branch are investigating the collision.
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BTP Superintendent Jamie McGowan said: "Today's events are truly devastating, and our thoughts are firmly with the family of the woman who sadly lost her life and the young girl in hospital with serious injuries.
"Members of their family are being supported by specially-trained officers.
"Detectives remain at the scene working closely with the Rail Accident Investigation Branch, and enquiries are ongoing to establish exactly what led to the collision."




