PC Andrew Harper’s mother has said she is ‘utterly and bitterly disgusted’ that his killers have been cleared of murder.
Debbie Adlam slammed the manslaughter convictions given to Henry Long, Albert Bowers and Jessie Cole.
She hit out at the ruling in a petition to ‘overturn a miscarriage of justice’, which has over 190,000 signatures so far.
PC Harper had tried to stop the three thieves from stealing a quad bike in Sulhamstead, Berkshire, in August last year.
The 28-year-old’s ankles were lassoed by a trailing loading strap from their car as the teenagers tried to escape.
He was towed helplessly for over a mile behind the Seat Toledo as it reached speeds of 60mph.
Long, 19, and 18-year-olds Bowers and Cole hugged as they were convicted of manslaughter via videolink from HMP Belmarsh in London on Friday.
Mrs Adlam said she was ‘utterly and bitterly disgusted with the outcome’, which she said had ‘let down’ PC Harper.
She wrote: ‘Andrew James Harper is my son. I am disgusted that he has been let down.
‘When they crossed the junction on A4 there’s no way they did not know he was there being thrown against the pavements.
‘Utterly and bitterly disgusted with the outcome. Andrew went to work to serve us all. And this is how he was repaid.’
Others agreed, with Suzanne Webb saying: ‘This is not justice. This is a joke.’ Peter Jones-Ward wrote: ‘How can deliberately dragging someone behind a vehicle not be murder?’
And Joseph Huitson added: ‘The lack of remorse shown and their callous attitude towards the grief stricken family. How can anyone cheer when someone has lost their life in such a way?’
PC Harper had married Lissie just four weeks before he was flayed alive by the surface of Admoor Lane and the obstacles at the side of it.
Parts of his body including his face were destroyed and the details of the opening of the trial were so terrible his family asked the media not to report them.
When the body was discovered by his colleagues after he had fallen away from the sling he was completely naked except for his socks.
A snaking trail of blood behind him marked the course his body had taken down the lane.
Lissie was joined in court by his parents Phil Harper and Mrs Adlam and his brother Sean.
Long admitted manslaughter but was acquitted of murder. Bowers and Cole were convicted of manslaughter after the jury deliberated for 12 hours and 22 minutes.
The verdict left Lissie ‘immensely disappointed’ and sparked fury from his friends and colleagues.
Family friend Andy Ledbury, who employed PC Harper at a roofing business when he was 18, said: ‘To say I’m shocked and disappointed would be a huge understatement.’
He further said the trio ‘knew exactly what they were doing’ as they dragged the constable to his death.
Mr Ledbury told BBC Radio Four’s Today Programme: ‘For me it was never a question of whether it would be murder or manslaughter it was a question of how many of them would be prosecuted for murder.
‘The more evidence you hear, the more it’s clear they knew exactly what they were doing and they were just preoccupied with their escape at all costs.’
Despite the verdict, he made clear his view that: ‘This was murder and will not in any way take away the pain of what’s happened, it’s about justice and for those that committed the crime.
‘As it stands at the moment it’s not showing much in the way of support for our police force which need it now more than ever.’
Jurors who were visibly shocked by the details of the case had been offered counselling before the trial began.
All the police officers involved in the discovery of his body were also advised to seek help to deal with the trauma of the case.
When he was arrested at the Four Houses Corner travellers site in Ufton Nervet, Berkshire, Long claimed he had been watching a Fast and Furious DVD at the time of the killing.
He complained police were unfairly targeting travellers and said: ‘I don’t give a f*** about any of this,’ when he was charged.
Long, Bowers and Cole, spent most of their time chasing rabbits and hares with their lurcher dogs and scratched a living by burglary and theft.
They had spotted the Honda TRX500 quad bike at the home of Peter Wallis, near Cock Lane, in the village of Bradfield Southend, earlier on August 15 and returned at around 11pm to steal it.
All of them were wearing balaclavas and gloves and they had taped over the car’s number plate and disabled the rear lights.
The killers were armed with an axe, crowbars and a length of pipe to use against anyone who tried to stop them.
Mr Wallis called the police saw them taking the bike and hitching the handlebars to the back of the car with the sling.
Long drove off with Bowers in the passenger seat and Cole riding the bike.
PC Harper was in an unmarked BMW with PC Andrew Shaw and was due to finish his shift at 7pm.
The officers were on duty that night in the Reading area and were heading back to their base station at Abingdon when they heard of the incident on the radio and responded to the call. It was a decision that was to cost PC Harper his life.
When they drove down Admoor Lane they came nose to nose with the Seat going the other way.
The travellers quickly realised it was a police car and Cole unhitched the bike and tried to get to the Seat as it rounded the police car to drive away.
PC Harper jumped out to try and stop Cole getting into the car but he managed to dive in through the passenger side window.
As the car sped away dragging the sling, PC Harper’s feet became entangled. Mercifully, he was likely to have been rendered unconscious almost immediately.
PC Shaw had no idea what had happened to his colleague and expected to find him further up the road. But as he reversed up the lane he found PC Harper’s shredded and bloodied stab vest lying in the road.
The court was told Long must have known he was dragging the officer and with the music blaring and his friends screaming at him, it was said he tried to free PC Harper by zig zagging along the lane.
By the time the officer fell away from the car at the end of Ufton Lane his body was a ‘bloodied mess’.
A police officer who saw the incident thought PC Harper’s body was a deer carcass.
The Seat sped away to the travellers site causing other road users to drive into the verge to avoid a collision.
It was tracked by a police helicopter and the travellers were arrested at the site.
Long, Bowers and Cole all admitted conspiracy to steal a quad bike and Long admitted manslaughter.
They insisted they had no idea that PC Harper was trapped behind the car but a macabre re-enactment of the incident with a mannequin showed they must have known the officer was being dragged to his death.
During the trial Long, Bowers and Cole smirked and laughed as details of PC Harper’s horrific death were read to the jury.
It can now be reported Long had previously threatened to ‘ram’ a police officer as he chatted with a police community support officer (PCSO).
In the conversation in July 2018, ruled inadmissible during the trial, Long said: ‘You can’t touch me now ‘cos I’ve passed my driving test and if police try to stop me I will ram them.’
Long and Bowers, both of Mortimer, Reading, and Cole, of Bramley, Hampshire, each denied murder and were acquitted.
They will be sentenced next Friday. Thomas King, 21, of Bramley, earlier admitted conspiring to steal the quad bike.