Three teenagers have been convicted of killing Pc Andrew Harper as they evaded arrest.
All three were standing trial for murder, but the jury found them guilty of the lesser charge of manslaughter.
Driver Henry Long, 19, who dragged Pc Andrew Harper to his death, was found not guilty at the Old Bailey of murder, but had previously pleaded guilty to manslaughter.
His passengers Jessie Cole and Albert Bowers, both 18, were also cleared of murder but found guilty of manslaughter.
Newlywed Pc Harper, 28, became entangled in a tow rope attached to their Seat Toledo as he tried to apprehend them.
Long drove off at “breakneck” speed, dragging the Thames Valley Police officer for more than a mile along country lanes before he was dislodged, having suffered horrific injuries.
The teenagers admitted plotting the theft and Long pleaded guilty to manslaughter but each denied knowing that Pc Harper was there.
Their defence claimed the incident was a “freak event” that none of them could have planned or foreseen.
But the prosecution said at more than 6ft and weighing 14 stone, the defendants must have been aware Pc Harper was being dragged to his death.
A reconstruction suggested that rather than stopping, Long swerved in the road to try to throw him off.
Jurors also saw dashcam footage that appeared to catch the moment Cole turned towards the officer before diving through the window of the getaway car and making good his escape.
Pc Harper’s tearful widow Lissie was comforted by other family members in court as the verdicts were delivered.
Mr Justice Edis adjourned sentence until next Friday.
It can now be reported that 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.”
Jury protected amid fears of intimidation campaign
The Pc Andrew Harper case was dogged by alleged attempts to “frustrate” the investigation and fears over jury nobbling, it can now be reported.
Detectives quickly tracked down the car which dragged Pc Harper to his death in Berkshire to the Four Houses Corner travellers’ site.
But the investigation was hampered by family and friends of the occupants, who were all said to have close ties to the site.
Thames Valley Police Detective Superintendent Stuart Blaik said: “A decision was taken very early on to arrest all the males on the site that night.
“While we were frustrated by family and friends, we have been able to work through that and establish exactly what happened and who was involved.”
Supporters of the teenagers – Henry Long, 19, Albert Bowers and Jessie Cole, both 18 – had crowded into the public gallery of the Old Bailey as the case got under way in March.
But no sooner had it started, Mr Justice Edis brought the trial to a halt over an alleged potential plot to intimidate jurors.
An unidentified person in the public gallery overlooking the courtroom was seen pointing at jurors.
Defence barrister Timothy Raggatt QC dismissed the incident as “a touch oversensitive”.
In the absence of the jury, he said: “In the circumstances, someone could be pointing for all sorts of reasons. Take, for example, there appear to be a lot of ladies in this court.”
But Mr Justice Edis ordered extra security measures to protect the jury.
Without divulging details, he said police had received information “that an attempt is being considered by associates of the defendants to intimidate the jury”.
The jury was provided with a private room, and anyone entering the public gallery was asked to provide proof of their identity.
A third measure was kept secret.
On the day the nation went into lockdown, the original jury was discharged.
When the case returned for retrial in June, social distancing in court was introduced to combat the risk of Covid-19 and security was further stepped up.
Jurors were referred to by number rather than their name to be sworn in.
And uniformed police were out in force during a jury visit to rural Berkshire.
Officers lined the narrow country roads as the jury viewed the spot where Pc Harper was killed.
A police drone buzzed overhead as detectives jump-started the defendants’ battered old Seat Toledo as the jury moved on.
With the end of the retrial in sight, fears for its integrity surfaced on July 20.
An overly friendly juror was seen by a prison officer to mouth “Bye boys” to the defendants in the dock.
On being alerted to the incident, Mr Justice Edis said: “She must have been compelled by some strong motive to have behaved as she did in this court under the observation of so many.
“It was both overt and covert at the time, which is remarkable behaviour.”
The female juror was discharged just a day before the remaining 11 men and women began deliberating on their verdicts.