A police officer died when he was dragged for more than a mile by a car along a country lane, a court heard.
Andrew Harper, 28, got caught in a strap trailing behind a car in Berkshire on 15 August last year.
His uniform was “literally ripped and stripped from his body”, and he was “swung from side to side like a pendulum”, the Old Bailey heard.
Henry Long, 18, of Mortimer, Reading, and two 17-year-old boys deny murdering PC Harper.
Brian Altman QC, prosecuting, said Mr Long was driving, and the two youths, who cannot be named because of legal reasons, were passengers.
The jury was told PC Harper and a colleague were responding to a report of a quad bike theft near Sulhamstead.
Mr Altman said after the police officer became disentangled from the strap he was “left with the most awful injuries”.
He said he was “swung from side to side like a pendulum in an effort to dislodge him, losing items of his police uniform along the way, with the rest of his uniform being quite literally ripped and stripped from his body.
“He died totally naked apart from his socks and boots and some shredded remnants of the trousers he was wearing.”
The court heard Peter Wallis, who lived in Bradfield Southend, called the police at 23:17 GMT after seeing masked men “make off” with his new Honda TRX500 quad bike.
Mr Altman said PC Harper and PC Andrew Shaw responded to the call as they were driving along the M4, “despite it being well beyond the end of their shift”.
“It was a decision that was to cost Andrew Harper his life,” he added.
After coming off the motorway, the police constables entered Lamdens Hill, a “rural, unclassified single carriageway road”, where they “chanced upon” a Seat Toledo.
Mr Altman said Mr Long and one of the defendants were inside, and the third defendant was riding the quad bike as it freewheeled.
The bike had been attached to the hinge of the car’s boot by a “crane strap” wound around the bike’s handlebars.
‘Lassoed around ankles’
Mr Altman said after the unmarked police car and the Seat met on Admoor Lane, the defendant on the quad bike dismounted, unhitched the bike, and tried but failed to get inside the Seat.
The court heard the he “bolted” along the driver’s side of the police BMW towards the Seat which had “rounded the police car, so that the cars were now boot to boot”.
Mr Altman said “almost simultaneously” PC Harper got out of the police vehicle and began to run behind it to intercept him.
He added: “In his rush to ensure that he and his friends did not get caught, the defendant, who had unhitched the crane strap…. had been unable to replace the crane strap in the car boot.”
The court heard PC Harper did not realise where the strap was and stepped with both feet “into the loop made on the road surface”.
Mr Altman said as Mr Long “floored” the Seat to escape, PC Harper was “lassoed around his ankles by the loop of the strap”.
Mr Altman said: “It is the prosecution case that Long drove that car knowing full well that PC Harper was entangled in the strap, and he drove it in a manner calculated to dislodge him, and make good their escape, as had been their plan all along.”
PC Harper was barely alive when he was found by his colleague, and had suffered “absolutely catastrophic, unsurvivable injuries”, he said.
Mr Altman asked: “If Long and his friends had no idea that Andrew was entangled in the strap, why was there a need to drive so recklessly?
“The answer is easy to see. All three knew it was a police car that had confronted them.”
‘Screaming and shouting’
He said the idea that the defendant on the bike, “did not immediately tell Long and the other defendant that a policeman had come from the police car and had got within feet of him… is ludicrous”.
“The same goes for the idea that they did not know that the policeman had become entangled in the strap and was being dragged down a county lane,” he added.
“It’s not difficult to imagine the screaming and shouting that must have taken place inside that car about what was unfolding.”
Long drove at an average speed of 42.5mph, the jury was told, and left a “snaking trail” of tyre marks, blood and clothing as he swerved across the lane.
As the Seat crossed the A4 with PC Harper still “shackled behind” it another driver who slammed on his brakes thought there was a “bloodied deer attached to the car”.
Mr Altman said the three defendants were arrested later the same night at a traveller caravan site.
Mr Long has previously admitted manslaughter and conspiracy to steal a quad bike.
On Monday, the two 17-year-olds pleaded guilty to conspiracy to steal a quad bike. The pair also deny manslaughter.
The case before Mr Justice Edis is expected to continue for up to six weeks.