Police officer Andrew Harper was dragged for more than a mile along a road and killed in “truly shocking circumstances”, a court has heard.
Prosecutor Brian Altman QC told the Old Bailey on Monday that the alleged murder of the 28-year-old constable was “a completely senseless killing”.
Pc Harper died from multiple injuries when he was pulled along behind a car after responding to the reported theft of a quad bike from a home near the village of Sulhamstead in Berkshire.
One witness mistakenly thought he had seen a bloodied deer attached to the car before realising it was a man being dragged along, the jury heard.
The court was shown dashcam footage of the trail of blood left on the country lane.
Henry Long, 18, from Mortimer, Reading, and two 17-year-olds, who cannot be named for legal reasons, all deny murdering the Thames Valley Police officer in August last year.
Mr Altman told jurors: “Late at night, on Thursday August 15 of last year, in Berkshire, 28-year-old Andrew Harper, a serving police constable of Thames Valley Police, was killed in truly shocking circumstances.
“With his ankles caught in a strap that was trailing behind a car being driven at speed along a country lane, he was dragged for over a mile along the road surface, 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.
“When, at last, he became disentangled, he was left with the most awful injuries, from which he died there on the road, surrounded by colleagues who tried in vain to save him.”
Mr Harper, left wearing only his socks and boots, suffered injuries that were unsurvivable, the court heard.
The jury was told: “This was a completely senseless killing of a young police officer in the line of duty.”
Long has admitted manslaughter, which the younger boys deny, and all three have pleaded guilty to conspiracy to steal a quad bike.
Pc Harper, known as “Harps” to his colleagues, was part of Thames Valley’s Roads Policing Unit, and had been due to work a 10am to 7pm shift that day.
He was still on duty with crew mate Pc Andrew Shaw at 11.17pm, and they were driving in an unmarked police BMW fitted with emergency lights.
The pair, who were both wearing uniform, answered the call to the reported theft of the quad bike although it was past the end of their shift.
Mr Altman said: “Despite it being well beyond the end of their shift, because they were close and thought they could help, they responded to the call. It was a decision that was to cost Andrew Harper his life.”
Prosecutors claim that the three defendants had planned the theft, visiting the home of owner Peter Wallis earlier that day and taking steps to avoid being caught by police.
It is alleged that having been challenged by Mr Wallis earlier in the day, they returned with items that could be used as weapons if they were challenged, including crowbars, an axe and a hammer.
Mr Altman said: “They were ready, as part of their planning, if necessary, to use the items they had brought with them as weapons if anyone stood in their way.
“Sensibly, Mr Wallis did not stand in their way this time.
“Pc Harper did try to stand in their way, and he paid the ultimate price for it.”
The court heard that the officers were driving along a country lane, Lambdens Hill, on their way to the call when they met a Seat Toledo, driven by Long, coming the other way.
One of the 17-year-olds was in the passenger seat, and the other was riding the quad bike which was being towed behind the car, attached to the boot lid hinge with a crane strap that formed a loop.
As the cars met, the teenager on the quad bike dismounted, disconnected the strap from the bike and tried unsuccessfully to get into the passenger door of the Seat, as Long began to drive off.
Pc Shaw turned the BMW’s emergency lights on, and the teenager ran to jump through the back passenger window of the Seat.
As Pc Harper tried to stop him, the officer’s feet were encircled in the crane strap, and he was dragged along as Long drove off.
The court heard that Long drove at an average speed of 42.5mph, leaving a snaking trail of tyre marks, blood and clothing as he swerved across the country lane.
A driver who had to slam on his brakes to avoid hitting the Seat as it crossed the A4 mistakenly thought Pc Harper was an injured deer.
Mr Altman said: “At first he thought there was a bloodied deer attached to the car, but quickly realised it was a person, trapped by both ankles, being dragged around the road and striking the kerb.”
Pc Harper was barely alive when he was found by his crew mate, and had suffered “absolutely catastrophic, unsurvivable injuries”, the court heard.
Several members of Pc Harper’s family were in court as the prosecution case opened.
Some were not present as dashcam footage of the trail of blood left on the road was shown to the jury.
A camera on the front of the police BMW captured the marks on the tarmac as Pc Shaw drove down country lanes looking for his crew mate.
The clip shown to the jury ended as Pc Shaw crossed over the A4 and met another officer who was tending to Pc Harper, seen lying bloodied in the road.
The case was adjourned until Wednesday.