Three teenagers are due to go on trial over the death of Pc Andrew Harper.
The Thames Valley Police officer died from multiple injuries after being dragged under a vehicle while on duty on August 15 last year.
The 28-year-old newly-wed had been responding to a suspected burglary when the incident took place near the village of Sulhamstead in West Berkshire.
Henry Long, 18, from Mortimer, Reading, and two 17-year-old boys, who cannot be named for legal reasons, are all charged with murder, manslaughter and conspiracy to steal a quad bike.
Long has denied murder but admitted manslaughter and conspiracy to steal a quad bike.
One of the 17-year-olds has denied all the charges while the third has, to date, entered not guilty pleas to manslaughter and conspiracy to steal.
Thomas King, 21, from Basingstoke, has pleaded guilty to plotting to steal a quad bike before Harper’s death.
The case, at the Old Bailey, is expected to last for up to six weeks.
