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.
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.
Pc Andrew Harper's Funeral - In pictures
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.
