Two teenagers have appeared at the Old Bailey today for a pre-trial preliminary hearing in connection with the death of PC Andrew Harper in Berkshire last year.
18-year-old Henry Long, of Mortimer, Reading, appeared alongside alongside a 17-year-old boy from Reading.
He pleaded guilty to one count of manslaughter and one count of conspiracy to steal a quadbike, but denied murder.
The 17-year-old boy, who cannot be named for legal reasons, pleaded not guilty to one count of conspiracy to steal a quadbike.
On March 9 this year, they will stand trial alongside another 17-year-old boy.
All are charged with murder in relation to newly-wed PC Harper's death in Sulhamstead last August.