A man accused of murdering Thames Valley Police officer PC Andrew Harper has had the charge against him dropped.
Jed Foster, 20, was arrested and charged with the murder of the 28-year-old in Berkshire last month.
PC Harper died of multiple injuries after being dragged under a van while responding to a reported burglary on August 15.
The court heard that there was no longer “a realistic prospect of conviction” and moved to end the case against Mr Foster during the hearing at the Old Bailey.
Prosecutor Jonathan Polnay said: "A full file of evidence has been received from the police and fully reviewed.
"The CPS has concluded that the full code test is not met and there is not a realistic prospect of conviction.
"Proceedings against Mr Foster cannot and should not be continued."
Mrs Justice Whipple informed Mr Foster that the prosecution had served a notice of discontinuance of their case against him.
"That means that you are no longer to be detained in custody," she said.
Three teenagers charged with the murder of PC Harper also appeared at the Old Bailey today.
Henry Long, 18, and two 17-year-old boys, who cannot be named, were remanded in custody and will reappear at the court on December 13.
They, along with Thomas King, 21, are also accused of conspiracy to steal a quad bike.
King was released on conditional bail to return to Old Bailey on December 13 as well.