The jury in the murder trial of Pc Keith Blakelock has retired to consider its verdicts.
Nicky Jacobs, who was 16 at the time, is accused of being one of the rioters who repeatedly stabbed the officer and tried to decapitate him during disturbances in Tottenham, north London, on October 6 1985. He denies murder.
During his trial at the Old Bailey, the jury have heard from three anonymous witnesses who claim to have seen Jacobs taking part in the killing.
The 45-year-old is also alleged to have written a rap poem while serving time in a juvenile detention centre in which he boasted about "chopping" at the officer.
And the prosecution claims that in 2000 Jacobs told a police officer: "F*** off, I was one of them who killed Keith Blakelock."
But his defence team have questioned the credibility of the Crown's key witnesses, who have received payments from police.
And they claimed that the account Jacobs gave of the wounds Pc Blakelock received in the rap poem did not tally with the findings of the post-mortem examination.
Pc Blakelock, 40, was killed as he tried to protect firefighters tackling a blaze at the height of unrest on the Broadwater Farm estate.
Violence broke out there after local woman Cynthia Jarrett died of a heart attack as police searched her house.
Summing up the case, judge Mr Justice Nicol told the seven men and five women on the jury to set emotions to one side when reaching their verdicts.
"The killing of Pc Blakelock was a dreadful act, but that cannot help you decide whether the Crown has proved the defendant is guilty of his murder," he said.
"You may have sympathised with some witnesses or had different feelings towards others.
"I have already said you will have to make your own assessment of their credibility - whether you believe what they had to say - but that is not the same as basing your decision on whether you liked or disliked a witness.
"Do not let emotion influence you."
The jury was sent home and will resume its deliberations tomorrow morning at 10am.