This afternoon judge Mr Justice Wilkie told them they must do so “coolly and dispassionately” and not allow “emotions, pre-conceptions or prejudice” to sway them.
He said: “You and you alone are judges of facts. Do not speculate on other evidence there might have been but has not been called.”
Mr Justice Wilkie had spent the afternoon summing up the evidence heard since the trial began on November 14.
He will continue his summing up tomorrow when he will deal with forensic evidence in relation to the firearm and dagger as well as medical evidence.
The jury is likely to retire to consider its verdicy at around 11am.
Bringing the prosecution case to a close earlier today, Richard Whittam, QC, said: “The sheer brutality of her murder and the utter cowardice of her murderer bring the two extremities of humanity face to face.”
He went on to detail the initial attack on the Batley and Spen MP by defendant Thomas Mair.
He said: “Most likely Jo Cox was shot once in the head followed by a brutal attack with a dagger.
“Despite the element of surprise and the inequality of arms he failed. Perhaps he underestimated the courage and tenacity of Jo Cox.”
The court had previously heard how Mair then made a second assault on the MP, stabbing her repeatedly and shooting her twice more.
Jurors were reminded of evidence from witnesses and the attempted intervention by Bernard Carter-Kenny, who was stabbed once in the chest.
After recapping the case, Mr Whittam said: “The overall affect of the evidence is compelling and establishes Thomas Mair as her murderer and the man who inflicted serious injury on Bernard Kenny.”
Earlier, the court had been told that no defence case would be presented and Mair would not be taking the stand.
Mr Whittam said: “Thomas Mair has not given evidence. He is perfectly entitled to sit back and say nothing.
“But in the context of this case the weight of evidence is obvious. In not giving evidence there is nothing to contradict or explain the evidence you have heard.
”You may think that it is quite clear that he did not give evidence because he has nothing to answer to the prosecution’s case. Had he given evidence it would have failed to defy any scrutiny by me in front of you.”
Defence barrister Simon Russell-Flint, QC, told jurors they had a duty to only convict his client of any of the charges if they were certain that the prosecution had proved the case against him to the highest of standards.
He said what had happened to Mrs Cox and Mr Kenny was “truly shocking and appalling”.
He added: “Mrs Cox’s death has touched many hundreds, perhaps thousands, of people.”
Evidence was given earlier by Detective Constable Jamie Smith, who was the exhibits officer in the case.
He said he was satisfied that all items were kept secure at all times.
Among those items were various pieces of evidence gathered at the home of defendant Thomas Mair.
Yesterday jurors at the Old Bailey heard he allegedly collected a dossier on Batley and Spen Mrs Cox.
A file found at his home in Lowood Lane, Birstall, included stories about her from newspapers.
There was a copy of a Batley News column which Mrs Cox had written about why she was in favour of remaining within the European Union.
Police officers made the discovery along with items relating to far right and white supremacy organisations, including a gold Third Reich Eagle ornament with a swastika on it on his bookcase.
The court has also heard this morning from Detective Sergeant Andrew Cass, the officer with day-to-day responsibility for the management of the investigation.
The officer said he was present at Westminster Magistrates on June 18 this year when Mairs made his first court appeareance.
He said that the defendant said: “Death to traitors, freedom for Britain.”
The court has previously heard eye witness accounts of the attack on Mrs Cox, which took place outside Birstall Library.
She was stabbed 15 times and shot three times during the assault by Mair, who was said to be armed with an adapted .22 hunting rifle and a ‘fighting dagger’.
CCTV footage showed him apparently waiting in the centre of the village for the MP to arrive at the library, where she was due to hold a surgery for constituents.
Mair, 53, of Lowood Lane, Birstall, is accused of murdering Mrs Cox, 41, in Market Street on the afternoon of June 16.
He also faces charges of possession of a firearm with intent to commit murder, possession of an offensive weapon – a dagger – and causing grievous bodily harm with intent to Bernard Carter Kenny.
Mair denies all four charges.
The trial continues.