Jermaine Paul, 23, and Malique Thompson-Hill, 22, are accused of killing Khalid Abdi Farah, 26, who was gunned down outside a shop in Southall, west London, on November 11 last year.
Prosecutor Mukul Chawla QC told the jury at the Old Bailey in London on Wednesday, August 8, Mr. Farah's death was undoubtedly a "cold-blooded execution".
"What we don't know is why it happened. What made someone shoot him at point-blank range and then for good measure shoot him again? What was the motive? We don't know. But it was a cold-blooded execution and someone did it," Mr. Chawla told the court.
'Involved In Illegal Drugs'
Paul and Thompson-Hill have given evidence during the trial and both have admitted "being involved in illegal drugs" although they denied having anything to do with Mr. Farah's death.
A key plank of the prosecution evidence is data from a tracker device in Mr. Paul's Volkswagen Golf, which Mr. Chawla said fitted in with the prosecution's version of events.
But Paul's barrister, James Scobie QC, called an expert witness who said the telematic device, installed by his insurance company Insurethebox, was prone to error and full of "anomalies".
Testimony by Dr Chaz Dixon, an internationally recognized expert in position navigation and timing systems, was reputed by the prosecution's own expert witness, Professor David Last, a consultant engineer.
On Wednesday, August 8, Mr. Scobie read out a further statement by Dr. Dixon in which he rebutted Prof. Last's testimony.
Thirty 'Anomalies' In Tracker Data
Dr. Dixon said he had assessed the data from the tracker device in Mr. Paul's car over a six week period and found at least 30 "anomalies" which showed it was "misleading" and "not reliable".
"I find it inconceivable that any clock which is probably synchronized would exhibit such inconsistency," said Dr. Dixon, who said the device should have been independently tested to check whether or not it was accurate.
But Mr. Chawla read out another statement from Prof. Last in which he disputed Dr. Dixon's claim that the device was "malfunctioning".
He said the so-called anomalies were a "known phenomena" which Insurethebox were aware of and he insisted they did not undermine the tracker data itself, which suggested Mr. Paul returned to his home shortly before 1am.
"Where Dr. Dixon sees anomalies I see a vehicle in an urban area struggling to find a GPS signal….there is no reason to suggest the clock has malfunctioned and nor has Dr. Dixon identified any anomalies between midnight and 2.39am on November 11," said Prof. Last in his statement.
Identity Of Gunman Not Known
Mr. Chawla said the Crown could not prove who fired the fatal shots but they said there was conclusive evidence — mobile phone cellsite evidence, CCTV footage and the tracker data — which proved Paul and Thompson-Hill were the two men in a stolen VW Tiguan in Lady Margaret Road, Southall, at 1.23am on November 11.
One of them was driving and the passenger fired the fatal shots, said Mr. Chawla.
Mr. Chawla said a series of "midnight calls" made by Mr. Paul "give the lie" to his version of events and he said both defendants had "invented shadowy figures whose very existence cannot be established" in an effort to divert attention and blame away from themselves.
The getaway car was later found burnt out in a road in West Drayton, near Heathrow airport.
A third man, Joshua Folorunso, 27, is accused of attempting to pervert the course of justice by setting fire to the Tiguan, which had been stolen two weeks beforehand and was fitted with cloned number plates at the time of the killing.
The trial continues and the jury is expected to be sent out to deliberate on Friday, August 10.