Mark Duggan died "within 10 heartbeats" of a bullet fired by a police marksman striking his aorta, after intelligence was received that he had collected a gun and was part of a gang, an inquest jury has heard. The jury was told police believed Duggan was a member of TMD, Tottenham Man Dem, which officers believed had links to guns used in nightclubs.

The shooting of Duggan, 29, in north London on 4 August 2011 after armed police forced a cab he was travelling in to stop, triggered the worst riots in modern English history.

On Tuesday Ashley Underwood QC, counsel to the inquest, outlined the facts and issues in the case to the inquest jury, warning them that the evidence was complex and contradictory: "An awful lot of the evidence is going to point in all sorts of different directions."

The jury heard that the officer who shot Duggan twice, known as V53, would say he had seen a gun in Duggan's right hand, and believed the suspect was preparing to use it. They were told that V53 would testify that he had acted in self-defence, fearing that his own life or the lives of his colleagues were in danger from Duggan.

The jury was told that the key issue was whether Duggan was holding a gun, as the marksman said, when he exited the cab and came face to face with armed police.

There was laughter from some in court when Underwood said that V53 and a second officer, W70, would testify they had both seen Duggan holding a gun but were surprised when they later did not find it.

In fact, the gun, wrapped in a sock, was found on the other side of a fence 10 to 20 feet away from where the fatally injured Duggan fell to the pavement, the jury heard.

The gun, which was capable of being fired, had no DNA from Duggan on it. Gun residue was also absent from the deceased, save for a speck in his back pocket which the jury was told was scientifically irrelevant. His fingerprints were on a shoebox found inside the cab in which it is believed the gun had been stored, and traces of the drug ecstasy were in his bloodstream.

Underwood also said the jury would be asked whether Duggan could have been holding a mobile phone when he left the cab. Seconds before the cab was made to halt, Duggan had held a three-minute conversation with his brother Marlon.

The opening by Underwood was the most detailed public account yet of the police shooting which led to the riots in summer 2011 that erupted across London and then spread through the country.

In the days before the shooting, the Metropolitan police had received intelligence from the Serious Organised Crime Agency about the gang, of which Duggan is alleged to have been a member.

It ran a four day operation codenamed DIBRI targeting six members of the gang TMD, one of whom was Duggan.

That intelligence led to Duggan being placed under surveillance, as officers were said to have feared he would try to get a gun from a man called Kevin Hutchinson-Foster, who was later convicted at a criminal trial of supplying Duggan with the gun.

On his last night alive Duggan attended a family barbecue, and in court his relatives heard details of his death outlined.

Intelligence was still developing as Duggan travelled in a cab to east London, where police suspected he was planning to collect the gun.

Firearms officers deployed to stop Duggan were then told he had already picked up the gun. The police then used a "hard stop" – boxing in the taxi and forcing it to come to an abrupt halt – a "shock and awe" tactic designed to stun the occupants into submission and compliance, said Underwood.

But it did not work, Underwood said: "Mr Duggan wasn't shocked into submission. He got out of the minicab and he ran. You will also hear, of course, from V53 that he was running with a gun in his hand and he started to bring that gun up into the aim."

Two shots were fired rapidly by the marksman. The first shot struck Duggan in one of his biceps. The second, entering through the chest and exiting his back, killed the father of four. Underwood said: "The chest wound would have been fatal within about 10 heart beats, you will be hearing, but it would not necessarily have stopped somebody moving then and there."

Underwood said key issues would be whether it had been "absolutely necessary" for V53 to open fire, and whether planning by police chiefs had minimised the likelihood that lethal force would have to be used.

The inquest will sit next on Thursday, when the jury of eleven will visit the scene in Leyton, east London, where Duggan is alleged to have collected the gun, and the spot in Ferry Lane, Tottenham, where he died.