The police marksman who shot Mark Duggan dead is due to give evidence to the inquest into the 29-year-old's death today.
Jurors have already been told that the officer, known only as V53, claims he opened fire on Mr Duggan in self defence because the father-of-four was brandishing a gun.
Mr Duggan was shot when the taxi in which he was travelling was stopped by armed police in Tottenham, north London in August 2011.
V53 has claimed that he had a gun in his hand as he got out of the car and was bringing it up to aim at officers.
Last month counsel to the inquest into Mr Duggan's death, Ashley Underwood QC, told jurors at the Royal Courts of Justice: "Mr Duggan wasn't shocked into submission, he got out of the minicab and he ran.
"You will hear from V53 that he was running with a gun in his hand and he started to bring the gun into the aim.''
The officer said he had opened fire "in self-defence'', and that the first shot failed to incapacitate Mr Duggan, so he fired a second time.
However the panel of eight women and three men also heard that the gun was found 10 to 20 feet away from the site of the shooting, and that Mr Duggan may have had a mobile phone in one hand just before he was killed.
They are being asked to address two questions - firstly whether the operation that ended in Mr Duggan's death was planned and implemented in a way that minimised to the greatest extent possible recourse to lethal force.
The second issue is whether it was absolutely necessary for the officer to fire two shots, one of which would have proved fatal "within 10 heartbeats''.
One shot hit him in the right biceps, and the other, fatal blow, hit the right side of his chest, hitting his aorta and exiting the left side of his back.
Claims were made in an anonymous letter sent last year to a number of people including Mr Duggan's family and the Comissioner of the Metropolitan Police that a police informant had told his handler that he could persuade Mr Duggan to pick up the gun, allowing officers to arrest him.
It was alleged that this operation would inevitably end in Mr Duggan being shot dead in order to avoid the informant being exposed.
The letter has been dismissed by Scotland Yard as false claims designed to discredit the officer who acted as handler to the informant.
On the day of the shooting, police were acting on intelligence that suggested Mr Duggan was on his way to pick up a gun from another man, Kevin Hutchinson-Foster.
He is serving a jail term for supplying the gun, but denied to inquest jurors that he had done so.