British troops will not face charges over the deaths of a fellow soldier and a civilian in Iraq, the attorney general has said.
Sgt Roberts had given up his body armour, which could have saved him
Sgt Steven Roberts was shot dead when UK troops opened fire during a disturbance at a roadblock at Al Zubayr near Basra, on 24 March 2003.
Iraqi Zaher Zaher was shot and killed in the same incident.
Sgt Roberts, 33, from Shipley, West Yorkshire, had given up his body armour because of shortages.
A Metropolitan Police post-mortem examination found he had been hit twice but "may have survived" had he had body armour, BBC News has learned.
Attorney General Lord Goldsmith said there was insufficient evidence for charges.
The Metropolitan Police investigated both deaths after Lord Goldsmith removed the investigation from Army control.
Sgt Roberts, originally from Wadebridge in Cornwall, was a tank commander with the Second Royal Tank Regiment.
Legal sources say his family could now bring a civil case of negligence against the Ministry of Defence.
His widow, Samantha, said she "accepted" the decision not to bring charges but hoped for a full inquest into her husband's death, examining the evidence gathered by the Crown Prosecution Service (CPS).
Six soldiers had been waiting to hear whether they would face charges over the deaths.
Lord Goldsmith said the CPS believed it "now had the fullest account of what occurred, although the passage of time had undoubtedly adversely affected the quality of some of that evidence".
US soldiers were interviewed, as was an Iraqi witness and a post-mortem was carried out on Mr Zaher.
While there were differing versions of what happened, the CPS based its report on the "totality" of evidence.
Lord Goldsmith said: "The full investigation has established there is no realistic prospect of conviction."
The official account said that while Sgt Roberts was involved in a roadblock to stop and search vehicles for weapons, Mr Zaher approached, throwing stones at the tanks and then at Sgt Roberts, who was standing alone outside his tank.
Sgt Roberts pointed his pistol at Mr Zaher after he failed to stop when the British soldier held up his hand.
He fired, but the pistol malfunctioned, allowing Mr Zaher to advance, still throwing stones, according to the CPS report.
Warning shots from another soldier did not deter Mr Zaher, prompting soldiers from two tanks to fire "a number of shots at Mr Zaher".
"One of those weapons was set to fire at targets a considerable distance away and was not accurate at close range," Lord Goldsmith told the House of Lords.
"Although Mr Zaher was hit and severely injured in the arm, two of the bullets struck Sgt Roberts in the torso and he fell to the floor fatally wounded."
Soldiers went to help him, but one who feared the injured Mr Zaher would attack again fired several more shots at him.
Samantha Roberts wants a full inquest into her husband's death
He was fired at once more when he managed to get up off the ground and was thought to still pose a threat.
Both men were declared dead at the scene.
Sgt Roberts' widow Samantha, who said at the time that then Defence Secretary Geoff Hoon should resign over her husband's death, said the "full and detailed" investigation did not explain the death.
"I accept the decision taken by the prosecuting authorities and I accept that this decision is based on their careful scrutiny of the evidence," she said in a statement.
"The fact remains that three years after my husband's death, I know little more about how he came to meet his death than I did when I was first told that he had been killed.
"I can only hope that the coroner will now conduct an inquest into the circumstances of Steve's death, with full access to the evidence that has been gathered by the prosecuting authorities."