Italy and UK attempt to play down the diplomatic row over the Nigerian hostage rescue attempt.
The radical Islamist group want Sharia Law in Nigeria and have killed scores in attacks on churches in the country's north.
A British building contractor and his Italian colleague taken hostage in Nigeria were killed before rescuers could reach them.
In a statement, the family of Chris McManus described the overwhelming feelings of trauma and pain when they were told of his death.
"We accept that the decisions reached and taken by the authorities were the only ones possible based on the information available.
"Two years ago we lost our beloved Chris, the trauma, pain, horror and distress have been overwhelming and intense. We are living our way through the grief with the tireless support and love of our family and friends. Our thanks and love goes out to each and every one of them.
"Chris cannot be hurt any more; we and all those who loved him will always remember the way he lived and not the way he died."
Recording a verdict of unlawful killing the Coroner said:
– Wiltshire and Swindon Coroner, David Ridley
Within the first minutes of the operation was when Chris was fatally shot. Those two insurgents who were seen leaving the compound, I'm satisifed that one of those was responsible for Chris's death and also Franco's. Chris died from the result of a devastating gunshot wound to the head.
The pathologist who carried out the post-mortem found that in addition to head wounds, Christopher McManus also suffered injuries to the left leg, the left arm and torso. One section of the report read:
Death would have followed rapidly if not immediately... There would have been nothing a medical responder, however promptly they had been on the scene, could have done to save his life.
A British hostage was killed by his captors as Special Forces were storming the building where he was being held, a coroner has concluded.
28-year-old Christopher McManus had been working as a Quantity Surveyor in northern Nigeria when he was taken hostage with an Italian colleague in May 2011. They were shot dead ten months later just minutes into a rescue attempt.
Coroner David Ridley, recording a verdict of unlawful killing, said he had 'no doubt' the hostages were killed by one of two insurgents seen fleeing the building.
The inquest heard Christopher suffered multiple bullet wounds consistent with an AK47 assault rifle.
British officials had worked for months trying to track down the captured men as rumours floated that they had been taken out of the country.
Nigerian government sources said that the men were killed before the arrival of security forces.
The wife of one of the guards holding the hostages in Nigeria claimed they were taken into a toilet and shot dead during the failed rescue attempt.
Today's hearing will take place at Wiltshire and Swindon Coroner's Court in Salisbury.
The failed rescue operation caused a diplomatic row between Britain and Italy after Italian president Giorgio Napolitano said it was "inexplicable" that Downing Street had not alerted Rome to the plan to rescue the men in advance.
But Foreign Secretary William Hague insisted it had been impossible to inform the Italian authorities in advance.
Mr McManus, 28, was working for the construction company B.Stabilini when he was kidnapped on May 12 by gunmen who stormed his apartment in the city of Birnin-Kebbi, about 110 miles away from Sokoto.
Mr Lamolinara was also abducted. A German colleague managed to escape by scaling a wall, but a Nigerian engineer was shot and wounded.
An inquest will resume today into the death of a British construction worker who was murdered in Nigeria by an Islamist sect before a failed commando rescue operation.
The attempt on March 8 last year by Nigerian troops and UK Special Boat Service commandos in Nigeria's north west city of Sokoto led to the death of Chris McManus from Oldham, Greater Manchester.His Italian colleague Franco Lamolinara also died.
The pair had been kidnapped in May 2011 and held for months before their execution.
The body of Italian hostage Franco Lamolinara will be repatriated to Rome later today (via @ansa_topnews).
The wife of one of the guards holding a Briton and an Italian hostage in Nigeria claims they were taken into a toilet and shot dead during a failed attempt to rescue them. Speaking to Reuters, the woman, who have her name as Hauwa, said:
There were about six men who came out of the house with the two hostages. They came into our wing of the compound, pushed the captives into the toilet and just shot them. I screamed.