The Police Service of Northern Ireland announced Wednesday that a post-mortem examination revealed 52-year-old Adrian Ismay "died as a direct result of the injuries sustained" after an explosive device placed under his vehicle detonated on March 4.
"Today is yet another difficult day for the Ismay family, his friends and colleagues as they struggle to come to terms with the events of the past 12 days," said Richard Campbell, a senior Northern Ireland police investigator.
"We have spoken to the family this morning and advised them of this development," he added. "We are also liaising with the Public Prosecution Service in relation to the individual who is currently charged with attempted murder and causing an explosion with intent to endanger life."
That suspect, Christopher Alphonsos Robinson, appeared Saturday in a Northern Ireland court
in connection with the bombing. He did not reply, but instead gave a loud sigh, when a court clerk asked him if he understood the charges against him.
It was not immediately clear what his reaction is now that he could soon be facing a charge of murder, rather than attempted murder.
Robinson's lawyer told the court this weekend that in 16 police interviews, Robinson was not shown any evidence linking him to the attack. But a detective said, also in court, that police can link the 45-year-old from Dunmurry, on Belfast's outskirts, to the crime.
Fears of more dissident attacks
Campbell asked Wednesday for the public's help in tracking down two vehicles believed to be involved in the March 4 bombing in Northern Ireland's capital.
The British territory's police service initially indicated that Ismay, the only person wounded in the blast, had suffered severe but not life-threatening injuries.
"Adrian Ismay gave over 28 years of service to prisons in Northern Ireland and he was greatly respected by all those who knew him," Justice Minister David Ford and Northern Ireland Prison Service Director General Sue McAllister said in a joint statement.
Some expressed fears that the bombing could be the start of more carnage ahead of an Irish dissident uprising's milestone anniversary known as Easter Rising, which happened in Ireland in 1916.
That's when a small force of nationalists managed to briefly occupy parts of Dublin before being defeated by the then-controlling British forces. Yet the dissidents kept fighting, ultimately helping to secure Ireland's independence a few years later.
Northern Ireland still falls under the UK umbrella, though it has seen plenty of tension and violence.
Nearly 3,600 people died in a late 20th-century conflict known as "The Troubles," that pitted pro-British Protestants against Catholics who wanted to wrest Northern Ireland from British control and unify it with Ireland.
That violence largely ended with the historic Good Friday power-sharing agreement in 1998. Still, the opposition to British rule never went away entirely.
Following the March 4 Belfast bombing, Northern Ireland Assistant Chief Constable Stephen Martin said there was an "extremely high" threat of more dissident attacks in conjunction with the Easter Rising centenary. At least four events are being held to mark the uprising, the first on March 26.
Security forces have beefed up their presence in key locales, concerned that splinter groups from what was once the Irish Republican Army will target police, prison officers and soldiers, according to Martin.