A second post-mortem examination is to be carried out on a prison officer after lawyers for a man accused of his murder questioned the cause of death, a court has heard.
Solicitors representing Christopher Alphonsos Robinson have also asked for a review of the medical care given to Adrian Ismay in the 11 days between him suffering serious leg injuries when a bomb exploded under his van, and having a fatal heart attack.
Mr Ismay, a 52-year-old father of three, died on Tuesday when a blood clot triggered cardiac failure.
He had been released from hospital in the wake of the blast in east Belfast on 4 March and had reportedly been making good progress.
A dissident republican group calling itself the New IRA claimed to have carried out the attack.
Mr Robinson, 45, had originally been charged with attempted murder prior to Mr Ismay's death.
That charge was changed to murder on the basis of a post-mortem report. He is also facing a charge of possession of an explosive with the intention to endanger life.
He appeared at Belfast Magistrates' Court today to face the substituted charge.
A police detective, who told the district judge he could connect Mr Robinson with the charge, outlined the preliminary post-mortem findings to the court.
"Mr Ismay died from pulmonary embolism due to deep vein thrombosis following explosion injuries to the legs," he said.
Mr Robinson's solicitor, Padraig O Muirigh, asked the officer if the cause of death could be described as a clot.
"That would be correct," he replied.
Mr O Muirigh told Judge Austin Kennedy that his request for a second post-mortem examination has been approved by the coroner.
He said it would be performed by Glasgow University pathologist Dr Marjorie Turner either later today or on Monday.
The solicitor said he also wanted a review of Mr Ismay's care both in hospital and as an outpatient.
"There are issues in regard to causation," he said.
The first post-mortem examination was carried out by Professor Jack Crane, Northern Ireland's former state pathologist.
Mr Robinson, from Aspen Park in Dunmurry, was remanded back into custody.
He will appear in court again, via video-link from prison, on 1 April.