An adopted Romanian orphan baby died after being starved of oxygen, a disciplinary hearing has been told.
Dr Michael Curtis is accused of serious professional misconduct
The General Medical Council is deciding whether an assistant state pathologist for Northern Ireland, Dr Michael Curtis, was at fault over baby David Briggs' post-mortem examination in October 2000.
Dr Curtis had twice said the cause of his death could not be ascertained.
However, expert witness Dr Jean Keeling told the hearing on Wednesday that damage to the baby's heart, brain and lungs was evidence of a lack of oxygen caused by interference with his breathing.
"We just can't write off this sort of evidence of damage," she said.
The paediatric pathologist also said rib fractures on his body, missed by Dr Curtis at the initial post mortem, were inflicted with "considerable force" either through squeezing by someone with big hands or by crushing against a hard surface.
She said the infant had previously been subjected to serious assaults on more than one occasion.
Dr Curtis began giving evidence on Wednesday afternoon, but the bulk of his testimony is expected to be heard on Thursday.
The GMC's Professional Conduct Committee hearing in Manchester follows a report into the death of the baby, who was legally adopted by County Armagh man Geoffrey Briggs and his wife.
Geoffrey Briggs no longer lives in Northern Ireland
The boy, who suffered multiple fractures, was buried without the injuries ever being explained.
It is understood the couple, who adopted the boy and his twin brother, have been questioned by police in connection with the death.
Former overseas missionary Briggs, from Portadown, was later jailed for fracturing the skull of the child's twin brother.
A 45-page Department of Heath report published in September last year, was highly critical of the Craigavon and Banbridge Community Trust, which oversaw the adoption.
One of the key findings said there was a failure to visit and support the children along with poor record-keeping.
Briggs adopted the nine-month-old twin boys under Romanian law in July 2000.
Less than four months later, one was dead and the other had a fractured skull.
The first child was pronounced dead at Craigavon Area Hospital in October 2000.
It is understood a post-mortem examination was carried out at the hospital at the time, but no death certificate was issued, and the body was buried.
Just 13 days after that, the boy's twin was admitted to the same hospital with a fractured skull.
Briggs admitted having punched the child and was later convicted of grievous bodily harm, and sentenced to two years in prison.
The body of the boy's dead twin was then exhumed and a further post-mortem examination was ordered.
That showed he had suffered extensive fractures to his ribs and body, none of which have ever been explained.