NCA bomber Domenic Perre has collapsed moments after being found guilty of the 1994 crime.
An ambulance was sent to the Sir Samuel Way building, which houses the Supreme Court, shortly before 10am.
Minutes earlier, Justice Kevin Nicholson had found Perre guilty of the murder of Detective Sergeant Geoffrey Bowen and the attempted murder of lawyer Peter Wallis.
A Department of Correctional Services spokesperson confirmed "the prisoner experienced a medical episode and is receiving appropriate medical treatment".
SA Ambulance Service confirmed a man in his 60s was taken to the Royal Adelaide Hospital.
The court had heard earlier this year that Perre had been unwell.
In March 1994, Perre sent a parcel bomb to Detective Sergeant Bowen's Waymouth Street office in revenge over the police officer's investigation into the Perre family's drug business.
Detective Sergeant Bowen was killed in the bombing and Mr Wallis received burns to 35 per cent of his body and lost an eye.
Perre was immediately identified as a suspect, but the first set of charges were dropped in September 1994.
He was charged again in 2018.
After a seven-month trial, Justice Kevin Nicholson found Perre guilty of murder and attempted murder.
Perre has been in custody since 2017 over unrelated drug and firearm charges.
He is expected to be sentenced for the murder and attempted murder in September.
In March, Perre was also found guilty of aggravated assault after he spat on a detective at the Adelaide Remand Centre in November 2018.
Community relieved by guilty verdict
Outside of court, police and family members of the two victims expressed relief at the verdict.
Police Commissioner Grant Stevens praised investigators for never giving up on the case.
"What can I say after 28 years … we have an outcome today which vindicates the unrelenting effort of the South Australia police, the ICAC and other investigators across Australia," he said.
"This is, I think, the result we were obviously hoping for and it is a testament to the investigating over years of so many people who have been involved."
Major Crime Superintendent Detective Des Bray said South Australia was a much safer place with Perre behind bars.
"Today's decision is a demonstration of the persistence and the determination of an awesome investigation team — police, forensic people, the DPP, law enforcement teams across Australia and internationally.
"Without all of those people combined, we would not have had the result that we've had."
Mr Wallis's daughter, Genievieve, expressed sadness that her father had passed away before justice was served.
Sergeant Bowen's brother-in-law, David Gorton, said the bombing had "always been on the forefront of the our thoughts".
