Evidence is emerging that the Islamic State militants may have launched their attack on Brussels in haste because they feared authorities were closing in on them.
Police also say that same Islamic State cell carried out the attacks on both Paris and Brussels.
On a day of mourning across Belgium following Tuesday's bombings of the Brussels airport and subway that killed 31 people and wounded more than 270, more information about the four attackers was found.
European security officials said one of the suicide bombers was Najim Laachraoui, a Moroccan-born Belgian whom police have hunted as the suspected bombmaker in the November 13 attacks on Paris by the Islamic State that killed 130 people.
The other two suicide bombers were Belgian-born brothers, Ibrahim El Bakraoui, and his younger brother, Khalid, both known to the police as common criminals, not anti-Western radicals.
Details of the investigation from chief prosecutor Frederic Van Leeuw pointed to a rising sense of panic among the three bombers who blew themselves up.
An unidentified fourth man who was shown in airport video surveillance footage remains at large after Van Leeuw said his suitcase bomb failed to detonate properly.
Authorities say he was the man in a light jacket and hat on the far right of the video footage.
Van Leeuw said the bomb did partially explode after police had already evacuated the terminal, injuring nobody.
The prosecutor said a laptop seized from a garbage can on a street outside the brothers' last known address contained a message purportedly from Ibrahim El Bakraoui that indicated he was expecting to be arrested imminently following Friday's capture in Brussels of the suspected ringleader of the Paris attacks, Salah Abdeslam.
"I don't know what to do, I'm in a hurry, people are looking for me everywhere," Van Leeuw quoted the message as saying. "If I give myself up I'll end up in a cell next to him," - an apparent reference to the just-arrested Abdeslam.
Police were drawn to the brothers' apartment Tuesday night thanks to a tip from a taxi driver who had unwittingly delivered them to the airport, Van Leeuw said.
Inside the northeast Brussels residence they found an apparent bomb-making factory, including 15 kilograms of homemade explosives and nails for use as shrapnel.
At the core of the Belgian investigation is a photo taken from the airport's surveillance cameras showing three attackers walking side by side as they push luggage carts.
Van Leeuw said the middle figure has been identified as Ibrahim El Bakraoui, while the two men flanking him remained unidentified.
But two security officials told the AP that Laachraoui's DNA was verified as that of one of Tuesday's suicide bombers after samples were taken from remains found at the airport.
Since prosecutors said Khalid El Bakraoui was killed in the subway bombing, that would make Laachraoui the remaining unidentified figure on the far left of the airport video footage.
Belgian authorities have been looking for Laachraoui since last week, suspecting him of being an accomplice to Abdeslam, who was arrested Friday in the Brussels neighbourhood where he grew up.
Laachraoui is believed to have made the suicide vests used in Paris, a French police official told the AP, adding that Laachraoui's DNA was found on all of the vests as well as in a Brussels apartment where they were made.
The official spoke on condition of anonymity because he wasn't authorised to discuss an ongoing investigation. Seven of the Paris attackers blew themselves up or were slain by police.
French and Belgian authorities have said the network behind the Paris attacks was much larger than initially thought - and developments this week suggest the same group could have staged the violence both in Paris and Brussels.
"It's the same team," said a French senator, Nathalie Goulet, who is co-leader of a parliamentary commission on studying jihadi networks.
She said Abdeslam should have had little difficulty organising more recruits following his November escape from France.
"He probably had 10 more at hand who would be ready to do the same thing tomorrow morning," she said, describing his Brussels acolytes as "like a scout troop ... a troop of death."
A Belgian official working on the investigation told AP it is a "plausible hypothesis" that Abdeslam was helping to organise the Brussels attack. The official spoke on condition of anonymity because he was not authorised to discuss the investigation.