Officials said Laachraoui’s apparent death supports evidence that links an ISIS terror cell believed to have coordinated the attacks on Paris last November and the bloodshed in Brussels at the airport as well as a subway station, killing at least 31 people between the two sites.
In fact, just a day before the Brussels attack, Laachraoui was named by officials who urged the public to help in the search for him.
In addition, sources say, Belgian authorities had some foreknowledge that an attack was being planned in the capital, but it was not specific enough to prevent Tuesday’s terror.
Some information received was useful, and prodded authorities to make raids last week, one of which led to the capture of alleged Paris attacks plotter Salah Abdeslam, a Belgian-born French national captured in Brussels on Friday.
Had he not been caught, Abdeslam would have joined in on the Brussels attacks, sources said.
And there are other ties between Paris and Belgium, NBC News has learned.
Brothers Ibrahim and Khalid El Bakraoui, who each took part and were separately killed in the airport and subway attacks, prosecutors said Wednesday, provided a safe house in Belgium to the terrorists who carried out the carnage in Paris. Some of the bombers met up there before moving on to the French capital. The other brother, meanwhile, helped secure weapons and ammunition for the attackers.
Authorities also said several members of the Paris and Belgium attacks traveled to Syria for training, including to work on their bomb-making skills. To characterize any one of them suspects as a master bomb-maker would be “an exaggeration,” one U.S. official said.
Law enforcement had been in pursuit of Laachraoui — Moroccan-born and Brussels-raised — as a suspected accomplice to Abdeslam.
Abdeslam spent four months on-the-run as authorities across Europe tried to root him out, finally cornering him in the Brussels neighborhood of Molenbeek. Authorities say he was working with Laachraoui, who had been under the alias of Soufiane Kayal andwas traveling with a fake Belgian identity card.
Laachraoui is believed to have constructed the suicide vests used in the Paris siege after his DNA was found on all of them, a French police official told The Associated Press.
He is thought to have traveled to Syria in 2013.
This story originally appeared on NBCNews.com.