Authorities uncovered bomb material and a farewell message from a suspected suicide bomber Wednesday as details emerged of the Brussels attackers: two brothers who brought chaos and carnage to the city at the heart of European unity.
One person was taken into custody, then released, as authorities tried to chase down possible leads for a key suspect on the run.
But the brothers - Khalid and Ibrahim el-Bakraoui, both Belgians with criminal records - were identified by authorities as suicide bombers who attacked the Brussels metro and airport on Tuesday, claiming at least 31 lives and injuring 270 people. The Islamic State claimed responsibility.
The pair also opened links to last year's Paris massacres. Authorities believe both had connections to Salah Abdeslam, who helped carry out the bloody siege in November and was apprehended last week by Belgian authorities.
The probes increasingly suggest a web that draws together the Paris plot - hatched mostly in Brussels - and Tuesday's blasts that struck in the shadows of offices directing the Western alliance NATO and the European Union.
As part of the manhunt and investigations, security officials found a will in a trash can at the apartment of Ibrahim el-Bakraoui, 29, the elder brother. It revealed how he was desperate to blow himself up because he did not want to go to prison like his friend, Paris bomber Salah Abdeslam.
The typed note, found next to 15kg of homemade explosives, an AK-47 and an ISIS flag, said: "I don't know what to do. I'm in a hurry. I'm on the run. People are looking for me everywhere. And if I give myself up then I'll end up in a cell... I would rather die than end up in a cell."
He is suspected of perpetrating a suicide attack at the airport. The younger brother was identified by his fingerprints in the metro attack, prosecutor Frederic Van Leeuw said.