Brussels attack investigation: Finding those responsible and stopping the next one

The suspect was spotted holding a large bag on surveillance cameras at the station, according to Belgian public broadcaster RTFB. But it's not clear if he was killed in the blast.That brings the total number of suspects to five.They know the names of two bombers, brothers Khalid and Ibrahim El Bakraoui; they know an ISIS bomb-maker, Najim Laachraoui, died at the airport; and they have an image -- albeit a grainy one -- of one suspect who they say is on the run.And they've uncovered what appears to be a hideout, where they found a nail bomb and chemicals.Latest updates on Brussels attacksIn the process of piecing together clues, time is of the essence.It's a race to stop the next attack on European soil -- and it's one they very may well lose, some analysts say."I think Britain is to follow, with more attacks in France," CNN intelligence and security analyst Bob Baer said.