New details about Brussels attackers' suspicious behavior before attack

BRUSSELS -- As authorities in Brussels continue to search for suspects in last week's deadly Brussels attacks, the superintendent of the apartment the attackers apparently used as a bomb-making factory provided new information about the group's suspicious behavior.

The superintendent was too scared to go on camera, but talked to us in the doorway.

He said that there were five men who came and went regularly from the apartment. They were in a hurry to rent it, paid cash up front, and used a fake identity -- Michael Dos Santos.

• Two Brussels attacks bombers likely still at large
• More arrests in Belgium add to evidence of widespread terror network

He became suspicious that something strange was going on when chemicals leaked through the ceiling into the apartment below. He also said he smelled a noxious odor coming from their rooms.

But the superintendent did not report anything to police, as he said he could not be sure there was something criminal going on. It was only when investigators raided the place after the bombings that a deadly haul of explosives and chemicals were found.

Meanwhile, Belgian police released new airport surveillance tape just before the bombing. They also admitted they are no closer to putting a name to the face of the man known only as "the man in the hat."

Freelance journalist Faycal Cheffou had been picked up by police last Thursday and charged with terrorism and murder. But he had been mistakenly identified as the suspected third airport bomber by the taxi driver who drove the attackers there.

Police released Cheffou Monday due to a lack of evidence against him.

Well-known talk show host Vince Kante used to work with Cheffou at a local radio station. Before Cheffou's release, he told CBS News it was obvious that the man in the video was taller and larger than Cheffou.

"I knew there was a long time I didn't see him, but it was like what the? What the? It's not possible," he said, laughing.

But the constant police bungling is no laughing matter. Despite frequent raids, investigators appear no closer to finding the mysterious man in the hat.