Around 1:30 a.m. on June 24, 2021, 98 people were killed when Champlain Towers South, a 40-year-old condominium in Surfside, Florida, collapsed. Raysa Rodriguez was on the ninth floor of a part of the building that somehow remained standing.
"I am sound asleep, and I hear this awful noise and I didn't know what it was. It felt like a mountain coming down. And, two seconds later, all I remember is literally being thrown out of my bed and landing in front of the bed," Rodriguez told Sharyn Alfonsi for this week's 60 Minutes. "And there was a small balcony. So I stepped out and my brain just couldn't compute what I was looking at. I said to myself, 'where's the building?' You know, screaming at this time, "where's the building?"
The elevators were gone. The stairwells clogged with concrete.
"There's no way for me to get out and I think I just snapped into, 'Okay, this is the situation. I'm terrified. I don't want to die tonight,'" Rodriguez said.
Rodriquez started navigating a way down, helping an elderly neighbor through dark hallways, and over the debris in stairwells.
It took more than two hours before they reached a floor low enough to be rescued from with a ladder.
More than a year later, all that's left of the building is a concrete scar in the ground. The names of the victims are listed on a fence that surrounds the site. It includes retirees and young families.
And investigators still don't know why the building fell.
The answer could be in a massive Miami warehouse where 800 tons of remnants from the Champlain Towers is being stored.
The facility is off limits to anyone except federal investigators. They are now combing through the twisted steel and concrete for clues.
Glenn Bell is one of the team's lead investigators. He spoke to 60 Minutes from the headquarters of the National Institute of Standards and Technology, the agency conducting the federal investigation.
"Our timeline for this investigation was to finish our technical findings by the fall of 2023," Bell told Alfonsi. "Then we have to work on our report and recommendations. And we're looking for that the fall of 2024."
"A lot of people in Florida can't understand why this is taking as long as it is," Alfonsi said.
"I want them to know that we're working as fast as we can," Bell said. "And the implications for our findings are huge. We have to get this right."
Based on what's found, Bell's team will recommend any necessary changes to building codes or construction methods nationwide.
"We have over 600 pieces of the structure that we're going to be doing a lot of testing on," Bell said. "And the more that you put together, the more the pieces of the puzzle begin to emerge, and stories emerge."
But so far, Bell and his team haven't found any clear answers.
"Right now, we're pursuing about two dozen hypotheses about what the causes may have been," Bell said.
Among the possibilities are shoddy construction, bad design, or faulty materials. Glenn Bell was on the engineering team that investigated the collapse of the World Trade Center following the 9/11 attack and came out of retirement to try and solve the Surfside mystery.
"I've been investigating failures for over 40 years. And this particular investigation I can say is one of the most complex and challenging that has ever been undertaken," Bell said. "Sometimes in building failures, the immediate causes are relatively apparent. We have-- no such apparent cause-- in Champlain Towers after well more than a year."
Investigators started scanning pieces of the debris into a massive 3D database last spring. Preliminary lab tests on building materials began in August. Bell said if investigators discover anything that poses a danger to other buildings, they will reveal it immediately.
"Is it possible after the investigation's complete that you won't know what caused the building to collapse?" Alfonsi asked.
"I'm confident that we will," Bell said. "But it will take a long time."
Back in Surfside, Allyn Kilshiemer said the investigation doesn't need to take two more years. He was hired by the City of Surfside hours after the collapse to conduct its own investigation.
"We have to get to the trigger. I always say a building talks to you if you know how to listen to it alright," Kilshiemer said. "And it finds a way to support itself or it finally says, 'I give up. I can't support it. I'll fall down.'"
Kilsheimer, a renowned engineer, was part of the investigation teams after the Oklahoma City federal building bombing and the 9/11 attack on the Pentagon. But in Surfside Kilsheimer said he's about eight months behind where he wanted to be. That's because he is still negotiating with the federal investigators for permission to do his own tests on the building samples locked up in that warehouse.
"I've never run into it before," Kilsheimer told Alfonsi.
"Not with the Pentagon? Not with the Oklahoma City bombing?" Alfonsi asked.
"I've never run into it before," Kilsheimer said. "It's very unusual."
It took until this past August before Kilsheimer was allowed to do his first big on-site test.
for more features.