A pool contractor visited the Champlain Towers South condo just 36 hours before half of the building collapsed, killing 10 and leaving over 150 people missing, the Miami Herald reports. Everything about the building looked normal until he found water all over the basement-level garage, he told the paper. The contractor had visited the building to make a bid for a restoration of the pool, part of a renovation that was in the works for the condo. The standing water had concerned him, but he also noticed and photographed severely corroded rebar under the pool and cracked concrete. “I wonder if this was going on in other parts of the building and caused this collapse,” the anonymous contractor told the Herald.

Mohammad Ehsani, an engineer and concrete restoration expert, reviewed the photos the contractor shared with the Herald. He noted the extensive corrosion in the rebar, calling it “very serious” and telling the paper the damage present should have been more of a concern. Maxwell Marcucci, a representative for the building’s association, declined to comment to the Herald.