The collapsed Florida condo was part of a 2015 lawsuit where a resident complained the outer walls weren't being properly maintained

• Champlain Towers in Surfside, Florida, partially collapsed on Thursday, killing at least one.
• At this stage, it's unclear what caused the collapse.
• The condo was the subject of a 2015 maintenance suit. It's unclear if the issues indicated there affected the collapse.
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A resident of the Florida condominium that partially collapsed early Thursday filed a lawsuit in 2015 alleging that one of the building's outer walls was not being maintained properly, court records seen by Insider showed. 

As of Friday morning, rescue workers were still searching for 99 people who remain unaccounted for in the massive collapse of a section of Champlain Towers, at 8777 Collins Avenue in Surfside. One person has been confirmed dead. 

In 2015, Matilde Fainstein filed for damages in the Miami-Dade Circuit Court, saying the building's owners "failed to repair or negligently repaired the common elements and the outside walls of the building." 

The year before, water had started coming in through cracks in the outer wall to Fainstein's terrace, causing damage, the complaint said. The filing said she had previously taken the same issue to court, where the building's owners were found liable. 

The building's owners settled the earlier case, court records showed.

It's unclear what section of the building this related to or whether the issues indicated in the lawsuit had any effect on Thursday's collapse. 

In the aftermath of the collapse, officials are scrambling to understand the cause of the disaster, but officials have not yet released any public records that could offer clues, the Miami Herald reported. 

Numerous factors have been proposed: A 2020 study found that the land the condo was built on showed signs of sinking — though that alone is not likely the cause, the study's author said.

Miami buildings require a full structural inspection 40 years after they're built.

Champlain Towers, which was built 39 years ago, had started to undergo its inspection, but a report had not been submitted to the town clerk, the Herald reported. 

"The bottom line is that's not an old building, and 40-year inspection or not, that kind of thing should not be happening," Mayor Charles Burkett of Surfside told reporters in the wake of the collapse, the Herald reported.