Federal investigators looking into the Surfside, Florida, condo building collapse that killed 98 people in June 2021 revealed new findings in the probe on Thursday.

The report from the National Institute of Standards and Technology's investigation into the cause of the disaster at the Champlain Towers South building says, "the construction of the pool deck deviated from design requirements" and that the "number of slab reinforcing bars centered over vertical columns was inadequate."

"These deviations weakened the slab-column connections," the report said.

Researchers have been studying subsurface conditions of the site to "determine if sinkholes or excessive settling of the pile foundations might have contributed to the collapse," according to the report.

The preliminary evaluation did not reveal evidence of sinkholes, the new findings show.

Documents released by Surfside town officials in July 2021 revealed that the pool deck of the condo building and the ceiling of the underground parking garage beneath it had needed repairs as early as 1996.

ABC News previously reported that a 2018 Structural Field Survey report released by the city of Surfside found "major structural damage" to concrete structural slabs on the pool deck and failed waterproofing in parts of the tower.

NIST investigators expect their technical work to be completed in late June 2024 and a report with final findings and recommendations is expected by June 2025.