Workers said the Chinese developer used substandard materials during construction as it tried to cut costs. Investigators also said they found substandard steel bars in the rubble.
Only one building in Bangkok collapsed in Friday's earthquake that rocked Myanmar, hundreds of miles away. Reconstruction efforts continue, with at least 15 people killed and dozens still missing. Determining the cause could take months.
However, interviews with workers who visited the site, as well as early official findings, have revealed potential problems with the design and quality of construction.
At the center of attention is China Railway 10th Engineering Group, a Chinese state-owned company running about a dozen other projects in Thailand, whose contractors tried to remove documents from the crash site.
Behind the Chinese company is its parent company, China Railway Group, a Chinese infrastructure giant with mounting debt, a thirst for new projects and subsidiaries facing allegations of poor safety in several countries.
Workers in Bangkok told The New York Times that China Railway Company 10, part of the consortium building the building, underpaid contractors who used lower-quality materials and narrower-than-usual columns.
Thai officials analyzing twisted metal from the ruins said they found substandard steel bars made at a Chinese-owned Thai factory that authorities closed in December.
