Investigation continues into the cause of, and culpability for, the November 2015 Fundao tailings dam breach in southeastern Brazil that flooded the Doce River and surrounding areas with 30 million cubic meters of iron mine waste.

Earlier in January, Brazil's Federal Police accused the mine's operator, Samarco—which is jointly owned by BHP Billiton and Vale—of environmental crimes relating to the disaster, which flattened homes in two nearby towns and killed 17 people. On January 21, Samarco announced that its Board had granted CEO Ricardo Vescovi and Operations Director Kleber Terra time off "in order to devote time to working on their defense."

Over 30 million cubic meters of iron mine waste flooded two nearby towns and killed 17 people. Image source: Samarco.All three companies face potential civil damages of almost $5 billion brought against them by the Brazilian government for social and environmental remediation related to the accident.

Samarco representatives dispute allegations by Joaquim Pimenta de Avila, whom it hired to design and oversee construction of the dam, that the company ignored warnings in 2014 of "severe" structural problems that compromised the dam's integrity. De Avila told the Wall Street Journal that he recommended to Samarco that additional structural support should be added at the base of the dam to prevent a potential breach.

Samarco lawyer Mauricio Campos told the newspaper that the company was not warned about the potential for a breach and suggested that a modest earth tremor in the dam's vicinity earlier in the day—of between 2.0 and 2.6 on the Richter scale—might have triggered the event.

Prosecutors are also likely to probe the merits of a report that aired on Brazil's Globo Television Network's Fantastico alleging that Samarco in 2014 and 2015 ignored warnings from sensors located in the dam that detected potential problems based on measurements of ground moisture and stability.

Vale, BHP Billiton and Samarco have jointly engaged New York-based law firm Cleary, Gottlieb, Steen & Hamilton to conduct an external investigation into the cause of the dam breach. BHP Billiton reportedly has committed to publicly release the findings of the investigation.