The sprawling Petrobas corruption scandal continues to grow and stretch across Brazil’s political and economic landscape. Prosecutors handling the case continue to reach new targets and arrest more individuals who profited from the corruption schemes.

For global companies that conducted business with Petrobas, there are real enforcement risks as investigators uncover bribery activity. Recently, it was reported that Brazil prosecutors referred four companies to US law enforcement for investigation related to bribes paid to Petrobas. This number is likely to grow as Brazil investigators uncover more dirt surrounding the Petrobas scandal.

US and Brazil law enforcement have a close working relationship, bolstered by a well-established MLAT process, that has led to several significant joint enforcement actions. The Petrobas scandal presents a unique opportunity for Brazil and the US to coordinate their enforcement investigations.

For right now, Brazil investigators are focused on domestic activity, and for good reason. Just when one year is closed off or completed, another becomes relevant.

It is worth taking a moment to review the history behind the investigation – where Brazil started and how far they have come.

At the heart of the investigation is Paulo Roberto Costa, Petrobas’ head of refining from 2004 to 2012, who was arrested by federal police in a money laundering investigation. In order to escape punishment, Costa confessed to a lot more than money laundering. Instead, he outlined how major construction companies won contracts from Petrobas and diverted 3 percent of the contract value to slush funds for political parties. Investigators were able to identify approximately 10 billion reais ($3.7 billion) in suspicious payments.

Last November, Brazil police arrested 24 executives from Brazil’s six largest construction companies and another former Petrobas executive. Over 100 people have been indicted with crimes arising from the scandal. Most of the alleged bribe takers were affiliated with Brazil’s Workers’ Party, the same party as Brazil’s current President, Dilma Rousseff. Adding to the complications for President Dilma is the fact she headed up Petrobas ans the Chairperson during part of the period of time when Petrobas was collecting bribes. There is no evidence yet of President Dilma’s involvement or even knowledge of the corruption mischief but the investigation is continuing.

Recently, Petrobas President Aldemir Bendine announced that Petrobas was “coming clean and we are being open about mistakes made with company resources.” However, Petrobas’ poor economic performance is creating a real drag on the Brazilian economy. Petrobas has had to write off staggering amounts of money, over $2 billion so far, to corruption and is still a long way from financial recovery.

Last week, Brazilian police arrested Marcelo Odebrecht, the head of Latin America’s largest engineering and construction company Odebrecht SA, and accused his family-run conglomerate of spearheading a bribery scheme at Petrobas. Police also arrested Otavio Marques Azevedo, CEO of Andrade Gutierrez, Brazil’s second-largest builder.

Odebrecht, Azevedo and other top executives were arrested in Sao Paulo and were flown to the southern city of Curitiba, the city where federal investigators are conducting the Petrobas investigation.

The arrest of Odebrecht, who has personal ties to former Brazil President Luiz Inacio Lula de Silva, brings the scandal closer to the political heart of the ruling Worker’s Party. Last month federal prosecutors opened a separate investigation into whether former President Lula improperly used his connections to benefit Odebrecht, saying he had frequently traveled abroad at Odebrecht’s expense since 2011.

For global companies that conducted business with Petrobas, there are real enforcement risks as investigators uncover bribery activity. Recently, it was reported that Brazil prosecutors referred four companies to US law enforcement for investigation related to bribes paid to Petrobas. This number is likely to grow as Brazil investigators uncover more dirt surrounding the Petrobas scandal.