The chief of the Fraud Section in Department of Justice's Criminal Division is reportedly joining former FBI Director Robert Mueller's team to assist with the investigation into Russia's interference in the U.S. election and possible ties to President Donald Trump's campaign.

Sources told Bloomberg that Fraud Section Chief Andrew Weissmann was expected to join the Russian investigation, making him the most senior government official to do so.

According to Bloomberg:

Weissmann’s specialties have included corporate fraud and foreign bribery. For two and half years, he has overseen investigations into Volkswagen AG over diesel-cheating, global banks over market manipulation and Brazil’s state-owned oil company Petrobras over corrupt payments.

Weissmann, who previously worked under Mueller, also took part in the Enron task force during George W. Bush's presidency.

The Justice Department declined to comment.