A former Army Corps of Engineers employee has pleaded guilty to charges of bribery and conspiracy in one of the most brazen corruption schemes in federal contracting, according to court documents.

As part of the plea agreement, Michael Alexander, a former program manager at the Army Corps, has agreed to plead guilty to bribery and conspiracy to launder money from the government, according to records filed Jan. 24.

The three others indicted in the case, Kerry Khan, another former Army Corps program manager, Lee Khan, his son, and Harold Babb, formerly the director of contracts at Eyak Technology, have pleaded not guilty in the case. They were arrested and arraigned Oct. 4.

Two officials with an EyakTek subcontractor—Nova Datacom—have already pleaded guilty, according to the Associated Press.

The indictment alleges bribery, conspiracy and unlawful kickbacks valued at $20 million dollars. The two Army Corps employees allegedly steered a $780 million contract to a government contractor. They are accused of conspiring to hide the money through a series of financial transactions on the Army Corps’ Technology for Infrastructure, Geospatial, and Environmental Requirements (TIGER) contract.

When announcing the indictment in October, U.S. Attorney Ronald C. Machen Jr. described the alleged activity as “one of the most brazen corruption schemes in the history of federal contracting.”