In the latest development in a federal probe of alleged contracting fraud, a former Army Corps of Engineers manager and his son have pleaded guilty to bribery and conspiracy charges connected to Corps contracts.

Kerry F. Khan, 54, a former program manager in the Corps Directorate of Contingency Operations, entered a guilty plea on May 17 in U.S. District Court for the District of Columbia to charges of bribery and conspiracy to commit money laundering.

Ronald C. Machen, Jr., U.S. Attorney for the District of Columbia, called Khan “the ringleader of the largest bribery and bid-steering scheme in the history of federal contracting.”

Federal officials said Kerry Khan and others attempted to obtain more than $30 million mainly by submitting inflated invoices, which the alleged conspirators called “overhead,” which Khan, several contractors and others involved agreed to divide, according to his written statement of offense filed in the court.

Also pleading guilty to a money-laundering conspiracy charge was Kerry Khan’s son, 31-year-old Lee Khan, who did not work for the Corps.

Counting the Khans, eight men have pleaded guilty since last September to corruption charges in the case. Among them are: Michael A. Alexander, who also had been a Corps program manager; Harold F. Babb, former director of contracts with Eyak Technology LLC, an Alaska Native-owned small business; and James Edward Miller, owner of Big Surf Construction Management LLC.

Machen said that "the investigation in the case is continuing and that more developments are expected," according to Bill Miller, a spokesman for the U.S. Attorney.

Kerry Khan worked for the Corps Directorate of Contingency Operations from 1994 until he was arrested in October 2011.