Barrera’s case, which ended last month with a prison sentence of at least three years, is part of what Justice Department lawyers describe as a recurring pattern of corruption that spans a broad cross section of the military.

In a period when the nation has spent freely to support wars on multiple fronts, prosecutors have found plentiful targets: defendants who bill for services they do not provide, those who steer lucrative contracts to select business partners and those who use bribes to game a vast military enterprise.

Despite numerous cases that have produced long prison sentences, the problems have continued with a frequency that law enforcement officials consider troubling.

“The schemes we see really run the gamut from relatively small bribes paid to somebody in Afghanistan to hundreds of millions of dollars’ worth of contracts being steered in the direction of a favored company who’s paying bribes,” Assistant Attorney General Leslie Caldwell, head of the Justice Department’s criminal division, said.

In the past few months alone, four retired and one active-duty Army National Guard officials were charged in a complex bribery and kickback scheme involving the awarding of contracts for marketing and promotional materials. A trucking company driver pleaded guilty to bribing military base employees in Georgia to obtain freight shipments — often weapons which required satellite tracking — to transport to the West Coast.

More recently, a former contractor for the Navy’s Military Sealift Command, which provides transportation for the service, was sentenced to prison along with a businessman in a bribery scheme in which cash, a wine refrigerator and other gifts traded hands in exchange for favorable treatment on telecommunications work. Also, three men, including two retired Marine Corps senior officers, were charged with cheating on a bid proposal for maintenance work involving Marine One helicopters that service the White House.

Justice Department lawyers say they don’t consider the military more vulnerable to corruption than any other large organization, but that the same elements that can set the stage for malfeasance — including relatively low-paid workers administering lucrative contracts, and heavy reliance on contractor-provided services — also exist in the military.

The Commission on Wartime Contracting in Iraq and Afghanistan estimated that between $31 billion and $60 billion was lost to waste and fraud during U.S. operations in those countries. The Justice Department says it brought 237 criminal cases from November 2005 to September 2014 arising from war-zone misconduct — often contracting and procurement fraud.

“We just were not equipped to do sufficient oversight and monitoring on the front end, and we didn’t have sufficient accountability mechanisms on the back end, which led to enormous problems,” said Laura Dickinson, a national security law professor at George Washington University.