Between 2004 and 2012, nearly two-dozen court case documents indicate 350 faulty security clearance records were done for the Office of Personnel Management (OPM), which oversees employment by the federal government. Reuters broke the story Wednesday after reviewing the cases.

The number is only a small portion of the background checks OPM requests from private contractors and special agents annually. 

In 2011, for example, the agency received more than $1 billion to conduct background investigations for more than two million prospective employees, according to the Government Accountability Office. 

One private contract investigator, Reuters reports, pleaded guilty in one case for falsely stating he had interviewed a person. But the person had actually died more than a decade earlier. Another investigator was found guilty of making false statements in checks they did for people who applied for “top secret” clearance jobs, the report says. 

As punishment, Reuters says prosecutors have required defendants to pay more than $1.5 million to the federal government. 

These revelations come as lawmakers and government agencies scrutinize the quality of these investigations. 

After last week’s Navy Yard shooting, law enforcement officials determined the shooter, Aaron Alexis, had a background check done by the same firm that checked out NSA-leaker Edward Snowden. 

Alexis was deemed fit for a secret government security clearance despite violent episodes and arrests in the past. He also was cleared to enlist in the Navy in 2007. 

A bipartisan group of senators introduced legislation over the summer that would hold contractors accountable for background checks down for government employees. 

On Oct. 1, the Senate Homeland Security Committee will hold a hearing on the issue of background checks and government clearances. 

President Obama has also directed the Office of Management and Budget to examine the process.