Here is an article from 2008, Center for Public Integrity which discusses whether government agencies with responsibility for oversight have been able to do their jobs. I will note that from what I have been hearing things are not improving much. There appears to have been a near decade-long failure of disconnected criminal investigation cases, case files languishing on people's desks that were not allowed to progress, and bad actors trying to impede oversight agencies employees, particularly field employees from doing their jobs. If we recruited people for a whistleblower union, the list would be long.
If the taxpayers ever learn of just how much fraud waste and abuse they have been subjected to and have had to pay for because of not only corruption in defense contractors, but also within the ranks of government agency management (appointees and career SES/GS), there would be no end of righteous indignation and calls for prosecutions. GFS
Link to original: http://www.publicintegrity.org/blog/entry/909/