Federal investigators and prosecutors fudged data on the number of anti-terrorism investigations and cases for the four years after 9/11, according to an audit by US Department of Justice Inspector General Glenn A. Fine released Tuesday.

In a report on terrorism-related incidents and case-loads, the inspector general found that "some of these statistics were significantly overstated or understated." According to the audit, DOJ officials used non-terror-related immigration violations and drug trafficking to inflate the number of anti-terror cases reported.

The data was collected from multiple DOJ divisions, including the FBI, the Executive Office of US Attorneys, the Criminal Division, and the US Attorney's Office , and is used to monitor the DOJ's efficiency in fighting terrorism.