Former CBS Employees Federal Credit Union CEO Edward Rostohar said he was able to steal and conceal his $40 million embezzlement for 20 years because NCUA auditors “didn’t really know what to look for” during examinations, according to court documents filed in U.S. District Court in Los Angeles.

In addition to Rostohar’s insider knowledge as a former NCUA auditor, he also identified and exploited a weakness in the credit union’s data processing system.