The agent received the list in a readable format from the Missouri State Highway Patrol in January.
Patrol officials told a Missouri Senate committee Thursday the data were never accessed at the federal level because of a technical glitch. But the Social Security Administration's Office of Inspector General said the unreadable version was sent to the agent in 2011.
The investigator was planning to check if anyone who met Missouri's mental health qualifications for a weapons permit had also sought benefits for a mental disability. But the project was dropped.