The Transportation Security Administration investigated and closed 9,622 cases of employee misconduct between the years 2010 and 2012, according to a report released Tuesday by the Government Accountability Office.
The figure marked a 26 percent increase in misconduct cases in a three-year period.
Thirty-two percent of the cases involved problems with workers showing up for their jobs, according to the report, and 20 percent had to do with security and screening.
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In one case mentioned in the GAO report, an employee left an assigned checkpoint to help a family member get a bag—later found to contain "numerous prohibited items"—past screening. The employee was suspended for seven days, according to the report.
In another case from January 2012, two former employees of the TSA were sentenced to six months in jail after they admitted to having stolen $40,000 from a bag at John F. Kennedy Airport, NBC New York reported.
The report was released ahead of a hearing before the House Homeland Security Committee on Wednesday morning that was scheduled to include representatives from the TSA and GAO.
Of the more than 9,000 misconduct cases closed by the TSA over the three-year period, nearly half resulted in a letter of reprimand, while employees were suspended in 31 percent of cases, according to the report. Only 17 percent of the employees found to have engaged in misconduct were removed from their jobs.
The agency is nearly 12 years old, and has 55,000 employees and a budget of more than $7.5 billion.
Lawmakers had harsh words for the TSA ahead of Wednesday's hearing.
Rep. Jeff Duncan, R-S.C., the chairman of the subcommittee on oversight and management efficiency, said in a statement that he looked forward to "hearing from TSA on its plans to regain the confidence of the American people."
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"The report's findings show that TSA plays fast and loose with its use of recommended penalties for misconduct. When it comes to sleeping on duty, TSA is more likely to give a slap on the wrist through a reprimand letter than the standard penalty of suspensions or termination," Duncan said in the prepared statement.
"TSA has already been publicly scrutinized for its behavior and treatment of the American public, and when Americans hear about ethical misconduct from TSA employees, whether it be theft, neglect of duty, or even abusive language, it makes the problem even worse."