DES MOINES, Iowa (AP) — An Iowa agency is keeping secret a list of about two dozen former criminal offenders who were improperly granted credentials to work for private security firms.

The Iowa Department of Public Safety denied an open records request Friday that sought the identities of those individuals whose security cards were recently revoked.

The revocations came after the discovery that the department granted 5,800 private security employees credentials to work in Iowa without undergoing mandatory federal criminal background checks. The department has for a year worked to retroactively complete those checks. Commissioner Stephan Bayens said it has revoked 20 to 25 cards of those found to have disqualifying criminal histories.

In keeping the list secret, department lawyer Catherine Lucas cited a state law that says names of employees of licensed security firms “shall be held as confidential.”

But it’s unclear whether that law applies to those revoked. Other parts of the law allow the department to release information about disciplinary action taken against licensees and to confirm whether an individual is an employee of a licensed agency.