Anne Arundel County Executive John R. Leopold is under investigation by Maryland state prosecutors who are looking into whether he misused government resources by telling his security detail to carry out campaign activities,according to individuals who say they were interviewed in connection with the probe, The Baltimore Sun reports.

Five members of Leopold’s county-funded security detail are negotiating an immunity deal with the Office of the State Prosecutor that would allow them to provide information to investigators without threat of prosecution, according to John M. Singleton, an attorney acting on behalf of the five.

Leopold, a Republican in his second term, said Wednesday that he had “no knowledge” of an investigation but acknowledged that his security detail carried out tasks for him as he was recuperating from back surgery last year. He also criticized his rivals, calling the allegations “political retaliation” and pointing specifically to his recent efforts to alter the county’s binding arbitration agreement, which have angered public safety and other employees.

Read more about the Leopold investiation in The Baltimore Sun.