The unusual arrangement helped Clinton retain personal control over the system that she used for her public and private duties and that has emerged as an issue for her campaign. But, according to the campaign official, it also ensured that taxpayer dollars were not spent on a private server that was shared by Clinton, her husband and their daughter as well as aides to the former president.

That State Department staffer, Bryan Pagliano, told a congressional committee this week that he would invoke his Fifth Amendment rights against self-incrimination instead of testifying about the setup.

The private employment of Pagliano provides a new example of the ways that Clinton — who occupied a unique role as a Cabinet secretary who was also a former and potentially future presidential candidate — hired staff to work simultaneously for her in public and private capacities…

Pagliano did not list the outside income in the required personal financial disclosures he filed each year. The State Department has said Pagliano concluded his full-time service in February 2013, which coincides with Clinton’s departure as secretary. He remains a State Department contractor doing work on “mobile and remote computing functions,” according to a State Department spokesman.