According to various sources close to the investigation, the threat was soon ruled to be without validity, following a sweep of the building.
Several dozen people at the courthouse at the time were forced to evacuate the building as a precaution, as the investigation was conducted.
Polk County Sheriff Johnny Moats says this is the second such threat in as many days at the courthouse, both found to be baseless.
Moats said the threat was likely called in by someone trying to get out of a court date.
The investigation into the source of the threat is still underway.